Creep And Concurrent Deformation Analysis Of Deep Excavations In Soft Clay

Based on elastic foundation beam method, three-dimensional finite element analysis is used for foundation excavation. However, analysis results are influenced by limitations of elastic foundation beam method, rheological effects, plastic behavior of soft soil can't be considered. Moreover, the coefficients of subgrade reaction are often determined by empirical analysis, which influences the security and economy of foundation engineering.To discuss the rheological effects of soft soil, shear strength is divided for rheological analysis. Viscosity coefficient of remolding soil is used to modify partial parameters of routine soil mechanic tests. So the shear strength caused by rheological effects can be considered.Based on shear stress-strain relation of soft soil, an approximate solution to the coefficient of subgrade reaction in elastic stage is proposed. To discuss the plastic behavior, the shear stress is divided to simplify the judgment of elastic and plastic stage. Then the judging method is proposed, and the proposed method can consider the stress history and viscosity shear strength of soft soil.In this paper, a FEM program DPFBM1.0 (Double Plastic Foundation Beam Method (Version 1.0)) is established. With this program, the influence of some parameters on foundation excavation is fully studied, the parameters include: compression modulus, cohesive strength, angle of internal ficiction, effective angle of internal friction, the embedded length of the wall and building load.To verify the program, a foundation excavation case is analyzed respectively by DPFBM1.0 and elastic foundation beam method. Some conclusions are obtained: consolidated quick shear test is appropriate for excavation completion stage, and triaxial consolidated undrained test is for short-term excavation.