水利专业混凝土重力坝毕业论文中英文资料外文翻译文献
水利水电工程毕业设计英文翻译,混凝土重力坝
Concrete Gravity DamThe type of dam selected for a site depends principally on topographic, geologic,hydrologic, and climatic conditions. Where more than one type can be built, alternative economic estimates are prepared and selection is based on economica considerations.Safety and performance are primary requirements, but construction time and materials often affect economic comparisons.Dam ClassificationDams are classified according to construction materials such as concrete or earth. Concrete dams are further classified as gravity, arch, buttress, or a combination of these. Earthfill dams are gravity dams built of either earth or rock materials, with particular provisions for spillways and seepage control.A concrete gravity dam depends on its own weight for structural stability. The dam may be straight or slightly curved, with the water load transmitted through the dam to the foundation material. Ordinarily, gravity dams have a base width of 0.7 to 0.9 the height of the dam. Solid rock provides the best foundation condition. However, many small concrete dams are built on previous or soft foundations and perform satisfactorily. A concrete gravity dam is well suited for use with an overflow spillway crest. Because of this advantage, it is often combined with an earthfill dam in wide flood plain sites.Arch dams are well suited to narrow V- or U-shaped canyons. Canyon walls must be of rock suitable for carrying the transmitted water load to the sides of the canyon by arch action. Arch sections carry the greatest part of the load; vertical elements carry sufficient load through cantilever action to produce cantilever deflections equal to arch deflections. Ordinarily, the crest length-to-height ratio should be less than 5, although greater ratios have been used. Generally, the base width of modern arch dams is 0.1 to 0.3 the height of the impounded water. A spillway may be designed into the crest of an arch dam.Multiple arches similarly transmit loads to the abutment or ends of the arch. This type of dam is suited to wider valleys. The main thrust and radial shears are transmitted to massive buttresses and then into the foundation material.Buttress dams include flat-slab, multiple-arch, roundhead-buttress, and multiple-dome types. The buttress dam adapts to all site locations. Downstream face slabs and aprons are used for overflow spillways similar to gravity dam spillways. Inclined sliding gates or light-weight low-head gates control the flow.The water loads are transmitted to the foundation by two systems of load-carrying members. The flat slabs, arches, or domes support the direct water load. The face slabs are supported by vertical buttresses. In most flat-slab buttress dams, steel reinforcement is used to carry thetension forces developed in the face slabs and buttress supports. Massive-head buttresses eliminate most tension forces and steel is not necessary.Combiantion designs may utilize one or more of the previously mentioned types of dams. For example, studies may indicate that an earthfill dam with a center concrete gravity overflow spillway section is the most economial in a wide, flat valley. Other design conditions may dictate a multiple-arch and buttress dam section or a buttress and gravity dam combination.Site ExplorationThe dam location is determined by the project’s functions. The exact site within the general location must be determined by careful project consideration and systematic studies.In preliminary studies, two primary factors must be determined-the topography at the site and characteristics of the foundation materials. The first choice of the type of dam is based primarily on these two factors. However, the final choice will usually be controlled by construction cost if other site factors are also considered.Asite exploration requires the preparation of an accurate topographic map for each possible site in the general location. The scale of the maps should be large enough for layout. Exploration primarily determines the conditions that make sites usable or unusable.From the site explorations, tentative sketches can be made of the dam location and project features such as power plants. Physical features at the site must be ascertained in order to make a sketch of the dam and determine the position of materials and work plant during construction. Other factors that may affect dam selection are roadways,fishways, locks, and log passages.TopographyTopography often determines the type of dam. For example, a narrow V-shaped channel may dictate an arch dam. The topography indicates surface characteristics of the valley and the relation of the contours to the various requirements of the structure. Soundness of the rock surface must be included in the topographic study.In a location study, one should select the best position for the dam. An accurate sketch of the dam and how it fits into the topographic features of the valley are often sufficient to permit initial cost estimates. The tentative location of the other dam features should be included in this sketch since items such as spillways can influence the type and location of the dam.Topographic maps can be made from aerial surveys and subsequent contour plotting or they can be obtained from governmental agencies. The topographic survey should be correlated with the site exploration to ensure accuracy. Topographic maps give only the surface profile at thesite. Further geological and foundation analyses are necessary for a final determination of dam feasibility.Foundation and Geological InvestigationFoundation and geological conditions determine the factors that support the weight of the dam. The foundation materials limit the type of dam to a great extent, although such limitations can be compensated for in design.Initial exploration may consist of a few core holes drilled along the tentatively selected site location. Their analysis in relation to the general geology of the area often rules out certain sites as unfeasible, particularly as dam height increases. Once the number of possible site locations has been narrowed down, more detailed geological investiagtions should be considered.The location of all faults, contacts, zones of permeability, fissures, and other underground conditions must be accurately defined. The probable required excavation depth at all points should be derived from the core drill analysis. Extensive drilling into rock formations isn’t necessary for small dams. However, as dam height and safety requirements increase, investigations should be increased in depth and number. If foundation materials are soft, extensive investigations should determine their depth,permeability, and bearing capacity. It is not always necessary orpossible to put a concrete dam on solid rock.The different foundations commonly encountered for dam construction are: (1)solid rock foundations, (2) gravel foundations, (3) silt or fine sand foundations, (4) clay foundations, and (5) nonuniform foundation materials. Small dams on soft foundation ( item 2 through item 5 ) present some additonal design problems such as settlement, prevention of piping, excessive percolation, and protection of foundation from downstream toe erosion. These conditions are above the normal design forces of a concrete dam on a rock foundation. The same problems also exist for earth dams.Geological formations can often be pictured in cross-section by a qualified geologist if he has certain core drill holes upon which to base his overall concept of the geology. However, the plans and specifications should not contain this overall geological concept. Only the logs of the core drill holes should be included for the contractor’s estimates. However, the geological picture of the underlying formations is a great aid in evaluating the dam safety. The appendix consists of excerpts from a geologic report for the site used in the design examples.HydrologyHydrology studies are necessary to estimate diversion requirements during construction, to establish frequency of use of emergency spillways in conjunction with outlets or spillways, to determine peak dischargeestimates for diversion dams, and to provide the basis for power generation. Hydrologic studies are complex; however, simplified procedures may be used for small dams if certain conservative estimates are made to ensure structural safety.Formulas are only a guide to preliminary plans and design computations. The empirical equations provide only peak discharge estimates. However, the designer is more interested in the runoff volume associated with discharge and the time distribution of the flow. With these data, the designer knows both the peak discharge and the total inflow into the reservoir area. This provides a basis for making reliable diversion estimates for irrigation projects, water supply, or power generation.A reliable study of hydrology enables the designer to select the proper spillway capacity to ensure safety. The importance of a safe spillway cannot be overemphasized. Insufficient spillways have caused failures of dams. Adequate spillway capacity is of paramount importance for earthfill and rockfill dams. Concrete dams may be able to withstand moderate overtopping.Spillways release excess water that cannot be retained in the storage space of the reservoir. In the preliminary site exploration, the designer must consider spillway size and location. Site conditions greatly influence the selection of location, type, and components of a spillway. The design flows that the spillway must carry without endangering the dam areequally important. Therefore, study of streamflow is just as critical as the foundation and geological studies of the site.附录2外文翻译混凝土重力坝一个坝址的坝型选择，主要取决于地形、地质、水文和气候条件。
水利工程三峡水利枢纽工程外文翻译文献
水利工程三峡水利枢纽工程外文翻译文献(文档含中英文对照即英文原文和中文翻译)The Three Gorges ProjectsFirst. The dam site and basic pivot disposalThe Three Gorges Projects is select to be fixed on San Dou Ping in Yichang, located in about 40 kilometers of the upper reaches of key water control project of Ge Zhou Ba which was built. River valley, district of dam site, is widen, slope, the two sidesof the bank is relatively gentlely. In the central plains have one island (island, fort of China,), possess the good phased construction water conservancy diversion condition. The foundation of pivot building is the hard and intact body of granite. Have built Yichang and gone to stride bridge that place of 4 kilometers in the about 28 -km-long special-purpose expressway of building site and dam low reaches --West Yangtze Bridge of imperial tomb. Have also built the quay of district of a batch of dams. The dam district possesses the good traffic condition.Two. Important water conservancy project buildings1. damThe dam is a concrete gravity dam, which is 2309 meters long, it’s height is 185meters , the dam is 181 meters high the most. Release floodwater dam section lie riverbed, 483 of the total length, consist of 22 form hole and 23 release floodwater in the deep hole, among them deep hole is imported 90 meters , the mouth size of hole is 7*9 meters; Form hole mouth is 8 meter wide, overflow weir is 158 meters, form hole and deep hole adopt nose bank choose, flow way go on and can disappear. Dam section lies in and releases floodwater on a section of both sides of the dam in the hydropower station, there are hydropower stations that enter water mouth. Enter water mouth baseplate height 108 meters. Pressure input water pipeline for carry person who in charge of, interior diameter 12.40, adopt the armored concrete to receive the strength structure. Make and let out flow of 102500 cubic meters per second the most largely in the dam site while checking the flood.2. power stationsThe power stations adopt the type after the dam to assign the scheme, consist of two groups of factory buildings on left, right and underground factory building altogether. Install 32 sets of hydroelectric generating set together, 14 factory buildings of left bank among them, 12 factory buildings of right bank, 6 underground factory buildings. The hydraulic turbine, in order to mix the flowing type, the specified capacity of the unit of the unit is 700,000 kilowatts.3. open up to navigation buildingThe open up to navigation buildings include permanent lock and ship lift (of the the technological public relations, the steel cable that plans to be replaced with spiral pole technology in the original plan promotes technology), lie in the left bank. Permanent