Research On The Ground Settlement Induced By Shield Tunnel

Ground settlement and soil movement induced by tunnel excavation inmetropolises will have negative influence on surrounding buildings, which attractsmany attention to the ground settlement and soil movement research in undergroundengineering. Combined site settlement monitoring and numerical model used FLAC3D,factors affecting the ground settlement and soil movement are analysed.The maincontent of the thesis is as follows: In order to study how the extent of all the factors influnced on ground settlementand select the best tunnel excavation project, the Orthgonal test is used to design themodelling projects, based on the resonable factor level selection.Then,parametersrelated to the ground settlement are studied with the variance analysis method andconclusions are made about the factors' influence on these parameters. According to the selected 32 experimental projects, full process of tunnelexcavation is modeled based on the special geothechnical software FLAC3D andassisted by the inside language Fish. The characteristic of ground tranverse settlement and lognitudinal settlement aresummed up, based on the combination of site survey data and the modellingresult.Soil stress field variety and displacement field variety are also described in thisthesis.The following conclusions can be drawn as follows: 1 The soil stress field and the displacement field monitored in-site is in goodagreement with the results by FLAC3D. 2 Both stress and displacement near the excavation are more influnced by tunnelexcavation than that on the surface ground. 3 According to the variance analysis of factors affecting the maximum surfacesettlement, the tunnel diameter, tunnel buried depth, soil frictional angle are the mostimportant factors; the lateral pressure coefficient, advance per step, soil cohesion however haveless influence. 4 Based on the variance analysis of factors affecting the surface settlement troughparameter i, the tunnel diameter, tunnel buried depth, soil frictional angle, the lateral pressurecoefficient are dominant factors, whereas advance per step and soil cohesion are secondary.