中文摘要：

目的建立服从热力学第一定律通用的吉布斯自由能函数,解决循环荷载作用下的应变累积问题.方法采用数学软件Mathematic来解非线性最小二乘法拟合不排水3轴试验点,得到模型计算参数.建立压力相关的剪切模量的能量势函数的推导框架,采用热力学方法对柔度矩阵进行修正.结果产生了弹性体积与弹性剪切反应的耦合,耦合的幅值反应了材料各向异性的程度,由应力比确定;剪切模量对压力的依赖性在体积模量中产生了弹性剪胀部分.结论对不同闭合应力路径的计算结果表明,修正后的模型满足能量守恒.

英文摘要：

The bulk modulus is usually defined through the pressure-dependent expression and the shear modulus is then obtained by assuming a constant Poisson＇s ratio for the Modified Cam-Clay model.This model can result in behavior that violates the First Law of Thermodynamics.In this paper,a framework within which a pressure dependent shear modulus can be accommodated in a theoretically acceptable manner is described.In the modified compliance matrix,by use of thermodynamic approach,there exists coupling between elastic volumetric and elastic deviatoric behavior.The magnitude of this coupling reflects a degree of material anisotropy,which is determined by the value of the stress ratio.Moreover,dilatancy term occurs in the bulk modulus due to shear modulus dependency on pressure.The parameters are calibrated by applying the nonlinear least square multiple method in software Mathematic to fit the undrained triaxial test points.The computational results indicate that modified model satisfies energy conservation for different closed-loop stress paths.