lock double-line five continuous chain of locks. Single grades of floodgate room effective size for 280*34*5, can pass the 10,000 ton-class fleet. The promoting type for single track first grade vertically of the ship lift is designed, it is 120*18*3.5 meters to bear the effective size of design of railway carriage or compartment of ship, can pass a combination vessel of 3000 tons once. Total weight is 11800 tons to bear the design of railway carriage or compartment of ship when operating, it is 6000 newtons to always promote strength.Three.The major project amount and arranges in time limit The subject building of the project and major project amount of the waterconservancy diversion project are: Excavate 102,830,000 cubic meters in cubic metre of earth and stone, fill out and build 31,980,000 cubic meters in cubic metre of earth and stone, concrete builds 27,940,000 cubic meters, 463,000 tons of reinforcing bars, make and fit 32 with hydroelectric generating set. All project construction tasks were divided into three stages and finished, all time limit was 17 years. The first stage (1993-1997 year) is preparation of construction and the first stage of the project, it takes 5 years to construct, regard realizing damming in the great river as the sign. The second stage (1998-2003 year) is the second stage, it takes 6 years to construct, lock as initial conservation storage of the reservoir, the first batch of aircrews generate electricity and is open up to navigation with the permanent lock as. The third stage (2004-2009 year) is the third stage of the project, it takes 6 years to construct, regard realizing the sign all aircrews generate electricity and finish building with all of multi-purpose project as. One, two project finish as scheduled already, the third stage of the project in inside the plan to construct too, ship lift tackle key problems of not going on intensely.Four. Enormous benefit of the Three Gorges Projects The Three Gorges Projects is the greatest water control project in China ,also in the world , it is the key project in controlling and developing the Changjiang River. The normal water storage level of the Three Gorges Projects reservoir is 175 meters, installed capacity is 39,300 million cubic meters; The total length of the reservoir is more than 600 kilometers, width is 1.1 kilometers on average; The area of the reservoir is 1084 sq. km.. It has enormous comprehensive benefits such as preventing flood, generating electricity, shipping,etc..1. prevent floodPrimary goal of building the Three Gorges Projects is to prevent flood . The key water control project in Sanxia is the key project that the midstream and downstream of the Changjiang River prevent flood in the system. Regulated and stored by the reservoir of Sanxia, form the capacity of reservoir in the upper reaches as river type reservoir of 39,300 million cubic meters, can regulate storage capacity and reach 22,150 million cubic meters, can intercept the flood came above of Yichang effectively, cut down flood crest flow greatly, make Jingjiang section prevent floodstandard meet, improve from at present a about over ten years to once-in-a-hundred-year. Meet millennium first special great flood that meet, can cooperate with Jingjiang flood diversion partition application of flood storage project, the crushing calamity of preventing the occurrence of both sides of section of Jingjiang and bursting in the main dike, lighten midstream and downstream losing and flood threat to Wuhan of big flood, and can create conditions for administration of Dongting Hu district.2. generates electricityThe most direct economic benefits of the Three Gorges Projects is to generate electricity . Equilibrate the contradiction that contemporary China develops economic and serious energy shortage at a high speed, the hydroelectric resources that a clean one can be regenerated are undoubtedly optimum choices. The total installed capacity of power station of Sanxia is 18,200,000 kilowatts, annual average generation is 84,680 million kilowatt hours. It will offer the reliable, cheap, clean regenerated energy for areas such as East China, Central China and South China of economic development, energy deficiency,etc.It play a great role in economic development and environmental pollution of reducing.Electric power resource that the Three Gorges Projects offers, if given a workforce of electricity generation by thermal power, mean building 10 more thermal power plants of 1,800,000 kilowatts, excavate more 50 million tons of raw coals every year on average. Besides environment of influencing of the waste residue, it will also discharge a large number of carbon dioxide which form the global greenhouse effects every year, cause the sulfur dioxide of acid rain, poisonous gas carbon monoxide and nitrogen oxide. At the same time, it will also produce a large amount of floating dust, dustfall,etc… Thermal power plant and abandon dreg field extensive occupation of land seize more land from East China, Central China area that have a large population and a few land just originally this. This not only makes China bear the pressure that greater environment brings in the future, cause unfavorable influence on the global environment too.3. shippingSanxia reservoir improve Yichang go to Chongqing channel of the ChangjiangRiver of 660 kilometers notably, the 10,000 ton-class fleet can go to the harbour of Chongqing directly. The channel can rise to 50 million tons from about 10 million tons at present through ability in one-way year, transporting the cost can be reduced by 35-37%. Unless until reservoir regulate, Yichang low water flows minimum seasons downstream,whose name is can since at present 3000 cubic meters /second improve until 5000 cubic meters per above second, the shipping condition get greater improvement too to enable the Changjiang River in low water season of midstream and downstream.Five. The questions in building the Three Gorges Projects1. silt issuethe Changjiang River Yichang Duan Nian amount of sand failed 530 million tons, silt the reservoir of Sanxia up. The reservoir blocks water level is 175 meters high, installed capacity is 39,300 million m3 normally,its die water level is 145 meters, the minimum capacity of a reservoir is 17,200 million m3, storage capacity 22,100 million m3, the conservation storage regulates the capacity of reservoir 16,500 million m3. The operation scheme of the reservoir is: Limit height is 145 meters of water level, in flood season, meet flood adjust big under 56700 m3 per second, and power station smooth to let out through deep hole over 3 years, can reduce the sand of the reservoir to deposit. Great flood comes, the reservoir is adjusted bigly, still put and let out 56700 m3per second; Deposit towards the reservoir after the flood. The reservoir begins conservation storage, between about two months and normal water storage level 175 meters high in September. The water level of the storehouse is dropped to 155 meters high before the flood next year, utilize conservation storage to generate electricity. In 155 meters water level, can keep the river shipping of Sichuan. By flood season, the water level was dropped to 145 meters water level again, because the flow was large at that time, could keep the river shipping of Sichuan. This is a reservoir operation scheme of innovation.2. question that the slope comes down by the bank of reservoir areaThe question that the slope comes down is through detailed geological survey by 2 reservoir area banks, there is several to come down potentially on water bank of Kuku of Sanxia, the big one can be up to millions of m3. But closest to dam sitepotential landslide, too far on 26 kilometers, such as happen, come down, shock wave that evoke get dam disappear, reduce 2-3 meters to to be high, it is safe not to influence the dam. In addition, if the slippery wave happens in the bank of the storehouse, because the reservoir is wide and deep, will not influence shipping.3. engineering question of the pivotThe pivot of Three Gorges is 185 meters high concrete gravity dam pivots and 18,200,000kW, the project amount is large, but all regular projects after all, our country has more experience. The stability problem of some foundation can meet the safe requirement through dealing with. 700,000kW hydroelectric generating set, imported from foreign countries in the first batch, was made by oneself at home later. The more complicated one is lock of five grades of Line two, deep-cut in the rock bank, slope reaches 170 meters at the supreme side, the underpart floodgate room vertical 60 meters, high rock slope stability worries about. But the meticulous research of engineer and constructors is designed, blown up and the anchor is firm and excavating, the rock slope is steady in a long-term. There is ship lift of 3000t passenger steamer, it is the biggest in the world, in course of designing and studying, and repair the test and use the ship lift first.4.ecological environment problemThe respect useful to ecological environment of the Three Gorges Projects is: Prevent and cure downstream land and cities and towns to flood, reduce the air pollution of electricity generation by thermal power, improve some climate, the reservoir can breed fish etc.. The respect disadvantageous to ecology is: Flood more than 300,000 mu of cultivated land, ground of fruit is more than 200,000 mu, immigrants reach the highland by the storehouse, will destroy the ecological environment, the still water weakens the sewage self-purification ability, worsen water quality, influence reproduction of the wild animal,etc. in the reservoir. So is both advantageous and disadvantageous, do not hinder building the Three Gorges Projects. Should reduce being unfavorable to minimum extent, it is mainly that reservoir immigrants want to plant trees and grass, build the terraced fields, ecological environment protection, does not require the self-sufficiency of grain. Accomplish these, want making a great effort and fund. Control blowdown such as Chongqing,Fuling, Wan County, carry on sewage disposal, protect the water quality of the reservoir, protect the wild animal, set up the protection zone. Although ecological environment protection is difficult, must solve and can solve. As for the scenery of Sanxia, because the high near kilometer of rock bank, and Sanxia dam is only in fact higher than the river surface 110 meters. The scenery basically remains unchanged, the high gorge produces Pinghu, increase even more beautifully.Six. Immigrant's question in the reservoir areaThe reservoir of Sanxia will flood 632 sq. km. of land area, will involve Chongqing, 20 county (market) of Hubei. The reservoir of Sanxia floods and involves 2 cities, 11 county towns, 116 market towns; Flood or flood 1599 of industrial and mining enterprises that influence, reservoir flood line there are 24,500 hectares of cultivated land in all; Flood 824.25 kilometers of highways, 92,200 kilowatts of power stations; The area of house of flooding area is 34,596,000 square meters, total population of living in the flooding area is 844,100 people (agricultural population 361,500 people among them). Consider population growth and other factors of moving etc. two times during construction, the total population of trends of reservoir immigration allocation of Sanxia will be up to 1,130,000 people. The task is arduous, but must find a room for good immigrants, make its life improve to some extent, help immigrants to create the working condition, live plainly and struggle hard through 20 years, grow rich. Most immigrants retreat to the highland, it is nonlocal that some immigrants get. The reservoir of Sanxia will flood 632 sq. km. of land area, will involve Chongqing, 20 county (market) of Hubei. The reservoir of Sanxia floods and involves 2 cities, 11 county towns, 116 market towns; Flood or flood 1599 of industrial and mining enterprises that influence, reservoir flood line own cultivated land (suck the ground of mandarin orange) 24,500 hectares in common; Flood 824.25 kilometers of highways, 92,200 kilowatts of power stations; The area of house of flooding area is 34,596,000 square meters, The total population of living in the flooding area is 844,100 people (agricultural population 361,500 people among them). Consider population growth and other factors of moving etc. two times during construction, the total population of trends of reservoir immigration allocation of Sanxia