孔隙压力对圆形巷道围岩破坏过程中声发射及能量释放的影响

Influence of pore pressure on acoustic emission and energy release in failure process of a circular tunnel surrounding rock

利用FLAC模拟了不同孔隙压力条件下圆形巷道围岩破坏过程中的声发射及能量释放规律。在计算中,采用了应变软化本构关系及"先加载,后挖洞"方式。模拟结果表明:随着时步的增加,在平衡之前,3种破坏单元数(剪切、拉伸破坏单元数和破坏单元总数)及两种释放的能量(剪切和拉伸破坏释放的能量)都具有间歇式上升的特点;当孔隙压力很低时,开挖巷道之后的围岩易于重新达到静力平衡状态;随着孔隙压力的增加,在相同的时步时,上述5种量通常都增加;随着孔隙压力的增加,两种能量释放现象出现的次数越来越多。还比较了声发射率与能量释放率计算结果的差异。

Acoustic emission and strain energy release in the failure process of a circular tunnel surrounding rock at different pore pressures were modeled by using FLAC.A strain-softening constitutive relation was used and a tunnel was excavated after the model was loaded to reach a static equilibrium state.Numerical results showed that three kinds of failed element numbers in shear,tension and in both,and two kinds of released energies（due to shear and tensile failures） intermittently increased with the timestep.At lower pore pressures,the excavated surrounding rock can easily reach the second equilibrium state,while at higher pore pressures,the excavated surrounding rock cannot reach the equilibrium state.At the same timestep,the five quantities mentioned above increase generally with the pore pressure.The number of the two kinds of released energy phenomena increase with the pore pressure.In addition,the acoustic emission rate and two kinds of energy release rates are compared and the apparent difference between them is found.