Numerical Analysis Of Stability Of Retaining Wall In Deep Excavation Of The Subway Station

With the continuous development of the city, more and more large and public facilitiessuch as high-rise buildings and subway station emerge. As the underground space isdeveloped in big and medium city, the number of foundation pit projects grows gradually.According to the surroundings, the requirements on foundation pit construction getting higheras the foundation pit becomes deeper and neighborhood buildings grow closer. In the processof the deep foundation pit construction, pit excavation stability becomes an increasingconcern. Not only the safety of the neighborhood buildings should be ensured, but the securityof drainage pipeline, cable, gas piping and transport system should be ensured. Retainingsystem stability is the important part of the pit excavation stability.Firstly, the method to simulate the foundation pit excavation is expounded in this paper.Some problems are engaged in the simulation of the excavation progress including theinteraction between the wall and soil, two-dimensional joint element, constitutive model,gravity stress, preloading, the simulation of the excavation and etc. Based on QingDaoXiliuzhuang subway station excavation, conceptual design and study on building retainingsystem are obtained according to design specifications and analysis of excavation process iscarried on by use of MIDAS/GTS.Secondly, based on QingDao Xiliuzhuang subway station project, research on thecommon strut steel pile strut is carried on. According to the stability analysis results of the pitwith different layer of strut, the rule of force changing is achieved and the optimized layer ofstrut is obtained.In the process of foundation pit excavation, the stability of the retaining system is acomplex problem with complex factors. At last, based on QingDao XiLiuZhuang subwaystation project, by use of MIDAS/GTS, research on factors like strut stiffness, strut horizontal spacing, the magnitude of the preloading, entering ground depth and soil condition areconducted and some reasonable values are obtained from the results of comparison andanalysis. The optimization mathematics model of QingDao XiLiuZhuang subway stationexcavation is adopted considering the pit stability and cost.The proper layer of strut, proper strut stiffness, proper strut horizontal spacing andmagnitude of preloading are given out in the thesis can provide some experience to the designan construction of the pit excavation.