will be up to 1,130,000 people.1.exploration and opening of the immigrants in SanxiaThe exploration of an immigrant in Sanxia and open country are in the engineering construction of Sanxia, implement immigrant's policy of the exploration, relevant people's governments organize and lead immigrants to arrange work, use immigrant's funds in a unified manner, exploit natural resources rationally, based on agriculture, the agriculture,industry and commerce combine, through many channel, many industries, multi-form, many method find a room for immigrants properly, immigrants' living standard reach or exceed originally and competently, and create the condition for long-term economic development and improvement of immigrant's living standard of reservoir area of Three Gorges. Immigrant's policy of the exploration, is a great reform of the reservoir immigrants of our country. Policy this, and reservoir area of Three Gorges immigrant put forward at the foundation of pilot project eight year in experience and lessons that immigrant work since new China set up of summarizing. At the beginning of reservoir immigrants in Sanxia, carry out exploration immigrants' principles and policies, insist the country supports, the policy is favourable, each side supports, principle of relying on one's own efforts, appeared by the government, develop local resources in a planned way, expand the capacity of placing, help, offer service of forming a complete set, wide to open up, produce the life way, make it reach " take out offing, goal that so steady as to live, can get rich progressively ". Meanwhile, the country approves reservoir area of Three Gorges as " the open economic region of Sanxia ", enjoy some special policies opening to the outside world in the coastal area, call the immigrants in Sanxia of the developed coordinated cooperation of province and city, immigrant's enterprises and relevant The factor of production has been pushed to the broader large market. The governments at all levels of reservoir area of Three Gorges have issued some development coordinated cooperation, favourable measure inviting outside investment too. Reservoir area immigrant demonstrate with open to urge, develop, in order to develop, urge benign situation that place.2. reorganization and expansion of the immigrants in SanxiaThe reorganization of immigrants in Sanxia and the expansion immigrants in Sanxia are that one involve undertaking that the society of reservoir area reconstruct,resources are recombinated, the recombinating is one of the prominent characteristics of the immigrants in Sanxia, move the fundamental difference duplicated with traditional simple compensation immigrants, former state too. Implement immigrant's policy of the exploration, must demand to combine immigrants to move, reconfigure the factor of production, thus improve the disposition efficiency of resources, form new productivity. Expand while being what is called, expansion of scale, improvement of structure even more, function strengthen improvement of quality. Look with the view of development economics and implement the course of exploration immigrants, it is the course of economic expansion of reservoir area. Exploration immigrants begin from expanding, and ending at realizing expanding, the course that the whole immigrant move and rebuild one's home is running through economic expansion, full of to the yearning that expands in the future. Certainly, in actual operation, should set out from immigrant's reality to pay attention to all, insist reason is expanded.Seven. Investment and benefit questionInvests 90,090 million yuan (1993 price) in investment and the Three Gorges Projects static behavior of benefit question, invests more than about 200 billion yuan dynamically while finishing in project. The investment source of the Three Gorges Projects is as follows, state loan, state-run hydropower station each of price of electricity raise the price 0.4-0.7 fen, power station electric rate income of Ge Zhou Ba, the electric rate income after the power station of Sanxia generates electricity wait for, the country has this financial resources to guarantee to invest in putting in place. About benefit, it is estimated it in ten years after the Three Gorges Projects is built up, total project investment principal and interest, unless including project fee and fee for immigration, can have repaid with electric rate income,it prevent flood, shipping,etc. share make the investment. And the Three Gorges Projects prevent flood, generate electricity, shipping,etc. benefit long-term, and enormous social benefit. Therefore, benefit of the Three Gorges Projects is very great, there is increase slightly to even make the investment, it is very rational too to repay service life to slightly lengthen.三峡水利枢纽工程一、坝址及基本枢纽布置三峡工程大坝坝址选定在宜昌市三斗坪，在已建成的葛洲坝水利枢纽上游约40km处。
混凝土大坝外文翻译
Comparison of Design and Analysis of Concrete Gravity DamABSTRACTGravity dams are solid concrete structures that maintain their stability against design loads from the geometric shape, mass and strength of the concrete.The purposes of dam construction may include navigation, flood damage reduction,hydroelectric power generation, fish and wildlife enhancement,water quality,water supply,and recreation.The design and evaluation of concrete gravity dam for earthquake loading must be based on appropriate criteria that reflect both the desired level of safety and the choice of the design and evaluation procedures.In Bangladesh, the entire country is divided into 3 seismic zones, depending upon the severity of the earthquake intensity. Thus, the main aim of this study is to design high concrete gravity dams based on the U.S.B.R. recommendations in seismic zone II of Bangladesh, for varying horizontal earthquake intensities from 0.10 g - 0.30 g with 0.05 g increment to take into account the uncertainty and severity of earthquake intensities and constant other design loads, and to analyze its stability and stress conditions using analytical 2D gravity method and finite element method. The results of the horizontal earthquake intensity perturbation suggest that the stabilizing moments are found to decrease significantly with the increment of horizontal earthquake intensity while dealing with the U.S.B.R. Recommended initial dam section, indicating endanger to the dam stability, thus larger dam section is provided to increase the stabilizing moments and to make it safe against failure. The vertical, principal and shear stresses obtained using ANSYS 5.4 analyses are compared with those obtained using 2D gravity method and found less compares to 2D gravity method, except the principal stresses at the toe of the gravity dam for 0.10 g - 0.15 g. Although, it seems apparently that smaller dam section may be sufficient for stress analyses using ANSYS 5.4, it would not be possible to achieve the required factors of safety with smaller dam section.It is observed during stability analyses that the factor of safety against sliding is satisfied at last than other factors of safety, resulting huge dam section to make it safe against sliding. Thus, it can be concluded that it would not be feasible to construct a concrete gravity dam for horizontal earthquake intensity greater than 0.30 g without changing other loads and or dimension of the dam and keeping provision for drainage gallery to reduce the uplift pressure significantly.Keywords: Comparison Concrete Gravity Dam Dam Failure Design Earthquake Intensity Perturbation Stability and Stress1.IntroductionBasically, a gravity concrete dam is defined as a structure,which is designed in such a way that its own weight resists the external forces. It is primarily the weight of a gravity dam whichprevents it from being overturned when subjected to the thrust of impounded water [1]. This type of structure is durable, and requires very little maintenance. Gravity dams typically consist of a non overflow section(s) and an overflow section or spillway. The two general concrete construction methods for concrete gravity dams are conventional placed mass concrete and RCC. Gravity dams, constructed in stone masonry, were built even in ancient times, most often in Egypt, Greece, and the Roman Empire [2,3].However, concrete gravity dams are preferred these days and mostly constructed. They can be constructed with ease on any dam site, where there exists a natural foundation strong enough to bear the enormous weight of the dam. Such a dam is generally straight in plan, although sometimes, it may be slightly curve. The line of the upstream face of the dam or the line of the crown of the dam if the upstream face in sloping, is taken as the reference line for layout purposes, etc. and is known as the “Base line of the Dam” or the “Axis of the Dam”. When suitable conditions are available, such dams can be constructed up to great heights. The ratio of base width to height of high gravity dams is generally less than 1:1.A typical cross-section of a high concrete gravity dam is shown in Figure . The upstream face may be kept throughout vertical or partly slanting for some of its length. A drainage gallery is generally provided in order to relieve the uplift pressure exerted by the seeping water.Purposes applicable to dam construction may include navigation, flood damage reduction, hydroelectric power generation, fish and wildlife enhancement, water quality, water supply, and recreation.Many concrete gravity dams have been in service for over 50 years, and over this period important advances in the methodologies for evaluation of natural phenomena hazards havecaused the design-basis events for these dams to be revised upwards. Older existing dams may fail to meet revised safety criteria and structural rehabilitation to meet such criteria may be costly and difficult. The identified causes of failure, based on a study of over 1600 dams [4] are: Foundation problems (40%), Inadequate spillway (23%), Poor construction (12%), Uneven settlement (10%), High poor pressure (5%), Acts of war (3%), Embankment slips (2%), Defective ma terials(2%), Incorrect operation (2%), and Earthquakes (1%).Other surveys of dam failure have been cited by [5], who estimated failure rates from 2×10-4to7 ×10-4per damyear based on these surveys.2.LoadsIn the design of gravity concrete, it is essential to determine the loads required in the stability and stress analyses. The forces which may affect the design are: 1) Dead load or stabilizing force; 2) Headwater and tailwater pressures; 3) Uplift; 4) Temperature; 5) Earth and silt pressures; 6) Ice pressure; 7) Earth quake forces; 8) Wind pressure; 9) Subatmospheric pressure; 10) Wave pressure, and 11) Reaction of foundation.The seismic safety of such dams has been a serious concern since damage to the Koyna Dam in India in 1967 which has been regarded as a watershed event in the development of seismic analysis and design of concrete gravity dams all over the world. It is essential that those responsible must implement policies and proce dures to ensure seismic safety of dams through sound professional practices and state-of-the-art in related technical areas. Seismic safety of dams concerns public safety and therefore demands a higher degree of public confidence. The Estimations and descriptions of various forces are provided briefly in the following sections.2.1. Water PressureWater pressure (P) is the most major external force acting on gravity dams. The horizontal water pressure exerted by the weight of water stored on the upstream and downstream sides of the dam can be estimated from the rule of hydrostatic pr essure distribution and can be expressed bywhere, H is the depth of water and w γis the unit weight of water.2.2. Uplift PressureWater seepage through the pores, cracks and fissures of the foundation materials, and water seepage through dam body and then to the bottom through the joints between the body of the dam and its foundation at the base exert an uplift pressure on the base of the dam. According to the [6], the uplift pressure intensities at the heel and toe of the dam should be taken equal to their respective hydrostatic pressures and joined the intensity ordinates by a straight line. When drainage galleries are provided to relieve the uplift, the recommended uplift at the face of the gallery is equal to the hydrostatic pressure at toe plus 1/3rd of the difference between the 221H p w γ=hydrostatic pressures at the heel and the toe, respectively.2.3. Earthquake ForcesAn earthquake