| Public hazard of city construction in China soil excavation impact on the surrounding environment, such as the deep soft clay generally exist in Guangzhou and other coastal areas or along River, the new (expanded) construction of a road or railway, the excavation of foundation pit, industrial and civil building foundation treatment, usually encounter excavation soil large deformation and impact the original structure of the deep excavation. With the acceleration of Guangzhou rail transit and underground space construction, it set a higher request to the safety and design of underground engineering. Based on the analysis of the related data of large deformation and the results of previous studies, the plane beam element Updated Lagrangian (U.L.)and Total Lagrangian(T.L.) expressions were derived, and the use of large-scale finite element software ABAQUS on the pile supporting structure of large deformation finite element analysis. The main contents of this paper include:(1) Introduced the distribution and engineering characteristics of soft soil in Guangzhou area, physical, mechanical properties of summary indicators of soft clay in Guangzhou area, and provide reference and control parameters for the model selection in numerical simulation ABAQUS.(2) Introduced the finite element matrix expressions of the U.L. and T.L. support rod element theory, U.L. analysis on foundation pit deformation under Biot consolidation theory and Pile-strut bracing structure, finally it deduces the pile as the finite element matrix expressions of plane beam element U.L. and T.L. description.(3) Introduced the ABAQUS software and its application in geotechnical engineering, briefly discusses the elastic model (linear elastic model, porous elastic model, Duncan Chang model) and the platstic model (morh-coloumb,the critical state plasticity model)adaptation scope and conditions, and to analyze the excavation engineering by using the constitutive model of deformation characteristics and differences in size analysis.(4) the large deformation simplified3D model of the analysis results with the typical plane strain model calculation results were compared, using a simplified three-dimensional model to verify reliability analysis. Using the simplified three-dimensional model of a foundation pit example for large deformation analysis of considering the effect of seepage flow, mainly analyses the pile supporting foundation pit during the excavation of the displacement field distribution, the distribution of pore pressure and retaining pile bending moment of change, the time effect of pile supporting in pit excavation, the final analysis no effect of seepage and supporting material type on the pile supporting foundation pit, soil permeability coefficient of the soil.(5)Using large deformation analysis of considering the effect of seepage flow for an engineering example, and compared with small deformation analysis, trend of the calculated results of two kinds of analysis with actual engineering monitoring values coincide, but considering the large deformation analysis of seepage results are relative to the small deformation analysis is more in line with the actual engineering.Finally, summed up research results, some conclusions, then put forward its own deficiencies and problems in the course of the study, and pointed out the problems and prospect in further research. |
PDF Full Text Request