不同循环加载应力下花岗岩Kaiser效应特征的试验研究

为了更准确地获取花岗岩的Kaiser效应点对应的应力值σAE,利用RMT-100B岩石力学伺服试验机和Micro-Ⅱ Express型声发射监测系统,研究不同循环加载应力σci下岩石Kaiser效应特征.结果表明:相比单次加载,在循环加载作用下,试样的应力-应变曲线在加载初期下凸减弱,压密阶段变短;由于试样的加卸载曲线...

Experimental study on Kaiser effect characteristics of granite under different cyclic loading stresses

In order to obtain the stress valueσA E corresponding to the Kaiser effect point of granite more accurately,the influences of different cyclic loading stressσⁱ_con the Kaiser effect characteristics are studied by the RMT-100Brock mechanics servo testing machine and the Micro-ⅡExpress acoustic emission monitoring system.The results show that,under the cyclic loading the stress-strain curve of the specimen becomes less convex at the initial loading stage and shorter at the compaction stage,in comparison with that under the single loading.Whenσⁱ_c<σm,the frictional acoustic emission is effectively weakened,conducive to the identification of Kaiser effect points in the subsequent loading process.Whenσⁱ_c>σm,the cumulative ringing count curve rises in steps,the extension of cracks and the initiation of new cracks occur inside the rocks,and the cyclic stress becomes a new memory stress.Whenσⁱ_c<σm,the Felicity ratio is less than 1.Otherwise it is more than 1.Therefore,in the in-situ stress test,a cyclic loading and unloading method with low stress and small gradient can be adopted,and the effective stress interval of the Kaiser effect can be screened by the Felicity ratio,reducing the recognition range of the Kaiser effect point and improving the accuracy of the in-situ stress measurement.