produces waves, which are capable of shaking the earth upon which the gravity dams rest, in every possible direction. The effect of an earthquake is, therefore, equivalent to imparting acceleration to the foundations of the dams in the direction in which the wave is traveling at the moment.Generally, an earthquake induces horizontal acceleration (h) and vertical acc eleration (v). The values of these accelerations are generally expressed as per centage of the acceleration due to gravity (g), i.e.,= 0.10 g or 0.20 g, etc. On an average, a value of equal to 0.10 to 0.15 g is generally sufficient for high dams in seismic zones. In extremely seismic regions and in conservative Designs even a value up to 0.30 g may sometimes be adopted [7].Earthquake loadings should be checked for horizontal as well as vertical earth quake accelerations. While earthquake acceleration might take place in any direc tion,the analysis should be performed for the most unfavorable direction.The earthquake loadings used in the design of concrete gravity dams are based on design earthquakes and sitespecific motions determined from seismological eva luation. At a minimum, a seismological evaluation should be performed on all pro jects located in seismic zones 1, 2, and 3 of Bangladesh [8], depending upon the severity of earthquakes.The seismic coefficient method of analysis should be used in determining the resultant location and sliding stability of dams. In strong seismicity areas, a dynamic seismic analysis is required for the internal stress analysis.2.3.1. Effect of Vertical Acceleration (ɑv)A vertical acceleration may either act downward or upward. When it acts in the upward direction, then the foundation of the dam will be lifted upward and becomes closer to the body of the dam, and thus the effective weight of the dam will increase and hence, the stress developed will increase.When the vertical acceleration acts downward, the foundation shall try to move downward away from the dam body; thus, reducing the effective weight and the stability of the dam, and hence is the worst case for design. The net effective weight of the dam is given by (2) where, W is the total weight of the dam, kv is the fraction of gravity adopted for verticalacceleration, such as 0.10 or 0.20, etc. In other words, vertical acceleration reduces the unit weight of the dam material and that of water to (1 – kv) times their original unit weights.2.3.2. Effects of Horizontal Acceleration (ɑh))1(v v k w g k gw w -=-The horizontal acceleration may cause 1) hydrodynamic pressure, and 2) horizontal inertia force.1) Hydrodynamic Pressure: Horizontal acceleration acting towards the reservoir causes a momentary increase in the water pressure, as the foundation and dam acc elerate towards the reservoir and the water resists the movement owing to its ine rtia. According to [9], the amount of this hydrodynamic force (Pe) is given by(3) where, Cm = maximum value of pressure coefficient for a given constant slope = 0.735(0θ/ 90) θ , whereθis the angle in degree, which the upstream face of the dam makes wi th the horizontal; kh = fraction of gravity adopted for horizontal acceleration such as αh=kh ×gThe moment of this force about the base is given by(4) 2) Horizontal Inertia Force: In addition to exerting the hydrodynamic pressure, the horizontal acceleration produces an inertia force into the body of the dam. This force is generated to keep the body and the foundation of the dam together as one piece. The direction of the produced force will be opposite to the accele ration imparted by the earthquake.Since an earthquake may impart either upstream or downstream acceleration, it is needed to choose the direction of this force in the stability analysis of dam structure in such a way that it produces most unfavorable effects under the consid ered conditions. For example, when the reservoir is full, this force will produce worst results if it is additive to the hydrostatic water pressure, thus Acting towards the downstream (i.e., when upstream earthquake acceleration towards the reservoir is produced). When the reservoir is empty, this force would produce worst results, if considered to be acting upstream (i.when earthquake acceleration moving towards the downstream is produced.原文出自：/journal/PaperInformation.aspx?paperID=181852726.0H kC p w h m e γ=H P M e e 412.0=混凝土重力坝的设计分析与比较摘要重力坝是一种坚实的混凝土结构.大坝建设的目的可能包括通航,减少洪水造成的损失,水力发电,鱼类和野生动物养殖,蓄水灌溉等.混凝土重力坝的设计和评估地震荷载必须基于适当的标准,既能反映所需的安全级别，也要有设计的选择和评价程序.在孟加拉国,整个国家被分成3个地震带,这取决于地震强度的严重性.因此,本研究的主要目的是设计基于U.S.B.R高混凝土重力坝.在孟加拉国地震带二区,建议对不同水平地震强度从0.10g～0.30g 和0.50g增量考虑地震烈度，持续的不确定性和严重程度等其他来设计负荷。
水利类英文文献译文
Hand Move Irrigation SystemsSummaryThe ‘hand move’ irrigation system is a very simple pipe set which can be moved by hand. Two main factors-—positioning and moving scheme of the equipment both affect the work time. Here we develop a model to complete the irrigation of the whole field by the shortest time。
Firstly, we decide the certain number of sprinklers through the designated parameter。
Using enumerative geometry, we compare the irrigation area of the system with different number of sprinklers and work out the optimum number of sprinklers。
Secondly, we take the advantage of combinatorial geometry to decide the positioning and moving scheme of the irrigation system，in order that the model can be used to realize the irrigation task by the shortest work time.In the end we also introduce a new sprinkler with square area and compare its working efficiency with the traditional sprinkler if we use it on this field。
钢筋混凝土结构中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Reinforced ConcreteConcrete and reinforced concrete are used as building materials in every country. In many, including the United States and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced concrete construction stems from the wide availability of reinforcing bars and the constituents of concrete, gravel, sand, and cement, the relatively simple skills required in concrete construction, and the economy of reinforced concrete compared to other forms of construction. Concrete and reinforced concrete are used in bridges, buildings of all sorts underground structures, water tanks, television towers, offshore oil exploration and production structures, dams, and even in ships.Reinforced concrete structures may be cast-in-place concrete, constructed in their final location, or they may be precast concreteproduced in a factory and erected at the construction site. Concrete structures may be severe and functional in design, or the shape and layout and be whimsical and artistic. Few other building materials off the architect and engineer such versatility and scope.Concrete is strong in compression but weak in tension. As a result, cracks develop whenever loads, or restrained shrinkage of temperature changes, give rise to tensile stresses in excess of the tensile strength of the concrete. In a plain concrete beam, the moments about the neutral axis due to applied loads are resisted by an internal tension-compression couple involving tension in the concrete. Such a beam fails very suddenly and completely when the first crack forms. In a reinforced concrete beam, steel bars are embedded in the concrete in such a way that the tension forces needed for moment equilibrium after the concrete cracks can be developed in the bars.The construction of a reinforced concrete member involves building a from of mold in the shape of the member being built. The form must be strong enough to support both the weight and hydrostatic pressure of the wet concrete, and any forces applied to it by workers, concrete buggies, wind, and so on. The reinforcement is placed in this form and held in place during the concreting operation. After the concrete has hardened, the forms are removed. As the forms are removed, props of shores are installed to support the weight of the concrete until it has reached sufficient strength to support the loads by itself.The designer must proportion a concrete member for adequate strength to resist the loads and adequate stiffness to prevent excessive deflections. In beam must be proportioned so that it can be constructed. For example, the reinforcement must be detailed so that it can be assembled in the field, and since the concrete is placed in the form after the reinforcement is in place, the concrete must be able to flow around, between, and past the reinforcement to fill all parts of the form completely.The choice of whether a structure should be built of concrete, steel, masonry, or timber depends on the availability of materials and on a number of value decisions. The choice of structural system is made by the architect of engineer early in the design, based on the following considerations:1. Economy. Frequently, the foremost consideration is the overall const of the structure. This is, of course, a function of the costs of the materials and the labor necessary to erect them. Frequently, however, the overall cost is affected as much or more by the overall construction time since the contractor and owner must borrow or otherwise allocate money to carry out the construction and will not receive a return on this investment until the building is ready for occupancy. In a typical large apartment of commercial project, the cost of construction financing will be a significant fraction of the total cost. As a result, financial savings due to rapid construction may more than offset increased material costs. For this reason, any measures the designer can take to standardize the design and forming will generally pay off in reduced overall costs.In many cases the long-term economy of the structure may be more important than the first cost. As a result, maintenance and durability are important consideration.2. Suitability of material for architectural and structural function.A reinforced concrete system frequently allows the designer to combine the architectural and structural functions. Concrete has the advantage that it is placed in a plastic condition and is given the desired shape and texture by means of the forms and the finishing techniques. This allows such elements ad flat plates or other types of slabs to serve as load-bearing elements while providing the finished floor and / or ceiling surfaces. Similarly, reinforced concrete walls can provide architecturally attractive surfaces in addition to having the ability to resist gravity, wind, or seismic loads. Finally, the choice of size of shape is governed by the designer and not by the availability of standard manufactured members.3. Fire resistance. The structure in a building must withstand the effects of a fire and remain standing while the building is evacuated and the fire is extinguished. A concrete building inherently has a 1- to 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fireproofed to attain similar fire ratings.4. Low maintenance.Concrete members inherently require less maintenance than do structural steel or timber members. This is particularly true if dense, air-entrained concrete has been used forsurfaces exposed to the atmosphere, and if care has been taken in the design to provide adequate drainage off and away from the structure. Special precautions must be taken for concrete exposed to salts such as deicing chemicals.5. Availability of materials. Sand, gravel, cement, and concrete mixing facilities are very widely available, and reinforcing steel can be transported to most job sites more easily than can structural steel. As a result, reinforced concrete is frequently used in remote areas.On the other hand, there are a number of factors that may cause one to select a material other than reinforced concrete. These include:1. Low tensile strength.The tensile strength concrete is much lower than its compressive strength ( about 1/10 ), and hence concrete is subject to cracking. In structural uses this is overcome by using reinforcement to carry tensile forces and limit crack widths to within acceptable values. Unless care is taken in design and construction, however, these cracks may be unsightly or may allow penetration of water. When this occurs, water or chemicals such as road deicing salts may cause deterioration or staining of the concrete. Special design details are required in such cases. In the case of water-retaining structures, special details and / of prestressing are required to prevent leakage.2. Forms and shoring. The construction of a cast-in-place structure involves three steps not encountered in