地下工程外文翻译
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地铁隧道对相邻桩的承载力的影响摘要:在城市地区修建隧道需要考虑隧道施工对现有桩基础稳定性和完整性的影响。以广州地铁2号线为工程背景,我们集中分析了隧道施工地区对相邻桩基础承载能力的影响。它采用弹塑性三维有限差分模型,模拟地铁隧道施工全过程(土壤元素的失活和衬砌的激活)中桩的反应,利用快速拉格朗日分析对连续的三维坐标进行分析。隧道周围相邻的地层分为三个区域:第一区(隧道正上方地层),第二区(隧道侧上方45 地层)和第三区(隧道正侧方地层)。在每个地区选择一个典型的桩进行详细计算和分析。主要从桩侧摩阻力,桩端总抗力和桩底段轴力三方面对桩身承载力进行数值模拟。目前已经对不同地区对典型桩承载力的影响进行了理论值与实测值的对比分析。数值模拟结果表明,城市隧道施工对桩承载能力的影响主要取决于桩侧摩阻力和桩端总抗力。桩底位于隧道不同地层隧道施工对桩承载力的影响有很大不同,桩侧摩阻力和桩端总抗力因隧道施工发生复杂变化,从而表现为桩轴力的复杂变化,因而影响到桩基础的承载力。当桩基受扰动较大时,采用地层注浆加固或桩基托换等积极措施来控制桩基承载力和桩体沉降是十分必要的。研究结果对于类似的工程有参考价值。
关键字:隧道;数值模拟;桩基础;桩承载力;桩底段轴力;桩侧摩阻力;桩端总抗力。
1 引言
在城市地铁建设中,往往会遇到地铁隧道从高楼大厦的底部穿过的情况,这样必然会影响到建筑基础的稳定性和完整性,从而影响到高楼大厦的安全与稳定。基于此,对于因地铁施工引起的现存桩基承载力问题必须做出深入研究[1~5] 。
为了了解隧道开挖对现存桩基的影响,Morton和King已经进行了多次室内研究,与此同时Longanathan和他的同事曾进行离心试验的探讨。Chen和N.Longanathan 的研究采用相应的数值模拟分析重点分析了地铁施工对桩的影响,而对本文所研究的问题即浅埋暗挖地铁隧道近距施工引起的桩基承载力变化规律及相互效应问题的研究涉及很少,而这正是实际工程建设所遇到的急需进行深入研究的难题。
一个单桩的承载力存在如下关系:
Q=Qs+Qp ⑴
式中Q为桩基的承载力,Qs 为桩侧土的总摩阻力,Qp 为桩端土的总抗力。
由公式(1)可以看出,桩基的承载力由桩侧土的总摩阻力和桩端土的总抗力两部分组成。桩是通过桩侧摩阻力和端部抗力把上部荷载传递给地层的。如果隧道在桩基础的附近进行施工,必然会对桩的侧向摩阻力和端部抗力产生影响。因此,研究隧道地铁施工对桩基承载能力的影响和变化规律变得非常重要。
我们采用FLAC3D法,针对广州地铁2号线浅埋暗挖法施工的隧道对临近的桩基础承载能力的影响进行了数据分析。为了找到它们作用的原则和规律,我们对桩侧摩阻力,桩端总抗力和桩底段轴力进行了大量的深入研究。
2 工程背景
广州地铁2号线从某框架式结构桩基础的下面穿过,它采用浅埋暗挖法施工。它的基础是人工挖土端承桩。由于地质条件复杂,即作为持力层的中风化岩层发生交错倾斜现象,从而导致桩基础的长短和作用位置各不相同,如图1~2所示。由这两个图可知这项工
程相当复杂,因为桩基础与隧道的空间位置不能确定。评价隧道对已有桩基础承载了和稳定性的影响具有非常典型的代表意义。
(1)—人工填土层;(3–2)—冲洪积层~砂层;(5–2)—硬塑状残积层~粉质黏土;(6)—岩石全风化层;(7)—岩石强风化层;(8)—粉砂岩中等风化层;(9)—粉砂岩微风化层
图1工程地质纵剖面图
图2 桩与隧道位置关系
这些桩的直径是1.2米。隧道界面全部采用高7.3米,宽6.6米的椭圆形断面。初期衬砌厚度为0.3米,二次衬砌厚度为0.35米(如图3所示)。锚杆长2.5米,在隧道上部形成150度的覆盖区域。隧道分四个区域进行开挖。经过了相应的分析,我们找到了最佳的开挖顺序是1-2-3-4。
图3隧道截面开挖顺序图
3 数值计算模型
为便于问题的分析,计算模型以桩基础作用的地区为中心进行建模。它沿隧道纵向取为 100 m,沿隧道横向取为60 m,地表以下40 m为模型的底部边界。根据模型位移边界条件知,侧面水平位移和底部垂直位移是有限制的,模型上表面是自由的。模型的大小与群桩的水平位置之间的关系如图4所示。
图4隧道模型与群桩水平位置大小之间的关系
地层的初始应力可以通过如下方式得到:
第k层的垂直应力为:
其中k=1,2,……k;k=1,2,……;同时k≤模型的最大土层数;ρi=是土壤的饱和密度(广州的地下水位很浅),hi是土层的厚度。
如果我们假设k土层的泊松比为λk,那么土层的侧压力系数为:
侧向土压力为:
在分析中采用Mohr-Coulomb准则和大应变模型。屈服函数和塑性应变的函数如下:
式中,c 为岩土体的黏聚力,?为土体的内摩擦角,ψ为土体的膨胀角;p为平均应力, J2偏应力矢量,θ为Lode 角。
所有的物理和力学参数列于表1中。
表1 模型材料物理力学参数表
在这个工程中,准确的计算上部结构传递给桩上部的荷载非常的重要,它将最终决定桩的轴力和沉降量。工程中采用PKPM软件和工程估算法进行这些荷载的计算。由于PKPM软件考虑了地震因素和场地的实际状况,因此用PKPM软件计算的负载结果比工程估算法稍大一点儿。考虑工程的安全性,经过对两种方法计算结果的比较,采用了比较保守的PKPM软件计算的结果。
另外,还有一些关键问题需要解决:1)对复杂地层的准确定义,2)短开挖的模拟3)复杂衬砌施工的模拟。随着数值分析软件的发展这些问题都被一一解决了。
一些数值模型的信息标注在图5中。
(a)三维模型网格图
(b)隧道模型
图5数值计算模型
4 结果与讨论
很容易知道,隧道对周围岩体不同位置的干扰大小与隧道的开挖方法有关。为了便于分析,隧道周围岩体被分为三个区域,即,第一区(隧道正上方),第二区(隧道侧上方45?),第三区(隧道侧面)。因为建筑物的地基非常复杂而且桩基础桩长短不一,所以不可能对其进行一一研究。我们建议选取一些具有代表性的桩,以便对其进行详细深入的研究。考虑到三个分区域相邻的岩体和桩基础的特点,我们建议在每个分区域选取一个代表桩进行研究。
4.1 地层沉降,桩的位置与桩的应力之间的关系
通过统计分析手段,得到如图7所示的桩的应力与地层沉降的关系曲线,这表明隧道开挖对其周围的岩体产生了扰动,从而导致了其沉降和变形。这表明各岩层的沉降曲线是正态分布的。另外,越接近地面,沉降曲线振幅越大,峰值越小;相反,如果越远离地面,沉降曲线振幅越小,峰值越大。隧道下面地层产生隆起,由于
隧道开挖使桩基础在上部荷载作用下面产生较大的沉降,从而导致了桩周围岩体的附加沉降。因此,隧道、地层及桩基础之间是相互作用的,隧道开挖对桩基础产生了很大影响。
图6代表桩和岩层区
图7地层沉降和桩应力示意图
4.2 隧道施工对桩侧摩擦力和桩端阻力的影响分析
