[Objective]Solve the problem of excavation sur-face stability during shield tunneling with pressure entry in shallow-buried sandy stratum.To solve the problem of the sta-bility of tunnel face of shield tunnel with pressure into the chamber in shallow buried sandy soil stratum.[Method]The limit support pressure during the shield tunneling pressurized chamber entry operation is studied by combining numerical simulation,theoretical analysis and engineering verification methods.Firstly,the active failure phenomenon of shallow-buried sandy soil stratum is studied by numerical simulation,and the corresponding limit support pressure and failure zone shape are obtained.Then,based on the numerical simulation results,the failure mode applicable to shallow-buried sandy soil stratum is constructed,and the corresponding ultimate sup-port pressure is solved.Finally,the model is applied in the Hangzhou Metro Line 5 pressurized inlet project,and the ground settlement is monitored.[Result & Conclusion]The limit support pressure increases approximately linearly with the increase of burial depth,and decreases approximately exponen-tially with the increase of internal friction angle;the instability mode of the shallow-buried stratum presents the shape of lower wedge and upper inverted cone/platform,in which the upper failure zone is further split into the damage core zone and dis-turbance zone.By comparing with the numerical model and the literature model,it is found that the proposed wedge+invert-ed cone/platform model can better describe the phenomenon that the damage zone can reach the ground surface due to the inability of the shallow-buried sandy stratum to form an arch;during the shield pressure entry construction of Hangzhou Met-ro Line 5 project,the maximum ground settlement value caused is 9.5 mm,and the influence range is within 10 m on both sides of the tunnel axis.
关键词
地铁/浅埋隧道/砂土地层/盾构/带压进舱/开挖面稳定性/极限平衡法
Key words
metro/shallow-buried tunnel/sandy soil stra-tum/shield/excavation stability/boarding under pressure/limit equilibrium method
维普
万方数据