堆积软岩的黏弹塑性本构模型及其数值计算应用

 堆积软岩的主要力学特性有应变软化、流变、受中间主应力影响等，为了尽可能完整地描述这些力学特性，提出一个全新的黏弹塑性本构模型。该模型基于下负荷面和tij概念，以超固结状态与正常固结状态之间的孔隙比差r为状态变量，并在该状态参量的演化律中引入非齐次函数，使模型能综合描述软岩的应变软化、流变和受中间主应力影响的力学特性。新模型仅比剑桥模型多了4个参数，而且4个参数都具有明确物理意义，可通过常规三轴试验确定。以降雨引起的软岩边坡的渐进性破坏为工程背景，用水土耦合有限元来探讨2种不同地下水位变化对边坡破坏的影响，从坡体的剪应变分布、位移矢量、破坏的传播等方面分析边坡的破坏机制。

VISCO-ELASTOPLASTIC CONSTITUTIVE MODEL FOR SEDIMENTARY SOFT ROCK AND ITS APPLICATION TO NUMERICAL CALCULATION

The sedimentary soft rock is a kind of geomaterial that exhibits the mechanical properties of strain softening，rheology，and influenced by the intermediate principal stress. In order to describe these properties as comprehensively as possible，a new visco-elastoplastic constitutive model is developed. Based on the tij concept and subloading surface，this model uses a state variable r which is a void ratio difference between the over- consolidated and normal consolidated states，and introduces a non-homogenous function as an evolution law for r. Compared to the Cam-clay model，only 4 new parameters are added to the new model，which have explicit physical meanings and can be determined from triaxial tests. A progressive failure of soft rock slope due to heavy rain is taken as background，and soil-water coupled FEM is conducted to investigate the influences of 2 kinds of groundwater table changes on the failure. The shear strain，displacement vector and propagation of the failure among the slope are analyzed carefully to clarify its failure.