由图6和图7知,一区的沉降规律总结如下:沉降影响由下向上传递,沉降数值由下向上递减。桩A从地表穿越到隧道上部地层,成为上下地层的纽带。于是,下部地层首先发生沉降,并在桩A下部产生侧向拉力(负摩擦力),但因为上部地层沉降量小且滞后,会阻止桩A 下滑,故产生向上的侧摩擦力,即正摩擦力。因此在桩的中部有一个平衡点。在隧道中性点的上部为正摩擦区,中性点下部为负摩擦区,中性点处为拉力状态。下部持力地层的沉降量大于上部地层,从而导致桩A的端阻力减小。我们可以得出结论,由于此区域地层位移规律的特殊性,使位于第一区域内的桩基在侧摩擦力和端摩阻力方面出现与普通受力桩完全相反的受力状态,极大地降低了桩基承载力。桩A的受力如图7中箭头所示,其力的大小受隧道1、3部开挖的影响比较大,而受2、4部开挖的影响并不敏感。
第二区在沉降曲线的拐点范围内,下部地层的沉降量明显小于第一区地层的沉降量,且上部地层的沉降量变化缓慢。桩B的上部处于第一区的地层中,下部处于第二区的地层中;结果,桩B 上部受到第一区地层的较大沉降作用而产生向下的侧摩擦力(负摩擦阻力),而桩B的下部第二区地层沉降量相对较小,相对的阻止桩B 的下沉,产生向上的侧摩擦力(正摩擦阻力)。与施工前相比,中性点受压且其位置明显向下移动了。由于隧道上部侧向45°处围岩受到强烈的剪切应力作用,使得桩B底端轴力明显变大并超过了隧道施工前的初始值。轴向应力的增加剧了围岩的破坏,并诱发围岩产生了二次松动。桩B的应力如图7所标注的箭头所示,其力的大小受隧道1、3部开挖的影响比较大,而受2、4部开挖的影响并不敏感。
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Automobile Brake System汽车制动系统 The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal energy (heat).When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes. Two complete independent braking systems are used on the car. They are the service brake and the parking brake. The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal. The primary purpose of the brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set. The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. “Shoes” and “pads” are pushed by the slave cylinders to contact the “drums” and “rotors” thus causing drag, which (hopefully) slows the c ar. The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder (Figure). Basically, all car brakes are friction brakes. When the driver applies the brake, the control device forces brake shoes, or pads, against the rotating brake drum or disks at wheel. Friction between the shoes or pads and the drums or disks then slows or stops the wheel so that the car is braked.
安全工程专业英语词汇及翻译(司鹄版)
Unit6 Industry hygiene工业卫生physical hazard物理危害、物质危害nonionizing radiation非电离辐射adverse effects副作用loud noise嘈杂的声音chemical bum化学烧伤live electrical circuits 带电电路confined space密闭空间hearing loss听力丧失physical or mental disturbance身体或精神障碍annoyance烦恼power tools电动工具impulse脉冲sound level meter噪声计jet engine喷气式发动机time-weighted average时间加权平均heat stress热应力、热威胁shivering 颤抖hard labor辛苦工作fatigued疲劳的living tissue活组织plastic sealer塑料密封机biological hazard生物危害potable water饮用水sewage污水physical contact身体接触allergic reaction 过敏反应severe pain剧烈疼痛manual handing手工处理airborne空中的on a daily basis每天hazard communication standard危害通识规定stipulation规定、条款trade name商标名 工业卫生被定义为:“致力于预测、识别、评估和控制环境因素或压力的科学与技术,这些压力产生或来自与工作场所,能够造成疾病、损害人们的幸福安康、或是工程或社区居民的工作效率不高,并使他们感觉到很不舒服。(P67) 当噪音导致暂时或永久的听力丧失,使身体或精神发生紊乱,对语言交流产生干扰,或对工作、休息、放松、睡觉产生干扰时,它是一种非常严重的危害。噪音是任何不被期望的声音,它通常是一种强度变化但不包括任何信息的声音。他干扰人们对正常声音的辨别,可能是有害的,能使人烦恼,并干扰人们说话。(P68) Unit9 Accident investigation事故调查after-the-fact事实背后的take an investigation进行调查fact-finding process寻找事实的过程insurance carrier保险公司/承保人plance blame推卸责任permanent total disability永久全部劳动力丧失for simplicity为简单起见accident prevention 事故预防investigation procedures调查过程fact finding寻找事实operating procedures flow diagrams操作过程流程图maintenance chart维修图表bound notebook活页笔记本physical or chemical law物理或化学定律table of contens 目录narrative叙事的counter-measure干预措施 调查人员在调查过程中从各方面收集证据,从证人、旁观者及一些相关报道中得到信息,在事故发生后尽快的找目击证人谈话,在事故现场遭到改变前进行检查,对事故场景进行拍照并绘制草图,记录与地形相关的所有数据,并将所有的报道复印保存。