【作者】 李新军；

【导师】 喻勇；

【作者基本信息】 西南交通大学 ， 固体力学， 2010， 硕士

【摘要】 武汉地区深基坑事故中,九成以上是因为地下水控制失效造成的。其中,承压水含水层在长江一级阶地中普遍存在,且含水层厚度很大,承压水头很高,成为武汉地区深基坑工程的一大特点。针对武汉长江一级阶地地铁深基坑,研究其降水与开挖施工过程中引起的地面沉降以及基坑稳定等影响与变化规律具有重要的现实意义。(1)基于地下水渗流计算与三维比奥固结理论,对深基坑降水与开挖的流固耦合效应进行了分析,建立了渗流场与应力场耦合计算模型。并对三维快速拉格朗日有限差分程序FLAC3D的流固耦合计算模式进行了研究。(2)对武汉长江一级阶地地下水埋藏类型与其对深基坑危害特点作了总结与分析,重点研究了武汉长江一级阶地的承压水特征。利用FLAC3D对某竖井基坑施工过程进行了数值模拟,计算结果与监测结果吻合较好,验证了FLAC3D流固耦合模型和编程思路的合理性与正确性。(3)最后针对处于长江一级阶地的武汉市地铁四号线一期工程工业路车站,使用FLAC3D对其降水与开挖施工过程进行了渗流应力耦合模拟,分别对各种工况条件下的地表沉降、孔隙水压力特征、坑底隆起、动水压力等计算结果进行了研究,并对地下连续墙深度、承压水位变化影响、耦合与不耦合等情况进行了对比与分析。通过对上述计算结果进行研究与分析,获得了一些有意义的规律。其中,地表沉降形成了二次函数曲线分布形态的沉降凹槽,降水引起的沉降要比开挖引起的大；武汉长江一级阶地承压水水头高,在施工过程中坑底向上回弹隆起较大；地下连续墙以下渗流速度最大,容易发生渗透破坏,随着挡墙高度的增加,渗流路径加长,会导致水头损失的增加,渗流速度减小；武汉长江一级阶地承压水与江水有密切的水力联系,承压水头越高,降水引起的地表沉降越大；相较于不考虑流固耦合计算,考虑耦合的计算结果与工程实际规律更为吻合,能起到更好的预测与信息化施工论文成果在一定程度上弥补了对武汉长江一级阶地地貌条件下渗流场与地下水控制研究的不足。为该基坑施工过程中的防水止水与加固设计提供了理论依据,有益于信息化施工；并为今后类似的工程设计与施工提供了参考与借鉴。更多还原

【Abstract】 One reason for 90% deep foundation pit incidents in Wuhan, was failure of controlling underground water. Among them, confined water aquifer is very common in the First Yangtze River’s terrace, the aquifer is thick, and the water head is high, which is very typical in deep foundation ditch project of Wuhan. Therefore, studying on change law of land subsidence and foundation stability caused by precipitation and excavation is of important practical significance.The major works are as follows:(1) Based on groundwater seepage calculation and three dimensional Biot consolidation theory, fluid-solid coupling effect of precipitation and excavation about deep foundation pit is analyzed. Seepage field and stress field coupling calculation model is established. And the fluid-solid coupling calculation model by using FLAC3D was studied. (2) Groundwater type and disaster of First Yangtze River’s terrace in Wuhan foundation are summarized and analyzed, and the confined water are studied mainly. Then the construction process of a shaft excavation are simulated by using FLAC3D, The numerical simulation results show good agreement with the monitoring data, which verify rationality of the FLAC3D fluid-solid coupling model and the programming ideas. (3) Finally, seepage-stress coupling simulation of Gongye station’s precipitation and excavation is carried out with FLAC3D, and all the results of settlement, pore pressure, swell of pit bottom, hydrodynamic pressure are stydied. Then the affect of changes in diaphragm wall depth, confined water level, coupling or no coupling are compared.The results show that, Surface subsidence show a settlement groove of quadratic function curve, causing precipitation than the settlement due to excavation of a large; confined water head is high at Wuhan First Yangtze River’s terrace, swell of pit bottom is large; Seepage velocity is largest under the diaphragm wall, prone to infiltration and sabotage, as the wall height increases, longer flow paths, will lead to increased head loss and flow rate decreases; Confined water of Wuhan First Yangtze River’s terrace is closely associated with the river, confined water head is higher, surface subsidence is larger; Compared to no coupling, coupling the results considering the actual rule is more consistent with the project, can play a better prediction and information for construction. This paper makes up for preliminary study on seepage and groundwater control of Wuhan First Yangtze River’s terrace. It provides a theoretical basis for waterproof and reinforcement design in foundation construction process, and it provides an experience and reference for design and construction of similar projects in future.更多还原