防渗水基坑支护结构设计及性能试验研究

发布时间：2018-03-15 20:41

本文选题：基坑开挖　切入点：地下水　出处：《南昌航空大学》2017年硕士论文　论文类型：学位论文

【摘要】：在高地下水位地区进行基坑开挖时,为降低地下水位对基坑稳定性的影响,常需进行基坑降水施工,由于基坑降水会诱发土体的固结变形,进而对临近建筑物的安全状态产生不利的影响。对此,本文设计了一种防渗水基坑支护结构,通过室内试验和仿真分析相结合的方法,对设计结构性能及影响因素进行分析,主要得到以下研究成果:(1)针对基坑降水诱发土体变形问题,本文设计了一种防渗水基坑支护结构,该结构在基坑侧壁设置竖向截水层,在基坑底部设置坑底截水层,形成三维密封的防渗体系,从结构特点及受力机理来看,该结构可以有效的阻断地下水的渗透路径,减小基坑外侧土体的变形。(2)根据所提出的防渗水基坑支护结构,开展室内模型试验,对基坑外不排水开挖和基坑外排水开挖两种工况下,土体变形、支护结构变形和支护结构应力进行测试,从测试结果来看,两种工况下土体位移、支护结构位移与支护结构的应力存在一定的差异。从影响幅度来看,基坑外不排水开挖相对于基坑外排水开挖,土体竖向位移减小了约50%;土体水平位移减小了约20.3%;支护结构的位移增大了约20%;支护结构的应力增大了约25%。(3)根据设计结构性能仿真分析结果,发现各因素改变都会对支护结构性能和周边土体变形产生影响。从对支护结构性能影响来看,支护结构高度和支护结构刚度对支护结构性能影响较大,水头差和墙背土性对支护结构性能影响较小。从对基坑周边土体变形影响来看,水头差对土体变形影响较大,支护结构高度和支护结构刚度对土体变形影响较小。
[Abstract]:In order to reduce the influence of groundwater level on the stability of foundation pit during excavation in high groundwater level area, it is often necessary to carry out foundation pit dewatering construction, because foundation pit dewatering will induce consolidation deformation of soil. In this paper, a kind of seepage proof foundation pit supporting structure is designed. Through the combination of indoor test and simulation analysis, the performance of the design structure and its influencing factors are analyzed. In order to solve the problem of soil deformation induced by dewatering of foundation pit, this paper designs a kind of impervious foundation pit supporting structure. The structure has vertical water intercepting layer on the side wall of foundation pit, and bottom water intercepting layer on the bottom of foundation pit. According to the structure characteristics and mechanical mechanism, the structure can effectively block the seepage path of groundwater and reduce the deformation of soil outside the foundation pit. The indoor model test was carried out to test the soil deformation, support structure deformation and support structure stress under the two conditions of undrained excavation outside the foundation pit and drainage excavation outside the foundation pit. From the test results, the displacement of the soil under the two working conditions was analyzed. There are some differences between displacement of supporting structure and stress of supporting structure. In terms of influence range, undrained excavation outside foundation pit is relative to drainage excavation outside foundation pit. The vertical displacement of the soil is reduced by about 50 percent; the horizontal displacement of the soil is reduced by about 20.3; the displacement of the supporting structure is increased by about 20; the stress of the supporting structure is increased by about 25.3; It is found that the change of various factors will affect the performance of the supporting structure and the deformation of surrounding soil, and the height of the supporting structure and the stiffness of the supporting structure will have a great effect on the performance of the supporting structure. The difference of water head and the soil property of the back of the wall have little influence on the performance of the supporting structure. From the effect on the deformation of the soil around the foundation pit, the difference of the water head has a great influence on the deformation of the soil, and the height of the supporting structure and the stiffness of the supporting structure have little effect on the deformation of the soil.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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