记录常规的操作流程图、维修图表或对困难、异常现象的报告等非常有用。在活页笔记本中完整准确地记录。记录事故发生前的环境、事故顺序及事故发生后的环境情况等。另外,记录伤者、证人、机械能量来源和危害物质的位置。(P119) Unit10 Safety electricity安全用电electrical equipment电力设备fuse puller保险丝夹break contact断开接点/触电hot side高压端load side 负荷端line side线路/火线端groundfault circuit Interrupt 漏电保护器ground fault接地故障receptacle电源插座hot bubs热水澡桶underwater lighting水底照明fountains 人工喷泉ungrounded(hot)conductor 未接地(高压)单体/火线neutral conductor中性导体fault current载荷中心panelboard 配电板branch-circuit分支电路CB一种多功能插座plug-in插入式 上锁/挂牌成套设备也是可用的。上锁/挂牌套件中包含有必须满足OSHA上锁/挂牌标准的组件。上锁/挂牌套件中包含有可重复使用的危险标签、临时悬挂标志、各种闭锁、锁、磁性标志、及与上锁/挂牌相关的信息。无论什么原因停下工作或当天不能完成工作时,在返回
英语 安全工程专业翻译
Unit1 Safety Management Systems 1. Accident Causation Models The most important aim of safety management is to maintain and promote workers' health and safety at work. Understanding why and how accidents and other unwanted events develop is important when preventive activities are planned. Accident theories aim to clarify the accident phenomena,and to explain the mechanisms that lead to accidents. All modem theories are based on accident causation models which try to explain the sequence of events that finally produce the loss. In ancient times, accidents were seen as an act of God and very little could be done to prevent them. In the beginning of the 20th century,it was believed that the poor physical conditions are the root causes of accidents. Safety practitioners concentrated on improving machine guarding, housekeeping and inspections. In most cases an accident is the result of two things :The human act, and the condition of the physical or social environment Petersen extended the causation theory from the individual acts and local conditions to the management system. He concluded that unsafe acts, unsafe conditions,and accidents are all symptoms of something wrong in the organizational management system. Furthermore, he stated that it is the top management who is responsible for building up such a system that can effectively control the hazards associated to the organization’s
工程管理中英文对照外文翻译文献
中英文对照外文翻译文献 中英文对照外文翻译 The Internet is Applicated in Real Estate The Real Estate Industry and the World Wide Web: Changing Technology, Changing Location.The Internet, in its Web based graphics version, has captured the imagination of both consumers and businesses. Its convenience, speed, low cost and versatility are being exploited on a daily basis in ever-changing ways. Together with its capacity to transform existing businesses, promote new businesses and facilitate exchange of information and data, its other striking attribute has been the speed with which this new technology has spread throughout the global economy. Keywords:The internet;Real Estate;Applicated The number of computer hosts grew by more than ten-fold between 1995 and early 1999. The number of Web sites increased almost 