Terzaghi Loosening Soil Pressure Considering Cohesion and Partially Mobilized Arching

With principle stress rotation on the slip surface and burial depth being taken into account, the coefficient of lateral earth pressure on shearing planes is derived by adopting Mohr-Coulomb criterion, and the vertical stress on shearing planes is deduced with the differential soil strip limit equilibrium method. Further, vertical stress distribution and average vertical stress between shearing planes are deduced with circular arc being selected as the minor principal stress trajectory to embody the effect of partially mobilized arching. The results demonstrate that: Vertical stress on shearing planes derived in this paper, compared with the traditional Terzaghi loosening earth pressure equation and its existing modified equations, is more dramatically influenced by soil cohesion and internal friction angle and both factors’ influences are enhanced by principle stress rotation; Soil cohesion exerts the same impact on the distributions of vertical stress and coefficient of lateral earth pressure between shearing planes, namely greater soil cohesion leads to more prominent non-linear distributions; Vertical stress distribution between shearing planes obtained from taking the minor principal trajectory as arc is generally consistent with the in-situ test results of Yang Minghui et al. and average vertical stress above trap door also fits well with the experimental data from Chevalier et al.