Effect of inclined layered soils on face stability in shield tunneling based on limit analysis

Owing to complex and lengthy geological processes, inclined layered soils are frequently encountered in geological and geotechnical engineering. Tunneling in such strata threatens and reduces the stability of tunnel face. Most existing studies only focus on the effect of horizontal layered soils on face stability. Therefore, to evaluate the stability of tunnel face when shield tunnel excavated along inclined layered soil, a 3D rotating rigid body collapse mechanism based on limit analysis is improved using discretization technique. The critical support pressure and failure mechanism derived from this method are practicable by the comparison with the results deduced by numerical simulation and existing researches. Several design charts for different occurrence of in-clined strata are provided. The results show that the existence of inclined stratum will result in the asymmetric failure mechanism of tunnel face and the variation of active failure pressure. In addition, the proposed method is also used to analyze the stability of tunnel face under inclined ground. The results indicate that the dip of ground has a clear impact on the area of surface subsidence.

Automated summary

This article improves a 3D rotating rigid body collapse mechanism based on limit analysis using discretization technique, in order to evaluate the stability of tunnel face when shield tunnel is excavated along inclined layered soil. The results show that the existence of inclined stratum results in asymmetric failure mechanism of tunnel face and variation of active failure pressure.