矿山围岩蠕变破坏过程数值模拟

Numerical Simulation of Creep Failure Process of Mine Surrounding Rock

摘要: 矿山开采中围岩的蠕变特性是影响岩体工程长期稳定的重要因素。本文在幂函数模型基础上，基于损伤力学理论，建立了能够描述加速蠕变过程的非线性蠕变损伤模型。模型采用最大拉应变准则和摩尔–库仑准则作为损伤判断准则。借助有限元分析软件编程实现该模型的数值求解。首先将数值模拟得到的结果与已有试验数据进行对比分析，验证了模型的正确性。然后进行了单轴和三轴压缩蠕变数值模拟，模拟得到了岩石蠕变破裂的3个典型阶段，即初始、稳定和加速蠕变阶段。研究结果表明：所建立的蠕变模型适合于模拟预测岩石的蠕变破坏，复杂的宏观蠕变破坏可以用细观单元的损伤来解释。

Abstract: Creep property of rock mass has a significant impact on the stability of underground constructions. On the basis of classical power-law creep model, the time-dependent creep behavior of rock is in-vestigated based on damage mechanics principle, in which the damage evolution is considered as a key factor dominating the accelerating creep and a damage-based constitutive law for tertiary creep is proposed. The maximum tensile strain criterion and the Mohr-Coulomb criterion are utilized as two damage thresholds to control the rock damage. Then the damage-based creep model is implemented using finite element method by MATLAB programming, a powerful PDE-based multiphysics modeling environment. The model is firstly validated by comparing the numerical results with the previously published experimental observation and then used to simulate the rock creep under uniaxial and biaxial compression. The model accurately reproduces the classic tri-modal behaviour (primary, secondary and tertiary creep) seen in laboratory creep (constant stress) experiments. So the fact shows that the rheological model is appropriate to predict the nonlinear creep failure of rocks, and the complex macroscopic time-dependent behavior can be mechanically explained by the material degradation (damage) at the mesoscale.