Numerical Simulation Of Foundation Pit Excavation Considering Seepage

In the construction of high-rise buildings and underground projects, it is inevitable to encounter the problem of deep foundation pit excavation. If the control measure fail, pit excavation will induce large deformation of deep foundation pit and affect security and function of the surrounding structures seriously, such as urban road, pipeline, high-rising building and so on. So it is very important to study the deformation mechanism of foundation pit, the influencing factors of deformation of deep foundation pit, the influence of the deep foundation pits on the surrounding environment.In the thesis, based on the worldwide research achievements, the finite-element model was established according to the behavior of deep foundation pit excavation. The deformation mechanism of foundation pit, the effect of seepage flow to foundation pit, the influencing factors of deformation of deep foundation pit considering seepage were simulated and analyzed. The main achievements are as follows:Firstly, based on the foundation pit of Jinshazhou Subway, the whole excavation process of the pit wss analyzed by the finite element program ABAQUS. With the computation results, the variation laws in constructing of the foundation pit, such as the deformation of foundation pit, surface settlement, the basal heave and the strut axial forces, were concluded.Secondly, with the help of the finite element program PLAXIS and taking the foundation pits of Tianjin Subway Line One as an example, variation laws of foundation pits deformation were concluded under the conditions of seepage, no seepage and hydrostatic. Meanwhile distribution laws of seepage caused by every phase of dewatering were deduced. The influence law of deformation of foundation pit caused by seepage resulted from foundation pit dewatering was gained from the computation results.Finally, considering the seepage, the influencing factors of deformation were discussed in the numerical simulation by PLAXIS finite element program, including design parameters of supporting walls and strut, natural environment, ground overload and so on. The laws of the influencing factors for deformation of foundation pit were concluded. Some useful controlling measures and methods of deformation of foundation pit were obtained from the results, which can provide guidance for design theory and construction methods in similar projects.