Centrifuge Model Test Investigation Of Underwater Slurry Shield Tunnel Face Stability

The large cross-section tunnels under rivers or seas play an important role in promoting sustainable development of economy and society.Due to the high water condition,the maintenance of tunnel face stability is difficult.Based on practical issues,this study focuses on the face stability analysis of underwater shield tunnel in sandy soils.Centrifuge model test and numerical investigations were conducted to study the failure mode of tunnel face collapse.He major works and main results of this dissertation are as follows:(1)Designed an equipment system in a geotechnical centrifuge to study the face stability of slurry shield tunnel under the condition of seepage flow,which considering the slurry membrane under high water pressure,the simulation of the failure process of the excavation surface of the shield tunnel is carried out under the condition of high water pressure(0.9MPa and 1.2MPa)and seepage flow.(2)Monitored the soil internal stress and deformation under high water pressure(0.9MPa and 1.2MPa)during the construction via miniature earth pressure transducer.(3)The Particle image velocimetry(PIV)method was adopted to analyze the soil deformation in vertical plane and the progressive failure pattern was proposed.(4)A three-dimensional fast Lagrangian differential finite element method is used to simulate the deformation and failure of excavation face considering the seepage effect under high water pressure.The limited face pressure of tunnel face is obtained by a great deal of analysis,and the influence of tunnel depth,the depth of ground level?...