高地应力作用下隧道围岩三轴压缩破坏机制分析

Analysis of Triaxial Compression Failure Mechanism of Tunnel Surrounding Rock Under Highland Stress

为研究高地应力隧道围岩的力学特性,以辽宁某在建隧道项目为工程背景,以三轴试验中的围岩来模拟实际岩体所处的高地应力环境,采用MTS815.02三轴试验系统对该隧道围岩(砂岩)展开研究,分析各力学参数在高围压下的分布规律.结果表明:在较高围压作用下,砂岩应力-应变曲线变化趋势与低围压下大体一致;随着围压的逐渐增大,砂岩的峰值强度、弹性模量、轴向峰值应变、径向峰值应变均随围压呈逐渐递增变化,泊松比随围压呈逐渐递减变化,且在高围压下,各力学受影响程度依次为:峰值应变>峰值强度>弹性模量>泊松比;对各力学参数随围压的分布曲线进行拟合发现,各力学参数与围压之间均满足指数函数关系,拟合相关度均在0.95以上,表明各力学参数与围压之间具有较强的相关性,且各参数增幅逐渐减小.

To study the mechanical properties of high geostress surrounding rock,based on the engineering background of a tunnel project under construction in Liaoning,based on the surrounding rock triaxial test to simulate the actual rock mass of high ground stress environment,MTS815.02 triaxial test system of the tunnel surrounding rock(sandstone)study is used to analyze mechanical parameters under high confining pressure distribution.The results show that under higher confining pressure,sandstone stress-strain curve change trend and broadly under low confining pressure.As the confining pressure gradually increases,the peak strength,elastic modulus,axial peak strain and radial peak strain of sandstone gradually increase with the confining pressure,and the Poisson's ratio gradually decreases with the confining pressure.Under high confining pressure,the degree of influence of all mechanics is as follows:peak strain>peak strength>elastic modulus>Poisson's ratio.By fitting the distribution curve of mechanical parameters with confining pressure,it is found that the linear function relationship between the mechanical parameters and confining pressure is satisfied,and the fitting parameters are all above 0.95,indicating that there is a strong correlation between the mechanical parameters and confining pressure.