The Finite Element Modelling On Anti-inrushing Of Deep Foundation

In recent years, with the development of urban construction, excavation engineering have proliferated and the excavation of the foundation pit is much deeper. It makes the scale of excavation engineering be much larger,and also brings more problems about the stability of foundation pit.According to the research, the important factor of stability is the groundwater. It is one of the direct cause of foundation stability in coastal areas vigorously. The confined aquifer under the basement will be easy to cause inrush, basement uplift, piping or the flow of sand and other engineering accident in the excavation of foundation.This paper studies the influence of confined groundwater on the bottom of deep foundation and the surrounding, simulates and analyzes the inrush of foundation pit and the influence of seepage flow by using Plaxis.Using the soft soil creep model to simulate the soil as the actual works in coastal areas,because the chief soil is clay in that areas. Author tested and verified the soft soil creep model through the full size field test to ensure the simulation consistents with the actual situation. Because the pressure balance method in current design manual does not take the shear strength of soil into account, author used the homogeneous continuum method instead of the pressure balance method in the simulation on the anti-inrushing stability of deep foundation pit. According to the simulation of seepage flow, the permeability coefficient which calculated based on the principle of effective stress is more close to the actual situation when the groundwater exists in soil layer. According to the simulation and analysis of the actual project,the excavation pit and dewatering has great impact on foundation and its surrounding. Dewatering can improve the indicators of physical and mechanical properties of soil and increase the effective stress of soil.While it also lead to additional settlement of the soil at the bottom of the pit...