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合理的砂土本构模型不仅要能够描述砂土的剪胀性和应变软化,同时还要能反映土体三维应力空间的真实特性,因此不能只建立在代表轴对称状态的常规三轴试验基础上。在室内真三轴试验的基础上,对Mohr-Coulomb强度准则的形状函数进行了改进,可以更准确地反映砂土三维应力状态下的变形和强度特性。同时考虑应力水平相关剪胀性与应变软化特征,建立了一个适用于粉细砂的三维本构模型。通过对上海粉细砂常规三轴和真三轴试验结果的数值模拟,验证了模型的合理性和有效性。
Rational sand constitutive model not only can describe the dilatancy and strain softening of sand, but also can reflect the true characteristics of soil three-dimensional stress space. Therefore, it can not be established only on the basis of conventional triaxial test that represents axisymmetric state on. Based on the true triaxial test, the shape function of Mohr-Coulomb strength criterion is improved, which can reflect the deformation and strength characteristics of sand under three-dimensional stress state more accurately. At the same time, considering the stress level related dilatancy and strain softening characteristics, a three-dimensional constitutive model for silty sand was established. Through the numerical simulation of the conventional triaxial and true triaxial tests of silty sand in Shanghai, the rationality and effectiveness of the model are verified.