中主应力对砂土抗剪强度影响的分析

土的抗剪强度参数一般通过三轴压缩试验确定。而三轴压缩试验中土的应力状态是轴对称的，这往往与实际工程中土体的受力情况不相同。因此，探讨一般应力条件下与三轴应力条件下强度指标之间的相互关系是至关重要的。基于砂土的空间滑动面强度准则即SMP准则，针对不同中主应力系数，通过数值分析探讨了中主应力系数对砂土抗剪强度指标的影响。分析结果表明，中主应力对土的抗剪强度指标具有显著的影响，一般地在平面应变条件下这种影响最大。

Evaluation of effect of intermediate principal stress on sand shear strength

The shear strength parameters of soils are conventionally obtained by soil triaxial compression tests in laboratory.However,the soils in engineering practice are not always in axisymmetric stress state as in conventional triaxial compression tests.Therefore,it is important to examine the inter-relationship between strength parameters under different stress states.Based on the spatial mobilization plane failure criterion proposed by Matsuoka and Nakai,the strength parameters for different intermediate principal stresses are generally compared.It is demonstrated that the intermediate principal stress ratio has a considerable effect on shear strength parameters of soils;and the effect will be the most significant under plane-strain condition.