加载和卸围压条件下岩石力学特性的对比研究

Comparison of Mechanical Properties of Rock under Loading and Unloading Confining Pressure

为了研究岩石在加载和卸围压试验条件下的岩石力学特性,采用TAW-2000微机控制岩石伺服压力试验机,通过三轴加载和固定轴向应变卸围压的试验方法对辉绿岩进行了试验研究,分析了岩石在加载和卸围压条件下的岩石力学特性。并引入由Hoek-Brown屈服准则定义的主应力包络线切线,计算岩石峰值强度和残余强度时的粘聚力c和内摩擦角,获得了岩石在加载和卸围压条件下的岩石力学参数的变化特征。结果表明:在卸围压试验条件下,岩石在屈服破坏后,同样具有应变软化特性和破裂膨胀特性,但由于在卸围压条件下应变能的释放,岩石力学特性受围压的影响表现得更为突出。通过对加载和卸围压试验条件下的岩石力学参数进行比较分析,得到了岩石力学参数c、随围压的变化的规律。研究成果可为地下工程开挖过程中围岩受力变形特性研究提供参考。

Triaxial loading tests and unloading confining pressure tests were conducted with the TAW-2000 microcomputer-controlled servo rock compression testing machine,in order to study the rock mechanics properties under loading and unloading confining pressure.The cohesion c and the angle of internal friction  have been further analyzed,which are calculated by Hoek-Brown yield criterion.The results show that,plastic strain softening properties and volume expansion properties are displayed not only in loading,but also in unloading confining pressure,and are easier to happen suddenly under the unloading confining pressure.Moreover,by comparison and analysis of the cohesion c and the angle of internal friction  under loading and unloading confining pressure,the variation relation between rock mechanical parameters and confining pressure is obtained.The research results can provide reference for studying the mechanics and deformation characteristics of rock in underground engineering.