| Based on the former study, the coupled action of retaining structure, soil and buried pipelines is considered in this paper,examined by 3D finite element, use numerical simulation method to study the spatial deformation of buried pipelines systematically. The main content of this thesis is as follows:(1)3D finite element model with pipeline, soil and retaining structure is founded. Soil is analyzed by using solid element, non-conforming element to retaining structure, and the pipe is simulated by shell element. Contact surface simulation to the interaction of soil-retaining structure &buried pipelines, terreneness layer stratifying process to soil, take stepped excavation into account.The model in this paper can accord with the actual case.(2)Under different occasions after excavation, the regulation of surface deformation around the pit and strata lose is studied by the finite element model in this paper.(3)The pipeline nearby cantilever foundation pit is studied by the finite element model in this paper. Several factors such as pipe material, buried depth of buried pipelines, distance form excavation, the outside diameter and wall thickness of pipelines, the elastic modulus of pipe to that of soil, etc.are analyzed.(4)The pipeline nearby the north braced foundation pit in Wuhan Changjiang tunnel is studied by the finite element model in this thesis. And the disciplines of pipeline affected by stepped excavation, pipe material, buried depth, distance form excavation, the outside diameter and wall thickness of pipelines, the elastic modulus of pipe to that of soil, and the pipelines nearby itself.(5)Finally, the north pit in Changjiang tunnel project is analyzed by the 3D FEM. The theoretical results will be smaller than the real values due to the limitation of simulation model and the effect of underground water. But the results and regulations can demonstrate that the Finite Element method can predict the safety of buried pipelines, and guide the construction.
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