the construction of steel or timber structures. These are ( a ) the construction of the forms, ( b ) the removal of these forms, and (c) propping or shoring the new concrete to support its weight until its strength is adequate. Each of these steps involves labor and / or materials, which are not necessary with other forms of construction.3. Relatively low strength per unit of weight for volume.The compressive strength of concrete is roughly 5 to 10% that of steel, while its unit density is roughly 30% that of steel. As a result, a concrete structure requires a larger volume and a greater weight of material than does a comparable steel structure. As a result, long-span structures are often built from steel.4. Time-dependent volume changes. Both concrete and steel undergo-approximately the same amount of thermal expansion and contraction. Because there is less mass of steel to be heated or cooled,and because steel is a better concrete, a steel structure is generally affected by temperature changes to a greater extent than is a concrete structure. On the other hand, concrete undergoes frying shrinkage, which, if restrained, may cause deflections or cracking. Furthermore, deflections will tend to increase with time, possibly doubling, due to creep of the concrete under sustained loads.In almost every branch of civil engineering and architecture extensive use is made of reinforced concrete for structures and foundations. Engineers and architects requires basic knowledge of reinforced concrete design throughout their professional careers. Much of this text is directly concerned with the behavior and proportioning of components that make up typical reinforced concrete structures-beams, columns, and slabs. Once the behavior of these individual elements is understood, the designer will have the background to analyze and design a wide range of complex structures, such as foundations, buildings, and bridges, composed of these elements.Since reinforced concrete is a no homogeneous material that creeps, shrinks, and cracks, its stresses cannot be accurately predicted by the traditional equations derived in a course in strength of materials for homogeneous elastic materials. Much of reinforced concrete design in therefore empirical, i.e., design equations and design methods are based on experimental and time-proved results instead of being derived exclusively from theoretical formulations.A thorough understanding of the behavior of reinforced concrete will allow the designer to convert an otherwise brittle material into tough ductile structural elements and thereby take advantage of concrete’s desirable characteristics, its high compressive strength, its fire resistance, and its durability.Concrete, a stone like material, is made by mixing cement, water, fine aggregate ( often sand ), coarse aggregate, and frequently other additives ( that modify properties ) into a workable mixture. In its unhardened or plastic state, concrete can be placed in forms to produce a large variety of structural elements. Although the hardened concrete by itself, i.e., without any reinforcement, is strong in compression, it lacks tensile strength and therefore cracks easily. Because unreinforced concrete is brittle, it cannot undergo large deformations under load and failssuddenly-without warning. The addition fo steel reinforcement to the concrete reduces the negative effects of its two principal inherent weaknesses, its susceptibility to cracking and its brittleness. When the reinforcement is strongly bonded to the concrete, a strong, stiff, and ductile construction material is produced. This material, called reinforced concrete, is used extensively to construct foundations, structural frames, storage takes, shell roofs, highways, walls, dams, canals, and innumerable other structures and building products. Two other characteristics of concrete that are present even when concrete is reinforced are shrinkage and creep, but the negative effects of these properties can be mitigated by careful design.A code is a set technical specifications and standards that control important details of design and construction. The purpose of codes it produce structures so that the public will be protected from poor of inadequate and construction.Two types f coeds exist. One type, called a structural code, is originated and controlled by specialists who are concerned with the proper use of a specific material or who are involved with the safe design of a particular class of structures.The second type of code, called a building code, is established to cover construction in a given region, often a city or a state. The objective of a building code is also to protect the public by accounting for the influence of the local environmental conditions on construction. For example, local authorities may specify additional provisions to account for such regional conditions as earthquake, heavy snow, or tornados. National structural codes genrally are incorporated into local building codes.The American Concrete Institute ( ACI ) Building Code covering the design of reinforced concrete buildings. It contains provisions covering all aspects of reinforced concrete manufacture, design, and construction. It includes specifications on quality of materials, details on mixing and placing concrete, design assumptions for the analysis of continuous structures, and equations for proportioning members for design forces.All structures must be proportioned so they will not fail or deform excessively under any possible condition of service. Therefore it is important that an engineer use great care in anticipating all the probableloads to which a structure will be subjected during its lifetime.Although the design of most members is controlled typically by dead and live load acting simultaneously, consideration must also be given to the forces produced by wind, impact, shrinkage, temperature change, creep and support settlements, earthquake, and so forth.The load associated with the weight of the structure itself and its permanent components is called the dead load. The dead load of concrete members, which is substantial, should never be neglected in design computations. The exact magnitude of the dead load is not known accurately until members have been sized. Since some figure for the dead load must be used in computations to size the members, its magnitude must be estimated at first. After a structure has been analyzed, the members sized, and architectural details completed, the dead load can be computed more accurately. If the computed dead load is approximately equal to the initial estimate of its value ( or slightly less ), the design is complete, but if a significant difference exists between the computed and estimated values of dead weight, the computations should be revised using an improved value of dead load. An accurate estimate of dead load is particularly important when spans are long, say over 75 ft ( 22.9 m ), because dead load constitutes a major portion of the design load.Live loads associated with building use are specific items of equipment and occupants in a certain area of a building, building codes specify values of uniform live for which members are to be designed.After the structure has been sized for vertical load, it is checked for wind in combination with dead and live load as specified in the code. Wind loads do not usually control the size of members in building less than 16 to 18 stories, but for tall buildings wind loads become significant and cause large forces to develop in the structures. Under these conditions economy can be achieved only by selecting a structural system that is able to transfer horizontal loads into the ground efficiently.钢筋混凝土在每一个国家，混凝土及钢筋混凝土都被用来作为建筑材料。
08水利专业混凝土重力坝毕业论文中英文资料外文翻译文献
混凝土重力坝中英文资料外文翻译文献混凝土重力坝基础流体力学行为分析摘要：一个在新的和现有的混凝土重力坝的滑动稳定性评价的关键要求是对孔隙压力和基础关节和剪切强度不连续分布的预测。
本文列出评价建立在岩石节理上的混凝土重力坝流体力学行为的方法。
该方法包括通过水库典型周期建立一个观察大坝行为的数据库，并用离散元法（DEM）数值模式模拟该行为。
一旦模型进行验证，包括岩性主要参数的变化，地应力，和联合几何共同的特点都要纳入分析。
斯威土地，Albigna 大坝坐落在花岗岩上，进行了一个典型的水库周期的特定地点的模拟，来评估岩基上的水流体系的性质和评价滑动面相对于其他大坝岩界面的发展的潜力。
目前大坝基础内的各种不同几何的岩石的滑动因素，是用德国马克也评价模型与常规的分析方法的。
裂纹扩展模式和相应扬压力和抗滑安全系数的估计沿坝岩接口与数字高程模型进行了比较得出，由目前在工程实践中使用的简化程序。
结果发现，在岩石节理，估计裂缝发展后的基础隆起从目前所得到的设计准则过于保守以及导致的安全性过低，不符合观察到的行为因素。
关键词：流体力学，岩石节理，流量，水库设计。
简介：评估抗滑混凝土重力坝的安全要求的理解是，岩基和他们上面的结构是一个互动的系统，其行为是通过具体的材料和岩石基础的力学性能和液压控制。
大约一个世纪前，Boozy大坝的失败提示工程师开始考虑由内部产生渗漏大坝坝基系统的扬压力的影响，并探讨如何尽量减少其影响。
今天，随着现代计算资源和更多的先例，确定沿断面孔隙压力分布，以及评估相关的压力和评估安全系数仍然是最具挑战性的。
我们认为，观察和监测以及映射对大型水坝的行为和充分的仪表可以是我们更好地理解在混凝土重力坝基础上的缝张开度，裂纹扩展，和孔隙压力的发展。
图.1流体力学行为：（一）机械;（二）液压。
本文介绍了在过去20个来自Albigna大坝，瑞士，多年收集的水库运行周期行为的代表的监测数据，描述了一系列的数值分析结果及评估了其基础流体力学行为。
水利电力英文翻译英文+中文
水利电力英文翻译英文+中文An overflow spillway is a section of dam designed to permit water to pass over its crest. Overflow spillways are widely used on gravity, arch, and buttress dams. Some earth dams have a concrete gravity section designed to serve as a spillway. The design of the spillway for tow dams is not usually critical, and a variety of simple crest patterns are used. In the case of large dams it is important that the overflowing water be guided smoothly over the crest with a minimum of turbulence. If the overflowing water breaks contact with the spillway surface, a vacuum will form at the point of separation and cavitations may occur. Cavitations plus the vibration from the alternates making and breaking of contact between the water and the face of the dam may result in serious structural damage.Cavities filled with vapor, air, and other gases will form in a liquid whenever the absolute pressure of the liquid is close to the vapor pressure. This phenomenon, cavitations, is likely to occur where high velocities cause reduced pressure. Such conditions may arise if the walls of a passage are so sharply curved as to cause separation of flow from the boundary. The cavity, on moving downstream, may enter a region where the absolute is much higher. This causes the vapor in the cavity to condense and return to liquid with a resulting implosion, or collapse, extremely high pressure result. Some of the implosive activity will occur at the surfaces of the passage and in the crevices and pores of the boundary material. Under a continual bombardment of these implosions, the surface undergoes fatigue failure and small particles are broken away, giving the surface a spongy appearance. This damaging action of cavitations is called pitting. The ideal spillway would take the form of the underside of the napped of a sharp-crested weir when the flow rate corresponds to the maximum design capacity of the spillway. More exact profiles may be found in more extensive treatments of the subject. The reverse curve on the downstream face of the spillway should be smooth and gradual; A radius of about one-fourth of the spillway height has proved satisfactory. Structural design of an ogee spillway is essentially the same as the design of a concrete gravity section. The pressure exerted on the crest of the spillway by the flowing water and the drag forces caused by fluid friction are usually small in comparison with the other forces acting on the section. The change in momentum of the flow in the vicinity of the reverse curve may, however, create a force which must be considered. The requirements of the ogee shape usually necessitate a thicker section than the adjacent no overflow sections.A saving of concrete can be effected by providing a projecting corbel on the upstream face to control the flow in outlet conduits through the dam, a corbel will interfere with gate operation. The discharge of an overflow spillway is given by the weir equation23C Q Lh ω= Where Q=discharge, or sec /3mt coefficien C =ωL=coefficienth=head on the spillway (vertical distance from the crest of the spillway to the reservoir level),mThe coefficient ωC varies with the design and head. Experimental models are often used to determine spillway coefficient. End contractions on a spillway reduce the effective length below the actual length L. Square-cornered piers disturb the flow considerably and reduce the effective length by the width of the piers plus about 0.2h for each pier.Streamlining the piers or flaring the spillway entrance minimizes the flow disturbance. If the cross-sectional area of the reservoir just upstream from the spillway is less than five times the area of flow over the spillway, the approach velocity with increase the discharge a noticeable amount. The effect of approach velocity can be accounted for by the equation2320g 2V h Q ⎪⎪⎭⎫ ⎝⎛+=L C ωwhere 0V is the