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华東交通大学 工程硕士学位论文
某建筑基坑施工对临近地铁车站及周边土层 影响的研究
学位申请人: 徐腾飞学科领域: 建筑与土木工程校内导师: 耿大新教授校外导师:
华东交通大学216届工程硕士学位论文 某建筑基坑施工对临近地铁车站及周边土层影响的研究 土术建筑学院 万方数据
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某建筑基坑施工对临近地铁车站及周边土层影响的研究
摘要
随着城市化进程的不断加快,城市用地愈加紧张,基坑工程的优势逐渐突出.目前,城市基坑工程多处于繁华地段,不可避免地在临近地铁车站结构附近施工.基坑开挖是一个卸载的过程,基坑开挖会对地铁车站结构及周边地层造成影响.本文以南昌市某建筑基坑工程为实例,采用MIDAS/GTS有限元软件,建立考虑周边环境的三维有限元模型,对开挖施工过程进行数值模拟.对基坑开挖过程中对临近地铁车站结构及周边环境的影响规律进行总结,并将数值模拟结果与现场实测数据进行对比,验证模型正确性:同时以该工程为依托,分别针对基坑开挖工序、基坑围护桩桩径和基坑开挖深度三种因素,对既有地铁车站结构及周边土体的影响进行分析,分别设置四种基坑开挖工序、五种不同桩径(0.5R~1.5R)及五种不同基坑开挖深度(0.5H~2.5H),对不同工况下的基坑开挖对临近地铁车站结构竖向位移、围护桩深层水平位移和周边地表竖向位移进行对比分析,得到基坑开挖对临近地铁车站结构及周边环境的影响规律,为类似工程提供参考,主要结论如下:
(1)通过基坑开挖对临近地铁车站的影响进行分析可知,随着基坑的逐层开挖,地铁车站结构会出现上浮趋势,且随开挖的进行不断呈现增长趋势,尤其当开挖靠近车站一侧的土体,其水平位移和竖向位移呈明显增大趋势.
(2)不同开挖工序对临近地铁车站的影响不同.在基坑开挖过程中,应根据基坑的形状、支护结构的位置等情况,分区域、分块合理安排施工工序,进而减少对车站结构变形的影响(本工程中建议采用先开挖两侧,后开挖中间的施工工序进行开挖).
(3)围护桩水平方向变形与基坑开挖深度紧密相关,在基坑开挖完成时,坑底底板及坑内支撑施作对控制围护桩的水平方向变形具有明显效果,且围护桩长度宜为基坑开挖深度的1.5~2.0倍.
关键词:基坑工程、地铁车站、数值模拟、地表沉降
StudyontheperformanceofSubwaystation effectedbyadjacentbuildingfoundationpit
Abstract
With the accelerating pace of urbanization urban land is being more andmore pact and the advantages of foundation pit engineering are graduallyprominent. At present most of the foundation pit projects are located in busy streets which are inevitably constructed near the structure of the Metro station. Foundationstructure of metro station and surrounding strata. For this reason this paper uses pit excavation is a unloading process and excavation will inevitably affect theMIDAS/GTS finite element software to build a three-dimensional finite elementmodel considering the surrounding environment and to simulate the excavationprocess. This paper summarizes the influence law of the structure and surroundingenvironment of the nearby metro station during the excavation of foundation pit andpares the numerical simulation results with the field measured data to verify thecorrectness of the model. At the same time based on this project aiming at theexcavation process of foundation pit pile diameter and excavation depth offoundation pit the influence of existing subway station structure and surrounding soilis analyzed. Four excavation procedures five different pile diameter (0.5R~1.5R) andfive different excavation depth (0.5H~2.5H) are set up respectively.And the verticaldisplacement of adjacent subway station structure and the deep layer of retaining pileare excavated under different working conditions. By paring the horizontaldisplacement with the vertical displacement of the surrounding surface the influencelaw of the change of the excavation depth of foundation pit on the surroundingenvironment under the same retaining pile diameter and the same supporting schemeis obtained which provides a reference for similar projects. The main conclusions areas follows:
(1) Through the analysis of the influence of foundation pit excavation on thenearby metro station it can be seen that with the excavation of foundation pit thestructure of metro station will rise and increase with the excavation especially whenthe excavation is near the side of the station the horizontal displacement and verticaldisplacement will increase.
(2) Different excavation processes have different impacts on the nearby metro