不同围压下含天然贯通节理岩石卸载破坏机理研究

二郎山特长高速公路隧道断裂带较多，受此影响，隧道开挖后岩爆灾害十分严重．从此隧道中取样制备成含天然贯通节理试件，进行常规单轴压缩室内试验，获取基本力学参数和破坏模式．本文以室内实验结果为依据，确定数值试验时所采用的岩石和节理的力学参数，利用RFPA软件开展数值试验，研究了不同围压同轴向荷载下卸掉围压诱发岩石失稳破坏机理．试验结果表明，五种不同围压(5、10、15、20、25 MPa)卸载后应力-应变曲线均呈“断崖式”跌落，试样均突然破坏，与现场岩爆情况吻合；受贯通节理影响，不同围压试样的具体破坏形态、声发射数量最大值出现时刻有所差异；在卸载阶段五种试样声发射累积数量都突然急剧增大．

Unloading Failure Mechanism of Rock with Natural Transfixion Joint under Different Confining Pressures

There are abundant fault zones in Erlang mountain super-long expressway tunnel, which causes serious rock burst disaster after tunnel excavation. Rocks were taken from the tunnel to make specimens with natural transfixion joints, and the conventional uniaxial compression tests were conducted in the laboratory to obtain the basic mechanical parameters and failure modes. First the mechanical parameters of rock mass and joint used in the numerical experiment are determined from the laboratory test. Then, the numerical test of rock failure induced by the unloading under different confining pressures and identical axial load is carried out by RFPA software. The mechanism of rock failure is studied. The test results show that the stress-strain curves of five different confining pressures (5, 10, 15, 20 and 25 MPa) drop abruptly after unloading and the specimens are destroyed suddenly, which is consistent with the rock burst situation in the practical field. The specific failure mode and the moment corresponding to the maximum acoustic emission number are different among the specimens with different confining pressures due to the through-going joints. The acoustic emission cumulative numbers of the five kinds of specimens all suddenly increase during the unloading stage.