基于能量耗散的应力引起的土体各向异性模型

从热力学定律出发,介绍了土体受力变形过程中能量耗散函数的合理表达形式,据此导出耗散应力空间中的屈服函数及流动法则.分析迁移应力,确定了真实应力空间中的屈服函数,并采用旋转硬化规律考虑应力引起的土体各向异性.这种模型以自由能函数和耗散函数为基础进行整体构造,自动满足热力学第二定律,不需要引入其他假定.提出了利用弹塑性本构模型计算三轴试验曲线的方法.采用遗传优化算法拟合了某土料三轴排水剪切试验结果,确定了模型参数.用得到的模型参数计算绘出其他固结应力下三轴排水剪切曲线,并与实测曲线比较,验证了模型的有效性.

A soil anisotropic model induced by stress based on energy dissipation

Starting from the thermomechanics principles,a proper form of energy dissipation function in the process of soil deformation was introduced,from which the yield locus and flow rule in dissipative stress space were deduced.Then the shift stresses were analyzed to specify the yield locus in true stress space and rotational hardening law was adopted to embody the anisotropy induced by stresses.Based on the free energy and dissipation functions,the models deal with all aspects of constitutive equations in a systematic manner,thereby they satisfy the laws of thermodynamics automatically,and there is no need to invoke any other postulates.The method to calculate the triaxial test curves was presented.Employing the genetic algorithm,the model parameters were identified by fitting the data of triaxial drained test.Then the parameters obtained were used to calculate the drained test curves for other consolidated pressure conditions,and these curves were compared with observed data in corresponding cases.It is shown that the results are satisfying and the model is available.