预制裂纹盐岩单轴力学特性及能量机制试验

盐穴储气库在水溶造腔时会产生大量溶蚀裂纹,为研究裂纹对盐岩强度和变形等力学性能的影响,利用MTS-815岩石力学实验系统,对不同参数裂纹盐岩的力学特性进行试验研究,采用对数应变对试验结果进行修正,分析了不同参数裂纹对盐岩的强度和变形的影响,并基于能量耗散理论分析其损伤破坏过程中的能量特征.结果表明:不同倾角裂纹降低了试样的峰值强度值,但降低量的多少与裂纹倾角大小未呈现明显的线性关系;不同长度的预制裂纹对盐岩峰值强度有明显的弱化作用,裂纹越长,弱化作用越大.外力做功产生的总应变能U绝大部分转化为耗散能Ud,小部分累积为可释放的弹性应变能Ue,导致盐岩内部产生损伤和塑性变形.破坏过程总能耗、耗散能、弹性应变能等,能量与应变关系曲线表现出明显的阶段特征;盐岩单轴压缩呈现压密阶段、弹性变形阶段、塑性变形阶段和破坏阶段等4个阶段.

Mechanical behavior and energy mechanism of salt rock with prefab fissures under uniaxial compression

A mass of corrosion fissures arise during the washing process of rock salt cavern. In order to study the influence of fissures on the mechanical properties of salt rock, the mechanical properties of the cracked salt rock with different parameters were tested and studied by using MTS-815 rock mechanics test system. The test results were modified by logarithmic strain, the effects of fissules with different parameters on the strength and the deformation of salt rock were analyzed, and the energy characteristics in the process of the damage were analyzed based on the theory of energy dissipation. The testing results indicate that the peak strength of salt rock with different fissure angles are lower than that of intact salt rock, and the relationship between the reduction extent and the fissure angle isn''t linear. The length of prefab fissure has obvious weakening effect on the peak intensity of salt rock. The longer the fissures are, the greater the weakening effect is. Most part of the total strain energy U produced by external force transforms into dissipated energy U_d, and a small part is accumulated as the releasable elastic strain energy U_e, which causes the damage and the plastic deformation in the salt rock. In the failure progress, the curves between energy, such as total energy consumption, dissipation energy and elastic strain energy, and strain present evident stage characteristics. The uniaxial compression of salt rock shows four stages: compression stage, elastic deformation stage, plastic deformation stage and failure stage.