approach velocity.PROPERTIES OF CONCRETEThe characteristics of concrete should be considered in relation to the quality for any given construction purpose. The closest practicable approach to perfection in every property of the concrete would result in poor economy under many conditions, and the most desirable structure is that in which the concrete has been designed with the correct emphasis on each of the various properties of the concrete, and not solely with a view to obtaining, say, the maximum possible strength.Although the attainment of the maximum strength should not be the sole criterion in design, the measurement of the crushing strength of concrete cubes or cylinders provides a means of maintaining a uniform standard of quality, and, in fact, is the usual way of doing so. Since the other properties of any particular mix of concrete are related to the crushing strength in some manner, it is possible that as a single control test it is still the most convenient and informative. The testing of the hardened concrete in prefabricated units presents no difficulty, since complete units can be selected and broken if necessary in the process of testing. Samples can be taken from some parts of a finished structure by cutting cores, but at consider one cost and with a possible weakening of the structure. It is customs, therefore, to estimate the properties of the concrete in the structure on the oasis of the tests made on specimens mounded from the fresh concrete as it is placed. These specimens are compacted and cured in a standard manner given in BS 1881 in 1970 as in these two respects it is impossible to simulate exactly the conditions in the structure. Since the crushing structure is also affected by the size and shape of a specimen or part of a structure, it follows that the crushing strength of a cube is not necessary the same as that of the mass of exactly the same concrete.Crushing strengthConcrete can be made having a strength in compression of up to about 80N/2mm ,or evenmore depending mainly on the relative proportions of water and cement, that is, the water/cement ratio, and the degree of compaction. Crushing strengths of between 20 and 50 mm at 28 days are normally obtained on the site with reasonably good supervision, for N/2mixes roughly equivalent to 1:2:4 of cement: sand: coarse aggregate. In some types of precastmm at 28 days are concrete such as railway sleepers, strengths ranging from 40 to 65 N/2obtained with rich mixes having a low water/cement ratio.The crushing strength of concrete is influenced by a number of factors in addition to the water/cement ratio and the degree of compaction. The more important factors are Type of cement and its quality. Both the rate of strength gain and the ultimate strength may be affected.Type and surface texture of aggregate. There is considerable evidence to suggest that some aggregates produce concrete of greater compressive and tensile strengths than obtained with smooth river gravels.Efficiency of curing. A loss in strength of up to about 40 per cent may result from premature drying out. Curing is therefore of considerable, importance both in the field and in the making of tests. The method of curing concrete test cubes given in BS 1881 should, for this reason, be strictly adhered to.Temperature In general, the rate of hardening of concrete is increased by an increase temperature. At freezing temperatures the crushing strength may remain low for some time.Age Under normal conditions increase in strength with age, the rate of increase depending on the type of cement with age. For instance, high alumina cement produces concrete with a crushing strength at 21 hours equal to that of normal Portland cement concrete at 28 days. Hardening continues but at a much slower rate for a number of years.The above refers to the static ultimate load. When subjected to repeated loads concrete fails at a load smaller than the ultimate static load, a fatigue effect. A number of investigators have established that after several million cycles of loading, the fatigue strength in compression is 50-60 per cent of the ultimate static strength.Tensile and flexural strengthThe tensile strength of concrete varies from one-eighth of the compressive strength at early ages to about one- twentieth later, and is not usually taken into account in the design of reinforced concrete structures. The tensile strength is, however, of considerable importance in resisting cracking due to changes in moisture content or temperature. Tensile strength tests are used for concrete roads and airfields.The measurement of the strength of concrete in direct tension is difficult and is rarely attempted. Two more practical methods of assessing tensile strength are available. One gives a measure of the tensile strength in bending, usually termed the flexural strength. BS 1881:1970 gives details concerning the making and curing of flexure test specimens, and of the method test. The standard size of specimen is 150m m×150m m×750m m long for aggregate of maximum size 40m m. If the largest nominal size of the aggregate is 20m m, specimens 100m m×100m m×750m m long may be used.A load is applied through two rollers at the third points of the span until the specimen breaks. The extreme fiber stresses, that is, compressive at the top and tensile at the bottom, can then be computed by the usual beam formulae. The beam will obviously fail in tension since the tensile strength is much lower than the compressive strength. Formulae for the calculation of the modulus of rupture are given in BS 1881:1970.Test specimens is the form of beams are sometimes used to measure the modulus of rupture or flexural strength quickly on the site. The two halves of the specimen may then be crushed so that besides the flexural strength the compressive strength can be approximately determined on the same sample. The test is described in BS 1881:1970.Values of the modulus of rupture are utilized in some methods of design of unreinforced concrete roads and runways, in which reliance is placed on the flexural strength of the concrete to distribute concentrated loads over a wide area.More recently introduced is a test made by splitting cylinders by compression across the diameter, to give what is termed the splitting tensile strength; Details of the method are given in BS 1881:1970.Values of the modulus of rupture are utilized in some methods of design of unreinforced concrete roads and runways, in which reliance is place on the flexural strength of the concrete to distribute concentrated loads over a wide area.More recently introduced is a test made by splitting cylinders by compression across the diameter, to give what is termed the splitting tensile strength; Details of the method are given in BS 1881:1970. the testing machine is fitted with an extra bearing bar to distribute the load along the full length of the cylinder Plywood strips, 12mm wide and 3mm thick are inserted between the cylinder and the testing machine bearing surfaces top and bottom.From the maximum applied load at failure the tensile splitting strength is calculated as follows:ld p 2f t π= Where =t f splitting tensile strength, N/2mmP=maximum applied load in Nl=length of cylinder in mmd=diameter in mmAs in the case of the compressive strength, repeated loading reduces the ultimate strength so that the fatigue strength in flexure is 50-60 per cent of the static strength.Shear strengthIn practice, shearing of concrete is always accompany compression and tension caused by bending, and even in testing is impossible to staminate an element of bending.RESERVOIRSWhen a barrier is constructed across some river in the form of a dam, water gets stored up on the upstream side of the barrier, forming a pool of water, generally called a reservoir.Broadly speaking, any water collected in a pool or a lake may be termed as a reservoir. The water stored in reservoir may be used for various purposes. Depending upon the purposes served, the reservoirs may be classified as follows:Storage or Conservation Reservoirs.Flood Control Reservoirs.Distribution Reservoirs.Multipurpose reservoirs.(1) Storage or Conservation Reservoirs. A city water supply, irrigation water supply or a hydroelectric project drawing water directly from a river or a stream may fail to satisfy the consumers’demands during extremely low flows, while during high flows; it may become difficult to carry out their operation due to devastating floods. A storage or a conservation reservoir can retain such excess supplies during periods of peak flows and can release them gradually during low flows as and when the need arise.Incidentally, in addition to conserving water for later use, the storage of flood water may also reduce flood damage below the reservoir. Hence, a reservoir can be used for controlling floods either solely or in addition to other purposes. In the former case, it is known as ‘Flood Control Reservoir’or ‘Single Purpose Flood Control Reservoir’, and in the later case, it is called a ‘Multipurpose Reservoir’.(2) Flood Control Reservoirs A flood control reservoir or generally called flood-mitigation reservoir, stores a portion of the flood flows in such a way as to minimize the flood peaks at the areas to be protected downstream. To accomplish this, the entire inflow entering the reservoir is discharge till the outflow reaches the safe capacity of the channel downstream. The inflow in excess of this rate is stored in stored in the reservoir, which is then gradually released so as to recover the storage capacity for next flood.The flood peaks at the points just downstream of the reservoir are thus reduced by an amount AB. A flood control reservoir differs from a conservation reservoir only in its need for a large sluice-way capacity to permit rapid drawdown before or after a flood.Types of flood control reservoirs. There are tow basic types of flood-mitigation reservoir.Storage Reservoir or Detention basins.Retarding basins or retarding reservoirs.A reservoir with gates and valves installation at the spillway and at the sluice outlets is known as a storage-reservoir, while on the other hand, a reservoir with ungated outlet is known as a retarding basin.Functioning and advantages of a retarding basin:A retarding basin is usually provided with an uncontrolled spillway and an uncontrolled orifice type sluiceway. The automatic regulation of outflow depending upon the availability of water takes place from such a reservoir. The maximum discharging capacity of such a reservoir should be equal to the maximum safe carrying capacity of the channel downstream. As flood occurs, the reservoir gets filled and discharges through sluiceways. As the reservoir elevation increases, outflow discharge increases. The water level goes on rising until the flood has subsided and the inflow becomes equal to or less than the outflow. After this, water gets automatically withdrawn from the reservoir until the stored water is completely discharged. The advantages of a retarding basin over a gate controlled detention basin are:①Cost of gate installations is save.②There are no fates and hence, the possibility of human error and negligence in their operation is eliminated.Since such a reservoir is not always filled, much of land below the maximum reservoir level will be submerged only temporarily and occasionally and can be successfully used for agriculture, although no permanent habitation can be allowed on this land.Functioning and advantages of a storage reservoir:A storage reservoir with gated spillway and gated sluiceway, provides more flexibility of operation, and thus gives us better control and increased usefulness of the reservoir. Storage reservoirs are, therefore, preferred on large rivers which require batter controlled and regulated properly so as not to cause their coincidence. This is the biggest advantage of such a reservoir and outweighs its disadvantages of being costly and involving risk of human error in installation and operation of gates.(3) Distribution Reservoirs A distribution reservoir is a small storage reservoir constructed within a city water supply system. Such a reservoir can be filled by pumping water at a certain rate and can be used to supply water even at rates higher than the inflow rate during periods of maximum demands (called critical periods of demand). Such reservoirs are, therefore, helpful in permitting the pumps or water treatment plants to work at a uniform rate, and they store water during the hours of no demand or less demand and supply water from their ‘storage’during the critical periods of maximum demand.