【摘要】 为了揭示节理角度对阶梯状双裂隙大理岩疲劳劣化与失稳规律的影响机制，采用GCTS RTR-2000电液伺服岩石压力试验系统，对含有相同岩桥长度、不同节理角度(β=10°、30°、50°和70°)的双裂隙大理岩试样开展了增幅疲劳力学试验，并借助PCI-2声发射监测系统记录了岩石破裂过程中的振铃计数、能量、频率及振幅等基本参数，分析声发射频谱特性及b值特征。研究结果表明：随着节理角度逐渐增加，双裂隙对岩石的弱化作用逐渐减小，因此大理岩试样的强度、疲劳寿命、应变增长速率、刚度和累计声发射振铃(能量)计数等均随之增大；应变增长速率受应力幅值影响，在疲劳加载阶段末，表现为突增，且与强扩容现象以及累计振铃(能量计数)曲线的突变阶段相比，体积应变增长速率发生突变的阶段较为提前；随着节理角度增大，低频低幅及低频高幅信号占比逐渐增加，而高频高幅信号占比逐渐降低，越易产生大尺度裂纹；在疲劳加载最后一个阶段，试样发生严重的断裂破坏，声发射振幅统计指标b值出现骤降，且随着节理角度增大而增加。基于以上分析，体积应变增长速率首次突变阶段以及声发射b值的骤降阶段可以分别作为阶梯状双裂隙大理岩初始失稳以及最终破坏的前兆特征。更多还原

【Abstract】 This work aims to investigate the influence of joint angle on the fatigue deterioration and instability pattern of stepped-double fissure marbles. The fatigue mechanical tests of double fractured marble samples with different joint angles(β =10°, 30°, 50° and 70°) were carried out by using GCTS RTR-2000 electro-hydraulic servo rock pressure test system. The basic parameters such as ring count, energy, frequency and amplitude during rock failure were recorded by PCI-2 acoustic emission monitoring system and the characteristics of acoustic emission spectrum and b value were analyzed. The results show that with the increase of joint angle, the weakening effect of double fissure on rock decreases gradually, and so the strength, fatigue life, strain growth rate,stiffness and accumulative ringing/energy counts of marble samples increase. The strain growth rates are affected by the stress amplitude. At the end of the fatigue loading stage, there appears a sudden increase trend. The sudden change stage of the volume strain growth is earlier than the sudden change stage of strong expansion phenomenon and accumulative ringing/energy count curves. As the joint angle increases, the proportion of low frequency-low amplitude and low frequency-high amplitude signals gradually increases, while the proportion of high frequencyhigh amplitude signals gradually decreases, and large-scale cracks are more likely to occur. In the last stage of fatigue loading, the samples are seriously fractured, and the statistical index b value of acoustic emission amplitude decreases sharply, and increases with the increase of joint angle. Based on the above analysis, the first mutation stage of the volume strain growth rate and the sudden drop stage of the acoustic emission b value can be used as the precursory characteristics of the initial instability and final failure of the stepped double-fissure marbles, respectively.更多还原