砂土的应力路径本构模型

将微元应力路径线性逼近，转变成与其充分接近且易于计算应变的等平均应力微元和等应力比微元，计算任意加荷应力路径所产生的塑性应变，建立了双屈服面的砂土应力路径本构模型．模型体现了岩土塑性理论分量屈服和非关联流动法则的要求，在p，q平面内根据双线性的屈服线确定了加卸载准则．结合广义非线性强度理论采用变换应力三维化方法简单、合理地使模型实现三维化．通过试验数据的验证表明，砂土应力路径本构模型可以合理地描述各种应力路径下砂土的变形和强度特性。

Constitutive model of sand considering complex stress paths

The relativity of stress path is an important mechanical behavior of soils. In this paper, by the means of equivalently approaching the infinitesimal of stress path, it is decomposed into two parts, one of which is in the infinitesimal of constant hydrostatic pressure and the other is in the infinitesimal of constant ratio of shear stress to hydrostatic pressure. The plastic strain, which is caused in random stress paths under loading conditions, can be calculated easily by using this method. According to this idea, we propose a constitutive model of sand, which can consider the influence of stress path. There are two linear yield surfaces in p-q plane. The loading criterion is easily determined based on these yielding surfaces. Using transformed stress method, it is easy and reasonable to combine the model with the Generalized Non-linear Strength Theory to make the model describe complex stress states. The model can rationally describe the characteristics of deformation and strength of sand under various stress paths.