Pseudo-static Analysis On Rectangular Underground Tunnel Under Earthquake Loading

As an important component of urban transportation engineering, the study onseismic properties of underground tunnels is an important part in earthquakeengineering and disaster prevention engineering due to earthquake in urban areas.However, limited studies have performed in this area in China, therefore, so far, nointact design specification for anti-earthquake design for the structures ofunderground tunnels is available. If the structure of the underground tunnel isdamaged in an earthquake, it is hard to rescue the human life during the disaster,meanwhile, it is also difficult to restore the structures after the earthquake. Theinteraction between soil and structure during the earthquake could change thedynamic parameters in terms of ground response in the soft site, hence, influencingthe seismic performances of the structures of the buildings on or beneath the ground.Therefore, the study on subway structures in terms of anti-earthquake design is ofgreat engineering importance.The ABAQUS model for pseudo-static analysis on interaction between soil andstructure is established to validate the Huo’s solution in linear elastic range, afterthat, the results from the numerical analysis based on the ABAQUS model arecompared with the analytical results from the Huo’s solution. Based on thepseudo-static analysis is also established to validate the Huo’s solution in nonlinearrange. Correspondently, the numerical results are also compared with those from theHuo’s solution in the nonlinear range. Based on the analysis in terms of theinfluencing factors on the displacement of the underground tunnel, the computationcode for normalized displacement ratio is developed.The numerical simulation model is used to simulate the performances for therectangular structure with three different aspect rations in the sheared, far andinfinite elastic field. Comparative analysis of the pseudo-static method, the dynamicresponse analysis and Huo method nonlinear elastic part of the analytical solutionamong the results contemplated Hence pseudo-static analysis results than thedynamic response results closer Huo method the results of the analytical solution. Inaddition, to be compared the error between the pseudo-static method and thedynamic response of law in less than10%, can be seen pseudo-static method thereis a greater superiority and dynamic analysis of underground structures in different soil under earthquake the displacement of a large number of estimates provide areference basis for the actual project.The influencing factors to normalized displacement ratio are chosen as thedepth of the underground structure, the friction coefficient at the interface betweensoil and structure, the ratio between the stiffness of the structure and the soil, andthe aspect ratio for the rectangular. A computational program to calculate thenormalized displacement ratio is coded in MATLAB. The computational programcan calculate the normalized displacement ratio at arbitrary combinations among theinfluencing factors, which are given different ranges, i.e., the depth of the structureranges from2m to17m, the relative stiffness ratio:0.498to0.996, the aspect ratiofrom1to3and the friction coefficient from0.4to0.8.