考虑中间主应力的原位岩体强度参数取值研究

Study on strength parameters of in-situ rock mass considering intermidiate principal stress

为了研究深部隧洞或地下厂房围岩在三向应力状态下的强度特性,开展玄武岩和片岩原位真三轴卸载试验,基于Mohr-Coulomb强度准则和Mogi强度准则,探讨考虑中间主应力影响的岩体强度参数取值问题。分析结果表明:(1)对于玄武岩和片岩原位真三轴试验,采用Mohr-Coulomb强度准则的回归方程满足显著性水平?=0.05的检验要求,采用Mogi强度准则的回归方程则可满足显著性水平?=0.01的检验要求,因此采用Mogi强度准则拟合现场岩体真三轴试验结果更加可靠;(2)考虑中间主应力影响的Mogi强度准则确定的岩体抗剪强度参数?值比忽略中间主应力影响的Mohr-Coulomb强度准则确定的?值高约6%,但是Mogi强度准则确定的岩体抗剪强度参数c值,则比Mohr-Coulomb强度准则确定的c值低约60%。

In order to research the strength characteristics of the surrounding rocks in deep tunnels and underground powerhouses, two series of in-situ true triaxial tests for basalt and schist rock masses were carried out. Then, based on Mohr-Coulomb and Mogi criteria, evaluation of strengthen parameters considering the intermediate principal stress was discussed. The research indicated that, according to the strength values of basalt and schist rock masses obtained by in-situ true triaxial tests, the Mohr-Coulomb criterion regression equations passed the F-test at a significance level of 0.05, however, the Mogi criterion regression equations passed the F-test at a higher significance level of 0.01. Therefore, using Mogi criterion may be better to analyze the in-situ true triaxial tests data. The values of strength parameter φ calculated by Mogi criterion considering the intermediate principal stress were higher 6% than the values calculated by Mohr-Coulomb criterion ignoring the effect of the intermediate principal stress. But, the values of strength parameter c calculated by Mogi criterion were lower 60% than the values calculated by Mohr-Coulomb criterion.