(4) Multipurpose Reservoirs A reservoir planned and constructed to serve not only one purpose but various purposes together is called a multipurpose reservoir. Reservoir, designed for one purpose, incidentally serving other purpose, shall not be called a multipurpose reservoir, but will be called so, only if designed to serve those purposes also in addition to its main purpose. Hence, a reservoir designed to protect the downstream areas from floods and also to conserve water for water supply, irrigation, industrial needs, hydroelectric purposes, etc. shall be called a multipurpose reservoir.THE ELECTRIC POWER SYSTEMA great amount of effort is necessary to maintain an electric power supply within the requirement of the various types of customers served. Large investments are necessary, and continuing advancements in methods must be made as loads steadily increase from year to year. Some of the requirements for electric power supply are recognized by most consumers, such as proper voltage, availability of power on demand, reliability, and reasonable cost. Other characteristics, such as frequency, wave shape, and phase balance, are seldom recognized by the customer but are given constant attention by the utility power engineers.The voltage of the power supply at the customer’s service entrance must be held substantially constant. Variations in supply voltage are, from the customer’s view, detrimental in various respects. For example, below-normal voltage substantially reduces the light output from incandescent lamps. Above-normal voltage increase the light output but substantially reduces the life of the lamp. Motor operate at below-normal voltage draw abnormally high current and may overheat, even when carrying no more than the rated horsepower load. Over voltage on a motor may cause excessive heat loss in the iron of the motor, wasting energy and perhaps damaging the machine. Service voltages are usually specified by a nominal value and the voltage thanmaintained close to this value, deviating perhaps less than 5 percent above or below the nominal value. For example, in a 120-volt residential supply circuit, the voltage might normally vary between the limits of 115 and 125 volts as customer load and system conditions change throughout the day.Power must be available to the consumer in any amount that be may require from minute to minute. For example, motors may be turned on or off, without advance warning to the electric power company. As electrical energy cannot be stored (except to a limited extent in storage batteries), the changing loads impose severe demands on the control equipment of any electrical power system. The operating staff must continually study load patterns to predict in advance those major load changes that follow known schedules, such as the starting and shutting down of factories at prescribed hours each day.The demands for reliability of service increase daily as our industrial and social environment becomes more complex. Modern industry is almost locally dependent on electric power for its operation. Homes and office buildings are lighted, heated, and ventilated by electric power. In some instances loss of electric power may even pose a threat a life itself. Electric power, like everything else that is man-made can never be absolutely reliable. Occasional interruptions to service in limited areas will continue. Interruptions to large areas remain a possibility, although such occurrences may be very infrequent. Further interconnection of electric supply systems over wide areas, continuing development of reliable automated control systems and apparatus; provision of additional reserve facilities; and further effort in developing personnel to engineer, design, construct, maintain, and operate these facilities will continue to improve the reliability of the electric power supply.The cost of electric power is a prince consideration in the design and operation of electric power is a prime consideration in the design and operation of electric power system. Although the cost of almost all commodities has risen steadily over the past many years, the cost per kilowatt-hour of electrical energy has actually declined. This decrease in cost has been possible because of improved efficiencies of the generating stations and distribution systems. Although franchises often grant the electric power company exclusive rights for the supply of electric power to an area. There is keen competition between electric power and other forms of energy, particularly for heating and for certain heavy load industrial processes.The power supply requirements just discussed are all well known to most electric power users. There are, however, other specifications to the electric power supply which are so effectively handled by the power companies that consumers are seldom aware that such requirements are of importance.The frequency of electric power supply in the United States is almost entirely 60 hertz (formerly cycles per second). The frequency of a system is dependent entirely upon the speed at which the supply generator is rotated by its prime mover. Hence frequency control is basically a matter of speed control of the machines in the generating stations. Modern speed-control systems are very effective and hold frequency almost constant. Deviations are seldom greater than 0.02 hertz.In an ac system the voltage continually varies with time, at one instant being positive and a short time later being negative, going through 60 complete cycles of change in each second. Ideally a plot of the time change should be a sine wave.In poorly designed generating equipment, harmonics may be present and the wave shape maybe somewhat. The presence of harmonics produces unnecessary losses in the customer’s equipment and sometime produces hum in nearby telephone lines. The voltage wave shape is basically determined by the construction of the generation equipment. The power companies put specification limitations on the harmonic content of generator voltages and so require equipment manufactures to design and build their machines to minimize from this effect.ENVIRONMENT POLLUTIONThe existence of pollution in the environment, as a national and a world problem, was not generally recognized until the 1960s.Today many people regard pollution as a problem that will not go away, but one that could get worse in the future. It is increasingly being appreciated that the general effects of pollution produce a deterioration of the quality of the environment. This usually means that pollution is responsible for dirty streams, rivers and sea shorts, atmospheric contamination, the dissociation of the countryside, urban dereliction, affecting the environment in which people reside, work, and spend their leisure time.The present increasing emphasis upon pollution may create the impression that there has been a relatively sudden deterioration of the environment, that was not apparent twenty or thirty years ago. This is not the case. Pollution must have started at the time when man began to use the natural resources of the environment for his own benefit. At he began to develop a settled life in small communities, the activities of clearing trees, building shelter, cultivating crops, and preparing and cooking food must have altered the natural environment. Later, as the human population increased and became concentrated into large communities which developed craft skills. There were increasing quantities of human and animal waste and rubbish to be disposed of in the early days of man’s existence the amount of waste was small. It was disposed of locally and had virtually no effect upon the environment. Later, when large human settlements and towns were established, waste disposal began to cause obvious pollution of streets and water courses. In the thirteenth century the prevalence of cholera, typhus, typhoid and bubonic plague was associated with the lack of proper waste disposal methods. By themed-nineteenth century the population of the UK had increased to 22 million, and many canals and rivers were grossly polluted with sewage and industrial waste. Some sewerage systems existed in towns, but the collected sewage was discharged into the nearest river without ant treatment. Salmon had completely disappeared from the River Thames and outbreaks of cholera still occurred in London. A Royal Commission on the Prevention of River Pollution was established in 1857, and eventually the first preventive river pollution legislation was passed in 1876 and 1890. However, there was little significant improvement in pollution until after the First World War, and the condition of rivers had deteriorated again by the end of the Second World War. Even today, a number of British and continental coastal towns discharge almost untreated sewage into near-shore waters.The increasing pollution of land water was accompanied by air pollution. This must have begun as soon as man started to use wood fires to provide ‘space hosting’and a means of cooking food. Later surface, soft coal was discovered and used as a fuel, and records shown that coal smokes was a nuisance in London in the thirteenth century. In 1273,Edward I made the first ever anti-pollution law to prevent the use of coal for domestic heating, so smoke pollution has been recognized for at least 700 years. However, smoke pollution in London continued and isrecorded in both the sixteenth and seventeenth centuries. In the late eighteenth and throughout the nineteenth centuries there was a marked increase in air pollution, because of the greater use of coal by developing industry. From 1750, the chemical industry began to develop, and this caused the discharge of acid fumes into the smoky air of some manufacturing towns. A Royal Commission was set up in 1862 to consider air pollution and this resulted in the first Alkali Act in 1863, which set limits to the concentration of acid in discharged waste gases. However, the increasing domestic and industrial combustion of coal, and the production of piped coal gas from 1815, caused air pollution to steadily get worse. Large cities were particularly affected, and the well known 5 day smog incident in London in 1952 directly contributed to the deaths of 4000 people. As a result, the Beaver Committee on Air Pollution was established in 1953, and the Clean Air Act was passed in 1956. This was the first effective statute to provide the means of controlling atmospheric pollution.Noise pollution probably started when man first developed machines. The increase in industrial plants in the nineteenth century produce indoor noise pollution of the working environment for many factory and mill workers over a 6 day week. Outdoors, the development of private and public transport bright environmental noise, as the railway services came into use during the 1830s, motor transport from 1900, and regular aero plane services from 1922. during the first half of the twentieth century environmental noise considerably increased, but it was not recognized as pollution. Industrial and outdoor noise was designated as ‘nuisance’when the Noise Abatement Act was passed in 1960. Whereas the earlier increase in noise occurred in work places and in connection with transport, during the past thirty years noise has spread into the home and places of leisure and entertainment. Certainly the most rapid increase in environmental pollution has taken place during the last 150 years, and it has been attributed to a number of interrelating factors.THE CHARACTERISTICS OF FLUIDSA fluid is a substance which may flow, that is, its constituent particles may continuously change their positions relative to one another. Moreover, it offers no lasting resistance to the displacement, however great, of one layer over another. This means that, if the fluid is at rest, no shear force (that is a force tangential to the surface on which it acts) can exist in it. A solid, on the other hand, can resist a shear force while at rest, the shear force may cause some displacement of one layer over another, but the material does not continue to move indefinitely. In a fluid, however, shear forces are possible only while relative movement between layers is actually taking place. A fluid is further distinguished from a solid in that a given amount of it owes its shape at any particular time to that of a vessel containing it, or to forces which in some way restrain its movement.The distinction between solids and fluids is usually clear, but there are some substances not easily classified. Some fluids, for on the ground, but, although its flow would take place very slowly, yet over a period of time—perhaps several days—it would spread over the ground by the action of gravity, that is ,its constituent particle would change their relative positions. In the other hand, certain solids may be made to ‘flow’ when a sufficiently large force is applied, there are known as plastic solids.Even so, the essential difference between solids and fluids remains. Any fluid, no matter how。
