土的三重屈服面应力-应变模型与SMP准则的结合

土的三重屈服面应力应变模型在国内有一定的影响力，它把土的塑性应变分成3部分，每一部分对应一个屈服面，分别为压缩屈服面、剪切屈服面和剪胀屈服面，从而在一定程度上反应了土的基本特性。但它在由三轴压缩应力状态向其它应力状态转化时，塑性系数需要重新确定，比较繁琐。而SMP准则能合理反映土的破坏特性，在国际上有一定的影响力。借用应力变换三维化方法，通过把土的三重屈服面应力应变模型和SMP准则相结合，使得原有的模型在不做任何假设的条件下，采用统一的塑性系数，由三轴压缩应力状态简单地转化到一般应力状态，并且能够考虑应变的分叉特性，能合理地预测已有的试验数据。

Combination of 3-yield surface model with SMP criterion

The 3-yield surface model developed by Shen(1984),is one of the most widely used model in civil engineering in China,which has three surfaces,compression yield surface,shear yield surface and dilatancy yield surface.The SMP criterion(Matsuoka and Nakai,1974;Matsuoka,1976) is one of the best criterions for the soil in the world.By using the transformed stresses,the 3-yield surface model is combined with the SMP criterion.The revised 3-yield surface model is the same as the original model in form.Comparisons with the experimental data show that not only it can well describe the stress-strain behaviors of the soil,but also can well describe the bifurcate behavior between the strains and stress.The transformed stress method is simple and effective.