断续裂隙类岩石材料三轴压缩力学特性试验研究

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。

Experimental study on mechanical behavior of rock-like materials containing pre-existing intermittent fissures under triaxial compression

It is of important practical significance for ensuring the stability of fractured rock engineering to investigate the influence of pre-existing fissures on the mechanical behavior of rock under three-dimensional stress. The rock-like material specimens containing two unparallel open penetrating fissures are fabricated in the laboratory. And then a series of conventional triaxial compressive tests on rock-like material specimens are carried out by using the MTS815.02 rock mechanics servo-controlled testing system. On the basis of experimental results, the stress-strain curves, strength and deformation parameters and failure modes are analyzed. The main conclusions are drawn as follows: (1) The stress-strain curves of pre-fissured specimens show multi-step softening, and some curves have two peak strengths; (2) The peak strength, crack damage threshold and peak axial strain of intact and pre-fissured specimens all increase linearly with the increase of confining pressure. The sensitivity to the confining pressure of intact specimen is the highest, and the sensitivity of pre-fissured specimens decreases from fissure angle 45° to 30° and then to 60°; (3) The failure modes of pre-fissured specimens are determined by the fissure angle and confining pressure. When the confining pressure is smaller, it is mainly affected by the fissure angle. Whereas the confining pressure is higher, which is mainly influenced by the confining pressure, and the rock specimens exhibit a shear mode.