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水压会刺激岩石裂纹的产生和加速岩石破裂,对岩石的变形破坏特征和破坏机制有重要影响。利用MTS815 Flex Test GT岩石力学试验系统和PCI-Ⅱ声发射仪开展了砂岩在不同围压下的水-力耦合试验。结果表明:在整个岩石破裂过程中,声发射活动随加载时间、应力变化表现出不同的特征;声发射活动在岩石的峰后阶段随着水压的增大更为集中,强度也更高,而随着围压的增大其集中程度和强度都有所降低;在相同围压下,声发射累计振铃计数和累计能量随着水压的增大而增大,在相同水压下,声发射累计振铃计数和累计能量则随着围压增大而有所减少;随着水压的增大,岩石最终失稳破坏时刻的声发射三维定位图中裂纹数量增多,裂纹的集中程度也更高,在宏观破坏形态上表现出破坏角减小。这些成果揭示了水-力耦合作用下岩石的破坏机制由压制剪切向压制张裂变化,岩石破裂的脆性破坏特征增强。
Water pressure will stimulate the generation of rock cracks and accelerate the rock rupture, and have an important influence on the deformation and failure mechanism and damage mechanism of rocks. The MTS815 Flex Test GT rock mechanics test system and the PCI-Ⅱ acoustic emission device were used to test the water-power coupling of sandstone under different confining pressure. The results show that during the entire rock rupture, the acoustic emission activity shows different characteristics with the loading time and stress changes. Acoustic emission activity is more concentrated and the intensity is higher with the increase of water pressure in the post-peak stage of rock. But with the confining pressure increasing, the concentration and intensity are reduced; under the same confining pressure, the cumulative ringing count and accumulated energy of acoustic emission increase with the increase of water pressure. Under the same water pressure, Acoustic emission cumulative ring counting and cumulative energy decrease with the increase of confining pressure. With the increase of water pressure, the number of cracks in the acoustic emission three-dimensional positioning map at the final failure of rock failure increases, and the concentration of cracks Also higher, demonstrating a decrease in damage angle in the macro-damage morphology. These results reveal that the failure mechanism of rock under water-power coupling changes from compressive shear to compressive cracking, and the brittle failure characteristics of rock failure are enhanced.