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通过引入应力Lode角建立合理的角隅函数描述偏平面形状,对三维Mohr-Coulmb强度准则进行修正,使之能合理反映中主应力比对土体峰值内摩擦角的影响。修正后的准则在偏平面上的强度线与Lade-Duncan准则相似,但更具灵活性,预测结果更符合松砂真三轴试验结果。由于土体在加载过程中常发生应变局部化现象,导致其强度得不到充分发挥。基于非共轴塑性模型的分叉分析研究了应变局部化发生对土体强度发挥的影响,通过与密砂真三轴试验结果对比表明,分叉强度能合理反映在不同中主应力比条件下应变局部化发生对土体强度的降低作用。
By introducing a reasonable corner function by introducing the stress Lode angle and describing the shape of the flat surface, the three-dimensional Mohr-Coulmb strength criterion is modified so that the effect of the intermediate principal stress ratio on the peak internal friction angle can be reasonably reflected. The revised criterion is similar to the Lade-Duncan criterion in the intensity line on the flat surface, but it is more flexible and the prediction results are more in line with the true triaxial test of loose sand. Due to the localized strain of soil during loading, soil strength can not be fully utilized. Based on the bifurcation analysis of non-coaxial plasticity model, the effect of strain localization on soil strength was studied. Comparing with the true triaxial test of sandstone, the bifurcation strength can be reasonably reflected in different medium stress ratio Strain localization occurs on the reduction of soil strength.