Finite Element Analysis Of Deformation Of Nearby Underground Pipelines Affected By Deep Excavation

Research on nearby underground pipelines affected by deep excavation is an important project in foundation pits. Based on the former study, the coupled action of retaining structure, soil and pipeline is considered in the paper. The project is analyzed by 3D finite element with finite element soft ANSYS. The main content of study is as follows:(1) The specialties of all kinds of finite element theory are introduced. The key techniques and element types of 3D finite element model to analyze the project are stated especially.(2) 3D finite element model with pipeline, soil and retaining structure is founded by general finite element soft ANSYS. Soil is analyzed by using block element SOLID45. Both the pipeline and the diaphragm are simulated by shell element SHELL63 of four nodes. Friction element of no thickness is adopted to simulate the interaction of soil-retaining structure. Soil is dealt with layered in term of soil type, and stepped excavation is considered.(3) The factors that excavation of two kinds of foundation pits, cantilever foundation pit and braced foundation pit, impact deformation of underground pipeline are analyzed by finite element model in the paper. Firstly, the pipeline in the cantilever foundation pit is analyzed. Several factors such as distance from excavation, buried depth, pipe material, substratum type, soil type around the pipeline, dimension of foundation pit etc. are studied especially. Secondly, that deformation of underground pipeline is affected by excavation of braced foundation pit is analyzed. Some factors such as stepped excavation, distance from excavation, buried depth, supporting stiffness are considered especially.(4) The deformation of underground pipeline is compared with the deformation of soil under the circumstance of no pipeline in the same place around foundation pit by ANSYS. They are compared under the circumstances of different distance from foundation pit, different depth and different pipe material. The conclusion is that the shape of deformation curve of underground pipeline accords with that of soil under the circumstance of no pipeline in the same place.(5) Finally the engineering example is analyzed by 3D finite element. The deformation of underground pipeline is calculated. It shows that good agreement between the theoretical results and observeing results attests to the validity of the mothd.