地表超载作用下软土地区既有盾构隧道与地层的相互作用分析

Analysis of Interaction between Existing Shield Tunnel and Stratum under Surface Surcharge in Soft Soil Region

关于地表超载对既有盾构隧道的影响,现有分析计算理论将包含盾构隧道的地层视为完全土质地层,忽略了地表超载过程中既有隧道与地层相互作用导致的盾构隧道周围附加土压力。从盾构隧道上覆土层的土体间沉降状态来看,地表超载与隧道原有上覆土层对盾构隧道的影响不同,有必要单独考虑地表超载对既有盾构隧道的影响。在模型试验的基础上,开展既有盾构隧道与地层相互作用分析。结果表明:地表超载导致的既有盾构隧道附加土压力与隧道穿越土层、上覆土层及下卧土层的物理力学性能有关,也与盾构隧道的横向刚度有关;若按照现有理论计算软土地层中既有盾构隧道的允许地表超载,结果偏危险。

With respect to the influence of surface surcharge on existing shield tunnel,current analysis and calculation theories regard the stratum containing shield tunnel as a complete earth stratum,ignoring the additional earth pressure around the shield tunnel caused by the interaction between the existing shield tunnel and strata under surface surcharge.According to the settlement of the overlaying soils above the shield tunnel,the influence caused by the surface surcharge is different from that caused by the overlaying soil,and the influence upon the shield tunnel caused by the surface surcharge should be considered alone.Based on the model test,an analysis of the interaction between the existing shield tunnel and stratum under surface surcharge was conducted.The results show that the magnitude of the additional earth pressure around the existing shield tunnel caused by surface surcharge is connected with the physical and mechanical properties of the overlaying soil,the underlying soil and the tunnel passing soil,and is connected with the circumferential rigidity of the tunnel as well.If allowable surface surcharge over the existing shield tunnel in soft soil stratum is calculated by current theory,an unsafe result will be likely.