【作者】 周正永；

【导师】 胡长明；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2010， 硕士

【摘要】 本文在总结目前软土地区深基坑工程研究现状及现有研究的基础上,以深圳海积软土地区某地铁车站深基坑工程为背景,通过现场监测、室内土工试验等手段,结合理论分析及有限元数值模拟的方法对软土地区深基坑工程稳定性、工程降水对基坑周边环境的影响等进行了一系列的探讨,为今后类似工程的施工指出了一些实用的工程措施。本文的主要工作及相关结论如下所述：(1)本项目的研究重点是以重塑软土作为研究对象进行一系列的室内试验,主要包括三轴压缩试验、一维固结试验等,从而探讨不同排水条件、固结方式下土体的变形特性,并通过一系列的分析,得到：多种因素会影响海积软土的变形特点性质,例如土体排水条件、初始固结度、荷载比等；土体的先期固结压力和试验中的荷载比决定固结压力与次固结系数的关系。(2)针对基坑工程的时间效应问题,利用有限元软件建立以软土弹塑性模型为基础的考虑基坑工程分步开挖模型,讨论模型参数对围护结构的变形与内力、土体变形的影响,得到如下结论：土体的固结程度对于基坑开挖的影响非常大,随着土体固结程度的不断提高,周边土体的沉降有一定的降低,围护墙的变形亦有一定的降低。(3)利用有限元软件对基坑开挖过程中土体中的承压水渗流特性进行了分析,充分了解软土基坑开挖过程中地下水的流动,并且以渗流理论、随机介质理论和粘弹性理论为基础,导出了考虑渗流作用的基坑降水地表沉降计算公式,并且最后运用数学叠加原理,得到由开挖和降水引起的最终地表沉降分布计算公式。(4)在现有软土变形理论的基础上,根据现场实测数据以及相关有限元计算分析了围护结构变形与时间的关系,从而制订了在海积软土地层深基坑施工的开挖过程中的变形控制要点。在严格按照相关规或范标准进行设计和施工、准确理解基坑变形原理和各种影响因素的前提下,深基坑工程的经济性和安全性完全能够得到保证。更多还原

【Abstract】 This article summarizes the current existing research on the soft soil deep foundation engineering, baseing on some Shenzhen marine soft soil areas subway station engineering,through indoor soil test and insite monitoring, combining with theoretical analysis and finite element numerical simulation methods,we discussed the stability, the effects on precipitation of foundation engineering, indicated some practical engineering measures for future similar works. The main jobs and conclusions are as follows:(1)Based on a series of laboratory tests with reshaped soft soil,including one dimensional compression test,triaxial compression test,deformation characteristics of soft siol on different drainage condition.Through a seris of analysis,indicated:there were many factors impacting on the deformation characteristics of soft siol,such as the initial consolidtation, drainage condition, load ratios and so on;the ralaionship between coefficient of secondary consolidation and consolidation pressure depended on preconsolidation and load ratio in the test.(2)Aimed at the time effect of the deep foundation,using the finite element software,the calculated model were estabished.The effect of the model parameter on the deformation of the soil and deformation and stress of the retaining structure,indicated:the effect of the consolidtation of the soil on the deep foundation is great,as the siol consolidtation increasing,the soil subsidence reduced, deformation of the retaining structure also reduced some.(3)Confined water in the project of the exvacating deep foundation and see the flow of the underground water.Also based on the stochastic medium theory, seepage theory and visco-elasticity theory, a new calculation method which taKing the seepage into account was concluded, combining with the adding theory,this paper educed the distributed formula for the surface subsidence.(4)Based on the actual the soil defotmation theory,we analysis the relationship of defotmation of the retaining structure and time based on the insite measured data and result of the finited element calculated, the sequence of digging and controlled point in the deep foundation project in the marine soft soil areas were formulated accordingly.Understanding the theory of the foundation deformation and influenced factors rightly, design and construct according to correlated standard and criterion strictly, security and economy of the deep foundation could be guaranted entirety.更多还原