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研究三向应力作用下裂隙对岩石力学特性的影响对于确保裂隙岩体工程稳定具有重要的实践意义。通过配制含两条不平行张开贯穿型裂隙类砂岩试样,采用MTS815.02岩石力学伺服试验机进行不同围压下常规三轴压缩试验。基于试验结果,详细分析了完整及断续不平行双裂隙类岩石材料的应力–应变曲线、强度和变形参数以及破裂模式。研究结果表明:1断续裂隙岩样应力–应变曲线呈现多台阶式软化,部分曲线出现双峰值现象;2完整及断续裂隙岩样峰值强度、裂纹损伤阈值和峰值应变均随着围压的增大呈线性增大。完整岩样峰值强度对围压的敏感程度最高,而断续裂隙岩样中由倾角45°,30°和60°依次减小;3断续裂隙岩样宏观破裂模式受裂隙倾角和围压的共同作用。当围压较小时,破裂形态受裂隙倾角的影响较大;当围压增大到一定程度后,裂隙倾角的影响逐渐减弱,围压的作用开始显现,岩样最终呈剪切破坏模式。
Studying the influence of cracks on the mechanical properties of rock under three-direction stress is of important practical significance for ensuring the stability of fractured rock mass. Three triaxial compression tests under different confining pressures were carried out by using MTS815.02 rock mechanics servo test machine with two sandstone samples with non-parallel open fractures. Based on the experimental results, the stress-strain curves, strength and deformation parameters and fracture modes of intact and discontinuous non-parallel double-fractured rock materials are analyzed in detail. The results show that: 1, the stress-strain curves of fractured fractures show multi-step softening with bimodal phenomena in some curves; 2 the peak strength, crack damage threshold and peak strain of intact and discontinuous fractures are both with the confining pressure Increase linearly. The peak intensity of intact rock sample is the most sensitive to confining pressure, while the discontinuous fractured rock samples decrease in turn from 45 °, 30 ° and 60 °. 3 The macroscopic rupture pattern of fractured rock samples is affected by the dip angle and confining pressure collective effect. When the confining pressure is small, the rupture morphology is greatly influenced by the crack dip angle. When the confining pressure increases to a certain extent, the effect of confining fracture angle gradually weakens and the confining pressure begins to appear. The rock specimen finally appears the shear failure mode.