100-fold, to over two million, between 1995 and 1998.By the year 2000, there will be approximately 400-500 million Internet users in the world, and the total number of Web sites will exceed five million. This new technology has the potential for affecting the real estate industry directly and indirectly. Directly, it may become a tool that allows a real estate business to expand its information and sales network. Indirectly, it may change the location equation where and how firms do business which in turn will affect the role of firms involved in real estate development, investment and transactions. Measuring the Spread of the Web
建筑-外文翻译
外文文献: Risk Analysis of the International Construction Project By: Paul Stanford Kupakuwana Cost Engineering Vol. 51/No. 9 September 2009 ABSTRACT This analysis used a case study methodology to analyse the issues surrounding the partial collapse of the roof of a building housing the headquarters of the Standards Association of Zimbabwe (SAZ). In particular, it examined the prior roles played by the team of construction professionals. The analysis revealed that the SAZ’s traditional construction project was generally characterized by high risk. There was a clear indication of the failure of a contractor and architects in preventing and/or mitigating potential construction problems as alleged by the plaintiff. It was reasonable to conclude that between them the defects should have been detected earlier and rectified in good time before the partial roof failure. It appeared justified for the plaintiff to have brought a negligence claim against both the contractor and the architects. The risk analysis facilitated, through its multi-dimensional approach to a critical examination of a construction problem, the identification of an effective risk management strategy for future construction projects. It further served to emphasize the point that clients are becoming more demanding, more discerning, and less willing to accept risk without recompense. Clients do not want surprise, and are more likely to engage in litigation when things go wrong. KEY WORDS:Arbitration, claims, construction, contracts, litigation, project and risk The structural design of the reinforced concrete elements was done by consulting engineers Knight Piesold (KP). Quantity surveying services were provided by Hawkins, Leshnick & Bath (HLB). The contract was awarded to Central African Building Corporation (CABCO) who was also responsible for the provision of a specialist roof structure using patented “gang nail” roof
2019年车辆工程专业毕业论文_外文翻译1.doc
