Deformation Of Foundation Pit Considering Coupled Effects Of Seepage And Stress

During the excavation of deep foundation pit, because great groundwater lowering is needed, the hydraulic head difference will result in drastic flow of the ground water in the neighborhood area of deep excavation, which will influent the deformation of foundation pit and bring about environmental problems that can't be ignored. In order to accurately analyze the deformational laws of foundation pit resulted by deep excavation and drainage, seepage force produced by water flow through soil should be paid great attention. The deformation of foundation pit reflects the interaction between groundwater seepage and excavation stress. Aiming at this problem, the following contents are studied in details in the thesis:(1) By means of eight nodal equal element, the finite element coupling equations of three dimensional unsteady seepage and stress are deduced by using Galerkin's finite element methods with three-dimensional unsteady seepage continuity equation and stress equilibrium equations.(2) Several questions of applying the software (ABAQUS) in simulating foundation pit engineering are studied, such as iterative method, constitutive model of soil mass, numerical ways of determining initial geo-stress, additional loads, simulation of inner supporting and pre-axial force, analysis of contact surface and so on.(3) A simple and practical method for simulating drainage wells is introduced, which is called as "using fissure instead of lined drainage wells and adjusting the flow". A simple example is applied to validate the feasibility of the method.(4) Taking the excavation project of the Zhujiang Road station of the No.1 line subway in Nanjing for an example, deformation distribution of the foundation pit in the process of excavation and drainage is studied by coupling analysis of unsteady seepage and stress, and the deformation laws of every load step can be obtained.(5) Influences of no drainage wells or no ground superimposed load or reinforcement way using continuous concrete wall instead of SMW wall on foundation pit deformation are also studied in the thesis.