Study On Responses Of Buried Pipeline To Shield Tunneling

Tunneling will inevitably result in a loss of ground causing soil deformation. The tunneling-induced soil deformation may do damage to the underground utilities. It is necessary to predict the movements of the ground surface movements and their influence on the adjacent pipeline so that effective measures can be taken to protect these utilities. Winkler's elastic beam model is carried out in according to the characteristics of underground utility. FLAC^3D is used to research into the influences of the tunneling on the underground utility. The major research in this study is as follows:Based on the elastic theory of Winkler's beam, the equations for displacements, rotation, bending moment, and shear force are established. Secondly, based on the proposed theories by author, a case history is analyzed. The factors such as the diffusion angle of the subgrade, and buried depth of the underground pipeline are investigated. displacements of underground pipeline, rotation of underground pipeline, bending moment of underground pipeline, and shear force of underground pipeline are established using theoretical method, which are programmed using the code MATLAB.Influences of the tunneling on underground utility are studied by using the code FLAC^3D. Factors such as variety method of excavation , different radius of the pipeline, the different distance between the pipeline and the tunnel and multiple tunnel's excavation are taken into consideration. major factors are taken into consideration. The conclusion are drawn as follows: the horizontal displacement of the pipeline can be ignored. The vertical displacement of pipeline is related to stiffness of the pipeline, the displacement between the pipeline and the tunnel. The effect on the pipeline caused by the two tunnels' excavation equals to the effect of separate tunnel's excavation.Meanwhile, the methods to assess the pipelines safety conditions are summarized in this thesis. When knowing the pipelines material, vertical displacement of pipeline, rotation and stress can be calculated, through that we can assess the pipeline safety condition. the thesis also put the method forward to assess distortion of pipelines before excavation, that can be used to make primary assessment.