Drive force control of a parallel-series hybrid system Abstract Since each component of a hybrid system has its own limit of performance, the vehicle power depends on the weakest component. So it is necessary to design the balance of the components. The vehicle must be controlled to operate within the performance range of all the components. We designed the specifications of each component backward from the required drive force. In this paper we describe a control method for the motor torque to avoid damage to the battery, when the battery is at a low state of charge. Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved. 1. Introduction In recent years, vehicles with internal combustion engines have increasingly played an important role as a means of transportation, and are contributing much to the development of society. However, vehicle emissions contribute to air pollution and possibly even global warming, which require effective countermeasures. Various developments are being made to reduce these emissions, but no further large improvements can be expected from merely improving the current engines and transmissions. Thus, great expectations are being placed on the development of electric, hybrid and natural gas-driven vehicles. Judging from currently applicable technologies, and the currently installed infrastructure of gasoline stations, inspection and service facilities, the hybrid vehicle, driven by the combination of gasoline engine and electric motor, is considered to be one of the most realistic solutions. Generally speaking, hybrid systems are classified as series or parallel systems. At Toyota, we have developed the Toyota Hybrid System (hereinafter referred to as the THS) by combining the advantages of both systems. In this sense the THS could be classified as a parallel-series type of system. Since the THS constantly optimizes engine operation, emissions are cleaner and better fuel economy can be achieved. During braking, Kinetic energy is recovered by the motor, thereby reducing fuel consumption and subsequent CO 2 emissions. Emissions and fuel economy are greatly improved by using the THS for the power train system. However, the THS incorporates engine, motor, battery and other components, each of which has its own particular capability. In other words, the driving force must be generated within the limits of each respective component. In particular, since the battery output varies greatly depending on its level of charge, the driving force has to be controlled with this in mind. This report clarifies the performance required of the respective THS components based on the driving force necessary for a vehicle. The method of controlling the driving force, both when the battery has high and low charge, is also described. 2. Toyota hybrid system (THS) [1,2] As Fig. 1 shows, the THS is made up of a hybrid transmission, engine and battery. 2.1. Hybrid transmission The transmission consists of motor, generator, power split device and reduction gear. The power split device is a planetary gear. Sun gear, ring gear and planetary carrier are directly connected to generator, motor and engine, respectively. The ring gear is also connected to the reduction gear. Thus, engine power is split into the generator and the driving wheels. With this type of mechanism, the