【摘要】 通过不同吸力状态下的非饱和土抗剪强度试验,探讨了基质吸力对黏聚力和摩擦角的影响,提出在不同的基质吸力条件下黏聚力和摩擦角均可能是变化的。非饱和土的抗剪强度包络面在几何学上是直纹面的一种,该包络面可用改进的摩尔-库仑破坏准则描述,并用试验验证了该公式的合理性。结合改进的摩尔-库仑抗剪强度公式和具体试验,提出了等效黏聚力-吸力曲线和等效摩擦角-吸力曲线在一定的区间内近似为直线,给出了确定等效黏聚力和等效摩擦角的具体方法,并用干土和饱和土两种极端状态对3种非饱和土抗剪强度理论进行了评估。改进的摩尔库仑破坏准则是一种更真实描述非饱和土破坏的强度准则。

【Abstract】 Based on three unsaturated soil shear strength tests,it is found that the Mohr-Coulomb failure surface is a ruled surface.The improved Mohr-Coulomb failure theory is suggested to describe the failure surface.And then,to get the index of the Mohr-Coulomb failure theory,equal cohesion-suction curve and the equal fraction angle-suction curve are suggested.Finally,several shear strength theories are evaluated by drying soils and saturated soils.Improved Mohr-Coulomb failure theory can describe the failure of unsaturated soils.