水利水电工程专业土石坝的评估和修复毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：土石坝的评估和修复文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14附录一外文翻译英文原文Assessment and Rehabilitation of Embankment DamsNasim Uddin, P.E., M.ASCE1Abstract:A series of observations, studies, and analyses to be made in the field and in the office are presented to gain a proper understanding of how an embankment dam fits into its geologic setting and how it interacts with the presence of the reservoir it impounds. It is intended to provide an introduction to the engineering challenges of assessment and rehabilitation of embankments, with particular reference to a Croton Dam embankment.DOI: 10.1061/(ASCE)0887-3828(2002)16:4(176)CE Database keywords: Rehabilitation; Dams, embankment; Assessment.IntroductionMany major facilities, hydraulic or otherwise, have become very old and badly deteriorated; more and more owners are coming to realize that the cost of restoring their facilities is taking up a significant fraction of their operating budgets. Rehabilitation is, therefore, becoming a major growth industry for the future. In embankment dam engineering, neither the foundation nor the fills arepremanufactured to standards or codes, and their performance correspondingly is never 100% predictable. Dam engineering—in particular, that related to earth structures—has evolved on many fronts and continues to do so, particularly in the context of the economical use of resources and the determination of acceptable levels of risk. Because of this, therefore, there remains a wide variety of opinion and practice among engineers working in the field. Many aspects of designing and constructing dams will probably always fall within that group of engineering problems for which there are no universally accepted or uniquely correct procedures.In spite of advances in related technologies, however, it is likely that the building of embankments and therefore their maintenance, monitoring, and assessment will remain an empirical process. It is, therefore, difficult to conceive of a set of rigorous assessment procedures for existing dams, if there are no design codes. Many agencies (the U.S. Army Corps of Engineers, USBR, Tennessee Valley Authority, FERC, etc.) have developed checklists for field inspections, for example, and suggested formats and topics for assessment reporting. However, these cannot be taken as procedures; they serve as guidelines, reminders, and examples of what to look for and report on, but they serve as no substitute for an experienced, interested, and observant engineering eye. Several key factors should be examined by the engineer in the context of the mandate agreed upon with the dam owner, and these together with relevant and appropriate computations of static and dynamic stability form the basis of the assessment. It is only sensible for an engineer to commit to the evaluation of the condition of, or the assessment of, an existing and operating dam if he/she is familiar and comfortable with the design and construction of such things and furthermore has demonstrated his/her understanding and experience.Rehabilitation MeasuresThe main factors affecting the performance of an embankment dam are (1)seepage; (2)stability; and (3) freeboard. For an embankment dam, all of these factors are interrelated. Seepage may cause erosion and piping, which may lead to instability. Instability may cause cracking, which, in turn, may cause piping and erosion failures. The measures taken to improve the stability of an existing dam against seepage and piping will depend on the location of the seepage (foundation or embankment), the seepage volume, and its criticality. Embankment slope stability is usually improved by flattening the slopes or providing a toe berm. This slope stabilization is usually combined with drainage measures at the downstream toe. If the stability of the upstream slope under rapid drawdown conditions is of concern, then further analysis and/or monitoring of resulting pore pressures or modifications of reservoir operationsmay eliminate or reduce these concerns. Finally, raising an earth fill dam is usually a relatively straightforward fill placement operation, especi ally if the extent of the raising is relatively small. The interface between the old and new fills must be given close attention both in design and construction to ensure the continuity of the impervious element and associated filters. Relatively new materials, such as the impervious geomembranes and reinforced earth, have been used with success in raising embankment dams. Rehabilitation of an embankment dam, however, is rarely achieved by a single measure. Usually a combination of measures, such as the installation of a cutoff plus a pressure relief system, is used. In rehabilitation work, the effectiveness of the repairs is difficult to predict; often, a phased approach to the work is necessary, with monitoring and instrumentation evaluated as the work proceeds. In the rehabilitation of dams, the security of the existing dam must be an overriding concern. It is not uncommon for the dam to have suffered significantdistress—often due to the deficiencies that the rehabilitation measures are to address.The dam may be in poor condition at the outset and may possibly be in a marginally stable condition. Therefore, how the rehabilitation work may change the present conditions, both during construction and in the long term, must be assessed, to ensure that it does not adversely affect the safety of the dam. In the following text, a case study is presented as an introduction to the engineering challenges of embankment rehabilitation, with particular reference to the Croton Dam Project.Case StudyThe Croton Dam Project is located on the Muskegon River in Michigan. The project is owned and operated by the Consumer Power Company. The project structures include two earth embankments, a gated spillway, and a concrete and masonry powerhouse. The earth embankments of this project were constructed of sand with concrete core walls. The embankments were built using a modified hydraulic fill method. This method consisted of dumping the sand and then sluicing the sand into the desired location. Croton Dam is classified as a ‗‗h igh-hazard‘‘ dam and is in earthquake zone 1. As part of the FERC Part 12 Inspection (FERC 1993), an evaluation of the seismic stability was performed for the downstream slope of the left embankment at Croton Dam. The Croton Dam embankment was analyzed in the following manner. Soil parameters were chosen based on standard penetration (N) values and laboratory tests, and a seismic study was carried out to obtain the design earthquake. Using the chosen soil properties, a static finite-element study was conducted to evaluate the existing state of stress in the embankment. Then a one-dimensional dynamic analysis was conducted to determine the stress induced by the design earthquake shaking. The available strength was compared withexpected maximum earthquake conditions so that the stability of the embankment during and immediately after an earthquake could be evaluated. The evaluation showed that theembankment had a strong potential to liquefy and fail during the design earthquake. The minimum soil strength required to eliminate the liquefaction potential was then determined, and a recommendation was made to strengthen the embankment soils by insitu densification.Seismic EvaluationTwo modes of failure were considered in the analyses—namely, loss of stability and excessive deformations of the embankment. The following analyses were carried out in succession: (1) Determination of pore water pressure buildup immediately following the design earthquake; (2) estimation of strength for the loose foundation layer during and immediately following the earthquake; (3) analysis of the loss of stability for postearthquake loading where the loose sand layer in the embankment is completely liquefied; and (4) liquefaction impact analysis for the loose sand layer for which the factor of safety against liquefaction is unsatisfactory.Liquefaction Impact AssessmentBased on the average of the corrected SPT value and cyclic stress ratio (Tokimatsu and Seed 1987), a total settlement of the 4.6 m(15 ft) thick loose embankment layer due to complete liquefaction was found to be 0.23 m (0.75 ft).Permanent Deformation AnalysisBased on a procedure by Makdisi and Seed (1977), permanent deformation can be calculated using the yield acceleration, and the time history of the averagedinduced acceleration. Since the factor of safety against flow failure immediately following theearthquake falls well short of that required by FERC, the Newmark type deformation analysis is unnecessary. Therefore, it can be concluded that the embankment will undergo significant permanent deformation following the earthquake, due to slope failure in excess of the liquefaction-induced settlement of 0.23 m (0.75ft).Embankment RemediationBased on the foregoing results, it was recommended to strengthen the embankment by in situ densification. An analysis was carried out to determine the minimum soil strength required to eliminate the liquefaction potential. The analysis was divided into three parts, as follows. First, a slope stability analysis @using the computer program PCSTABL (Purdue 1988)# of the downstream slope of the left embankment was conducted. Strength and geometric parameters were varied in order to determine the minimum residual shear strength and minimum zone of soil strengthening required for a postearthquake stability factor of safety, (FS)>1.Second, SPT corrections were made. The minimum residual shear strength correlates to a corrected/normalized penetrationresistance value (N1) of 60. From this value, a backcalculation was performed to determine the minimum field measure standard penetration resistance N values (blows per foot). Third, liquefaction potential was reevaluated based on the minimum zone of strengthening and minimum strength in order to show that if the embankment is strengthened to the minimum value, then the liquefaction potential in the downstream slope of the left embankment will, for all practical purposes, be eliminated.ConclusionKey factors to be considered in dam assessment and rehabilitation are the completeness of design, construction, maintenance and monitoring records, and the experience, background, and competence of the assessing engineer. The paper presents a recently completed project to show that the economic realization of this type of rehabilitation inevitably rests to a significant degree upon the expertise of the civil engineers.ReferencesDuncan, J. M., Seed, R. B., Wong, K. S., and Ozawa, U. (1984). ‗‗FEADAM: A computer program for finite element analysis of dams.‘‘ GeotechnicalEngineering Research Rep. No. SU/GT/84-03,Dept. of Civil Engineering,Stanford Univ., Stanford, Calif.FERC. (1993). ‗‗Engineering guidelines for the evaluation of hydropower projects.‘‘ 0119-2.Makdisi, F. I., and Seed, H. B. (1977). ‗‗A simplified procedure forestimatingea rthquake induced deformations in dams and embankments.‘‘ Rep. No. EERC 77-19, Univ. of California, Berkeley, Calif.Purdue Univ. (1988). ‗‗PCSTABL: A computer program for slope stability analysis.‘‘ Rep., West Lafayette, Ind.Schnabel, P. B., Lysmer, J, an d Seed, H. B. (1972). ‗‗SHAKE: A computer program for earthquake response analysis of horizontally layered site.‘‘ Rep. No. EERC72-12, Univ. of California, Berkeley, Calif.Seed and Harder. (1990). ‗‗An SPT-based analysis of cyclic pore pressure generation and undrained residual strength.‘‘ Proc., H. Bolton Seed Memorial Symp., 2, 351–376.Tokimatsu, K., and Seed, H. B. (1987). ‗‗Evaluation of settlements of sands due to earthquake shaking.‘‘ J. Geotech. Eng., 113(8), 861–878.中文翻译土石坝的评估和修复摘要：在野外实地、办公室里已进行的一系列的观察，研究，分析，使本文获得了对石坝如何适应其地质环境，以及如何与水库相互影响的正确的认识。