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结构性土体的力学特性具有明显的损伤破损效应。根据岩土材料复合体损伤理论,结构性土体可看作是由结构相和损伤相各占一定比例的复合材料。结构性土体的损伤过程本质上是土体中结构相的变形能向相变损伤耗散能转化,相变损伤耗散能促使结构相退变为损伤相的损伤发展过程。从任意方向截面上看,结构相表面损伤后即变为损伤相的表面。基于此认识,把结构性土体的损伤变量与结构相、损伤相所占的截面面积联系起来,从而与经典连续介质损伤力学中关于损伤变量的定义一致。将土体结构的损伤引起的外力多做的那部分功定义为相变损伤耗散能,并将此引入到土体的能量平衡方程中。通过对结构性土代表体元的能量分析,推导了基于结构损伤耗能条件下的损伤演化方程,给出了模型参数的确定方法。最后将试验结果和本文方法的结果进行对比,表明本文方法能较好反映土体损伤演化规律。
The mechanical properties of structural soil have obvious damage and damage effects. According to the damage theory of composite geomaterials, structural soil can be regarded as a composite material composed of a certain proportion of structural phase and damage phase. The damage process of structural soil is essentially the transformation of the deformation energy of the structural phase in the soil to the phase transition damage, and the dissipation of phase transformation damage can cause the structure to degenerate into the damage development of the damage phase. Seen from the cross-section in any direction, the surface of the structural phase becomes the surface of the damaged phase. Based on this understanding, the damage variable of structural soil is related to the cross-sectional area occupied by structural phase and damage phase, which is consistent with the definition of damage variable in classical continuum damage mechanics. The part of work done by the external force caused by the damage of soil structure is defined as the dissipation energy of phase transformation damage and introduced into the energy balance equation of soil. Based on the energy analysis of voxels on structural soil, the damage evolution equations based on structural damage and energy dissipation are deduced, and the method for determining the model parameters is given. Finally, the experimental results and the results of this paper are compared, indicating that this method can better reflect the evolution of soil damage law.