单轴拉伸条件下脆性岩石微裂纹损伤模型研究

INVESTIGATION ON THE MICRO-CRACK DAMAGE MODEL OF BRITTLE ROCK UNDER UNIAXIAL TENSILE LOADING

利用断裂力学、损伤力学和均匀化原理,对脆性岩石单轴拉伸条件下的力学特性进行分析,建立了脆性岩石的微裂纹损伤本构模型.首先对岩石内部微裂纹的统计分布规律进行分析,给出了理论分析过程中微裂纹分布的假设条件,在此基础上,参考已有研究成果,得到含细长微裂纹脆性岩石有效弹性参数的计算公式.然后,对岩石内部单一微裂纹进行断裂力学和损伤力学分析,得到了扩展裂纹尖端的应力强度因子计算公式,在一定微裂纹断裂扩展准则和断裂扩展速率的假设基础上,利用积分原理,得到了岩石整体的损伤变量和损伤演化方程,由此建立单轴拉伸条件下脆性岩石的微裂纹损伤本构模型.最后,通过一花岗岩的单轴拉伸试验结果对微裂纹损伤本构模型进行了验证.

Based on the fracture mechanics,damage mechanics and harmonization theory,a micro-crack damage constitutive model is established through considering the mechanical characteristic of brittle rock under uniaxial tensile loading. Firstly, the statistical distribution orderliness of micro-crack in the rock is analyses,the supposition of distribution of micro-crack in the process of theory analyses is present, and other research results are referenced, the effective elastic parameters formula of brittle rock which contains a lot of spindly micro-cracks is got. Secondly, the fracture mechanics and damage mechanics of single micro- crack in the rock are analysed, base on some supposition of fracture failure criterion and fracture extend speed of micro-crack,and the integral theory is used, so that the damage variable and damage evolution function of rock is created, then the micro-crack damage model of brittle rock under uniaxial tensile loading is established. Finally,the micro-crack damage model is validated through a uniaxial tension experimental result of granite.