基于Hoek-Brown准则的岩体弹塑性损伤模型及其应力回映算法研究

为了克服一般弹塑性损伤模型不能反映岩体结构、岩块强度、应力状态的影响以及非线性破坏特征等问题，该文基于广义的Hoek-Brown（HB）屈服准则，考虑损伤引起的刚度退化和塑性导致的流动两种破坏机制的耦合作用，同时引入修正有效应力原理来考虑孔隙水压力的作用，建立了岩体弹塑性损伤本构模型，给出了损伤变量定义及演化方程。针对该模型在数值求解过程中存在的奇异点问题，从主应力空间推导了弹塑性损伤模型的完全隐式返回映射求解算法，包括弹性预测、塑性修正和损伤修正三个步骤。通过ABAQUS软件的用户子程序接口Umat，实现了弹塑性损伤模型的数值求解过程。采用单轴、三轴压缩试验和隧道算例对模型算法进行验证和分析，结果表明，所建立的HB损伤本构模型能够很好地描述岩体材料的力学特性，在实际岩体工程的损伤模拟中效果令人满意，计算结果对工程有指导意义。

AN ELASTOPLASTIC DAMAGE CONSTITUTIVE ROCK MODEL AND ITS STRESS MAPPING ALGORITHM BASED ON HOEK-BROWN CRITERION

In order to overcome the problem that the general elastoplastic damage model cannot reflect the influence and nonlinear failure characteristic of rock mass,rock strength,and stress state,it established an elastoplastic damage model based on Hoek-Brown criterion,considering the coupling effect of two failure mechanisms,namely stiffness degradation due to damage and plastic flow.The modified effective stress principle is introduced to consider the effect of pore water pressure.The damage variable definition and evolution equation are developed.The fully implicit return mapping algorithm in the principal stress space is derived,using three steps:elastic trial,plastic correction and damage correction.The calculation progress is implemented in Umat of ABAQUS.Uniaxial and triaxial compression tests and tunnel examples are adopted to verify and analyze the model algorithm.The results show that the model can well describe the mechanical properties of rock mass materials,and the effect is satisfactory in the damage simulation of practical rock mass engineering,and the calculated results are of guiding significance to engineering.