基于应变率效应的岩石动态Mohr-Coulomb准则和Hoek-Brown准则研究

Rock dynamic Mohr-Coulomb and Hoek-Brown criteria based on strain rate effect

在考虑强度准则参数粘聚力c、内摩擦角φ和岩石材料常数m随应变率增加而变化的基础上,分别提出了基于应变率效应的岩石动态Mohr-Coulomb准则和Hoek-Brown准则。花岗岩材料在6种围压下的三轴试验结果表明:当应变率从10^(-4) s^(-1)增加到100 s^(-1)时,粘聚力c和岩石材料常数m均随应变率增加而增加,但是内摩擦角φ则随应变率增加而减小。为此,给出了上述3项参数随应变率变化的函数关系,并在此基础上,分别提出了考虑率效应的动态Mohr-Coulomb准则和Hoek-Brown准则表达式。通过理论计算结果与试验数据的对比,发现动态Mohr-Coulomb准则适应于低围压情况,而动态Hoek-Brown准则在低围压和高围压情况下均适用。

Considering the changes of strength criterion parameters cohesion c,internal friction angle φ and rock material constants m with the increase of strain rate,the rock dynamic Mohr-Coulomb criterion and Hoek-Brown criterion based on strain rate effect were proposed in this study.According to the triaxial experimental data of a granite under six confining pressures,the results show that,when the strain rate increases from 10-4 s-1 to 100 s-1,the cohesion c and rock material constants m increase,while the internal friction angle φ decreases with the increase of strain rate.The relationship between each strength criterion parameter and strain rate is given firstly.On this basis,the expression of dynamic Mohr-Coulomb criterion and Hoek-Brown criterion considering strain rate effect are presented,respectively.Through the comparison of theoretical calculation results with the experimental data,it can be concluded that the dynamic Mohr-Coulomb criterion is suitable for low confining pressure situation,while the dynamic Hoek-Brown criterion is applicable under low and high confining pressure conditions.