拓宽路基变形数值分析

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上海交通大学硕士学位论文
英文摘要
NUMERICAL ANALYSIS THE SUBGRADE DEFORMATION OF SUBGRADE WIDENING
ABSTRACT
With the sustained and rapid development of China national economy, road traffic is constantly increasing. The original road construction can’t meet the increasing traffic demands, and need to be broadened urgently. Due to the different characteristic and different consolidation extent and compression between new roads and old ones, differential settlement appears between them,which lead to vertical and horizontal cracks ,damage and elevation at new-old fringe zone and road surface. Therefore, the analysis of new and old roadbed deformation on the widening project is critical. In this paper, the finite difference software FLAC is used to analyse interaction between new and old roadbed. Geogrid deal is applied to the new-old fringe zone. For the cases of geogrid deal to new-old roadbed fringe zone,pipes reinforcement to soft soil and pile-supported roadbed, the new and old roadbed settlement, lateral displacement and differential settlement were systematic analysed. Following is the research results: 1.The software FLAC was used to establish the typical soft soil roadbed widening project numerical model. The interaction between new and old roadbeds was analysed,and the impact of the width of roadbed, filling height, filling weight,filling modulus on the roadbed deformation was studied.The result showed that the new roadbed increased the settlement of old roadbed.The greater the width of roadbed, filling height, the larger the differential settlement. The greater filling modulus and the smaller filling weight, the differential settlement was smaller. According to the differential settlement of widen roadbed and treatment measures of combination, soft soil treatment program was chosen in the widening project. 2.In order to analyze the measures of combination of new and old roadbed ,the Geogrid of software is used to simulation and analysis the subsidence and deformation of inhibition provided by the Geogrid ,which laid on combination of new and old roadbed. Study rule of roadbed settlementthe influenced by the different
上海交通大学 硕士学位论文 拓宽路基变形数值分析 姓名：张磊 申请学位级别：硕士 专业：岩土工程 指导教师：徐永福;王峰 20090101
上海交通大学硕士学位论文
中文摘要
拓宽路基变形数值分析 摘 要
随着我国国民经济持续快速发展，道路交通量不断增加，原建道路不能满足 日益增加的交通量要求， 迫切需要拓宽改造。 由于拓宽后新老路基本身性状不同、 新老路基地基固结程度和压缩量不同，引起新老路基间产生差异沉降，导致新老 路基结合部和路面出现纵向裂缝。因此，分析拓宽工程中新老路基协调变形对拓 宽工程建设是至关重要的。 本文采用 FLAC 有限差分软件分析新老路堤间的相互 作用，针对新老路堤结合部采用土工格栅处理，桩加固软土地基和桩承式路堤， 系统分析了新老路基沉降、侧向位移和差异沉降，取得了以下研究成果： 1.采用 FLAC 建立典型软土路基拓宽工程数值模型，分析新拓宽路基与老路 基的相互作用，研究拓宽宽度、填筑高度、填土重度和填土模量对路基变形的影 响。计算结果发现，拓宽工程中，新路堤增加了老路堤的沉降，拓宽宽度、填土 高度和填土重度越大，差异沉降越大；填土模量越大，填土重度越小，差异沉降 越小， 根据拓宽路基差异沉降为选择结合部处治措施和选取拓宽工程中软基处理 方案提供依据。 2.采用 FLAC 软件中的土工格栅单元，模拟分析新老路堤拓宽结合部铺设的 土工格栅对新老路基差异沉降和变形的抑制作用， 分别研究了土工格栅的不同铺 设方式和层间距对路基沉降的影响规律。计算结果发现：采用全路堤铺设或一端 固定的方式，获得理想的效果；路基的差异沉降随着层间距的减小而减小，层间 距在 1m 时加固效果最好；格栅模量越大，差异沉降越小。计算结果为确定新老 路堤结合部铺设土工格栅层数和方式提供依据。 3.选用软件中 Pile 单元，研究桩加固软土路基的沉降和桩体受力特性的影响。计算结果发现： 桩越长，特别是桩身穿透软土层，路基差异沉降、侧向变形越小；桩间距越小， 路基变形也越小；通过增大模量能起到良好的加固效果。通过对比发现，三者之
III
上海交通大学硕士学位论文
英文摘要
paving method and the spacing of Geogrid. The caculation showed that the desired results was gotten by using full roadbed laying method or one end fixed method.The differential settlement decreased with layer distance decreased.Perfect economic consolidation effect could be gotten when the layer distance reached the critical value-one meter.The greater the geogrid modulus,the smaller the differential settlement. According to the calculation results,the layer floors of geogrid and laying method was determined at the new-old fringe zone. 3.Study the settlement and pile stress characteristics of pile strengthening soft subgrade and systematic analysis the influence of pile length,pile spacing and pile modulus on the settlement and deformation on widen subgrade ,by slecting the pile element and changing pile modulus.The caculation results show that: the longer the pile is， the less the differential settlement and lateral deformation happens , especially when the pile penetrates the soft soil layer;with the pile spacing decreases,the subgrade deformation also decreases ;the increasing of modulus has good effect on subgrade paring the three factors,pile length has the most important influence on subgrade deformation. 4.Analysis the law of settlement and deformation of pile-supported reinforced embankment and research the effect of pile top cushion modulus and cancellus height on subgrade deformation by chaging the modulus and height of pile top geotechnical cancellus. The caculation results show that: with the increase of cancellus ,the subgrade settlement decrease gradually when the modulus is given;with the increase of mudulus,the maximum settlement and differential settlement obviously reduces.