土体的各向异性及近似模拟

Anisotropy of soils and its approximate simulation

通过真三轴仪试验 ,分别从 3个主应力方向加荷 ,研究产生的应变分量变化 ,从而较清楚地揭示了土体中显著的由应力引起的各向异性。在此基础上提出了土体应力应变柔度矩阵所具有的性质 ,即不同应力方向上加荷所引起的应变分量之间关系的规律 ,这些规律是检验土体本构模型合理性和适用性的重要标尺。依据这些性质 ,提出了一种以邓肯模型为基础修正的各向异性本构模型 ,对于不同的应力方向 ,采用不同的弹性模量和泊松比 ,模型参数与邓肯模型一致 ,由常规三轴试验确定 ,它是一个经验的、但实用性强的各向异性本构模型。

A series of true triaxial tests were performed with loading in directions of three principal stresses respectively. The obvious anisotropy induced by stress state were discovered. Based on the test results, the characteristics of the stress-strain softness matrix of soils, which indicate the rules of the relationship of the strain components in different stress directions, are proposed. These rules can be used to check whether a soil constitutive model is reasonable and suitable. In accordance with these characteristics, a constitutive model, which is based on Duncan's hyperbolic model but modified to reflect the anisotropy, was developed. In different stress directions, Young's modulus and Poisson's ratio are different. The parameters of this model can be determined using ordinary triaxial tests, which are just the same as those in the hyperbolic model. The model is an experiential but practical anisotropic model of soils.