The Impact And Numerical Simulation And Analysis On Unsteady Seepage In The Execution Of Foundation Pit Engineering

Foundation pit engineering is one of the old and complicated subjects, in which groundwater seepage is the hardest one. At present time, most accidents of foundation pit engineering are related to groundwater seepage. The research on groundwater seepage in foundation pit engineering is insufficient by far. In present foundation pit design, seepage function is not considered basically. If it is considered, it is still steady seepage in most conditions. There are few researches on unsteady seepage in foundation pit engineering.This paper emphasis researches on the function of unsteady seepage in the process of the foundation pit excavation. In this paper , not only deduce the basic differential equation about unsteady seepage, but also introduce the Van Genuchten model (VG model in short )which is suitable for steady, transient and (un)saturated groundwater seepage analysis. According to this model the saturation depending on effective pressure head, thus it provides the convenient condition to study the impact of the unsteady seepage in foundation pit engineering for us.The paper adopts complicated soil constructive model-Hardening soil model, which is good at dealing with loading-unloading problems, to study the deformation and stability in the excavation process of the foundation pit combined with unsteady seepage model.Through the numerical simulation of the practical project, contrasting the differences of the pore pressure and effective stress in soil, displacement,moment of flexure and shear force, sedimentation of ground surface and heave of the bottom of the foundation pit in unsteady seepage conditions and steady conditions. According to the research, the deformation of the foundation pit and support structure is smaller and the foundation pit is more stable. In response to all the researches, it can supervise the practice better and make the optimum design in foundation pit engineering. In addition, it can reduce unnecessary waste and reduce the cost of the whole project. In brief, it is necessary to study the unsteady seepage.