基于能量耗散原理的非均质岩石损伤破坏元胞自动机模型研究

基于能量耗散理论建立非均质岩石的动态损伤破坏元胞自动机,分析单轴压缩试验中岩石破坏截面的损伤状态,得到该情况下的岩石裂隙微观动态发展过程、损伤演化关系以及全程应力应变曲线。研究发现：①加载过程中,均质度较低的岩样裂纹的萌生和扩展较为分散,损伤速率低;均质度较高的岩样裂纹的萌生和扩展非常集中,表现为脆性破坏。②损伤演化曲线呈3阶段S形发展。③随着岩石均质度参数的增加,岩石的峰值强度和峰值应变都有所提高,峰后曲线越来越陡。④给出的衡量岩石脆性破坏强弱程度的指标参数,能够较好地描述岩石破坏形式随着均值度参数m变化的规律。

Simulation of Rock Failure with Mh-pca Model Based on Principle of Energy Dissipation

In order to quantify the rock damage evolvements in the rock failure event of uniaxial stress state,a micro-heterogeneous physical cellular automata model（MH-PCA model）is introduced based on energy dissipation theory.The macroscopic dynamic process of rock fracture, damage evolution and complete stress-strain curve under uniaxial compression condition are obtained.The results show：1.In the process of loading,for the rock sample with lower homogeneous degree,the crack initiation and propagation are relatively dispersive,the cracks develop completely and the damage grows slowly;while for the rock sample with higher homogeneous degree,the crack initiation and propagation occur in concentrated zone,the cracks develop incompletely and brittle failure occurs eventually.2.The damage evolvements can be described by an S-shaped cumulative model.There is a large proportion of the second stage to the whole curve, large slope,large damage evolution speed and obvious brittle failure for the rock with larger homogeneous degree.3.With the parameter mincreasing,the peak strength,peak strain and softening modulus of this kind of rock increase.It is not only the average strength but also the homogeneous degree and energy dissipation rate that affect the peak strength.4.A parameter for describing the brittle characteristic of rock is given.The parameter can distinguish the failure phenomena of rock with different homogeneous degrees.Meanwhile,we find out that there is a critical value mcrfor the parameter m.When the homogeneous degree is larger than m,the rock has a distinct brittle failure pattern.When the homogeneous degree is lower than m,the rock has a distinct plastic flow failure pattern.The derived results coincide with the practice and it is very helpful for us to understand the relationship between the microscopic damage and macroscopic failure of rock.