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利用自主研发的煤岩剪切细观试验装置,以砂岩为研究对象,开展了不同饱和度数条件下的岩石剪切细观开裂演化与贯通机制试验研究,分析了砂岩剪切细观开裂演化过程和贯通机制,探讨了饱水系数对细观开裂和裂纹形态特征的影响。研究结果表明:剪切过程中,伴随着应力降,裂纹一般首先出现在剪切面中部,几条裂纹间断分布,距离较近的裂纹相互连通形成大裂纹,在应力继续下降的一瞬间,各裂纹连通形成贯通面;水的弱化作用影响了岩石的强度,使得试件底部出现较大的次级裂纹;饱水系数越大,分叉裂纹越多,使得试件的表面裂纹形态更加复杂,断裂面弯折段的数目越多,下端部次级裂纹越发育,整体损伤范围越大;细观上,局部独立裂纹贯通过程伴随着胶结颗粒岩桥的梁式旋转和弯曲折断,水的弱化作用,使得岩桥内部和外部微裂纹增多;随着饱水系数的增加,岩石剪切过程中出现的独立和次级裂纹的数目均呈增加趋势。
Using self-developed coal-rock shear meso-observing device, taking sandstone as the research object, we carried out experimental study on meso-crack evolution and penetration mechanism of rock under different saturation conditions, and analyzed the evolution process of shear meso- And penetration mechanism, discussed the influence of saturated water coefficient on meso-cracking and crack morphological characteristics. The results show that in the process of shearing, the cracks usually appear first in the middle of the shear surface with the stress drop, and the cracks are intermittently distributed. The cracks with close distance form a large crack. When the stress continues to drop, The crack is connected to form a through surface; the weakened effect of water affects the strength of the rock, resulting in a larger secondary crack at the bottom of the specimen; the larger the saturated water coefficient, the more bifurcated cracks make the surface crack morphology more complicated, The more the number of bending sections of the fracture surface, the more the secondary cracks propagate at the lower end, the greater the damage range is. On the meso-scale, the local independent crack propagation process is accompanied by the beam rotation and bending fracture of the cement granular rock bridge and the water weakening Which can increase the internal and external microcracks in the rock bridge. With the increase of the saturated water coefficient, the numbers of independent and secondary cracks in the rock shearing process both increase.