Stability Analysis Of Foundation Pit Considering The Effect Of Seepage Flow

Foundation Pit is a special temporary slope. The theories of stability analysis of Foundation Pit stemmed from those of slope and developed with them. Among the various factors that affect the safety of slope, seepage flow is the most difficult one to determine. Several simplified methods, including the common used methods such as hydrostatic pressure method and replaced weight method, were developed on the basis of many years' experience in slope stability analysis. The instalment of seepage-control equipment in the construction of Foundation Pit will make the distribution of seepage pressure much different from what the simplified methods had supposed. In this situation, using the simplified methods to determine the effect of seepage flow will lead to inaccurate even incorrect results. To avoid the great losses arising from the disastrous collapse of Foundation Pit due to the inappropriate treatment of underground water, a fit theory for the stability analysis of Foundation Pit with seepage flow must be developed.In this dissertation, a new model for stability analysis of Foundation Pit with seepage flow was developed by studying the seepage flow field around Foundation Pit and the theories of stability analysis of slope. numerical model simulating the seepage flow field with complicate boundary conditions was proposed according to the theory of steady state flow and the actual boundaries of Foundation Pit.According to the actual measures of seepage control, seepage flow within confined boundaries and that with free water surface were classified. The latter was computed by Dummy Element Method, which united the merits of fixed mesh method and changing mesh method.To simulate the boundary conditions, the models of using ditch to simulate large-diameter well, same node with different numbers method to simulate small-diameter well and baffle-wall were put forwarded.?A new model for stability analysis of Foundation Pit, which integrated FEM and the method of slices, was developed. This model not only could bring the efficiency and accuracy of FEM into full play but also could utilize the rich experience in using the method of slices.?Adding Pro- and Post-processing functions, including auto element-partition and data conversion, to the core program improved its application.?In analyzing a Foundation Pit with baffle-wall, several methods were compared and the evaluation of their applicability was useful in engineering design..?The new model also was used to analyze one deep Foundation Pit involving pumping.?The new model developed in this dissertation blazed a new path for stability analysis of Foundation Pit.