摘要
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-ⅡExpress型声发射监测系统,研究不同循环加载应力σ^(i)_(c)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不能重合而形成的滞回环,随着循环次数和循环应力水平的增大,朝着应变增大的方向移动;当σ^(i)_(c)<先期最大应力σm时,摩擦型声发射现象被有效地减弱,这有利于后续加载过程中Kaiser效应点的识别;当σ^(i)_(c)>σm时,振铃累计计数曲线呈台阶状上升,岩石内部发生裂纹的扩展或新裂纹的孕育,该循环应力成为新的记忆应力。当σ^(i)_(c)<σm时,Felicity比小于1,反之大于1,因此,在地应力测试中,可以采用低应力、小梯度的循环加卸载方式,并结合Felicity比,进而缩小Kaiser效应点的识别范围,提高地应力测量精度。
In order to obtain the stress valueσA E corresponding to the Kaiser effect point of granite more accurately,the influences of different cyclic loading stressσ^(i)_(c)on 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.Whenσ^(i)_(c)<σm,the frictional acoustic emission is effectively weakened,conducive to the identification of Kaiser effect points in the subsequent loading process.Whenσ^(i)_(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.Whenσ^(i)_(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.
作者
张延新
曹龙辉
李泽杰
陈天星
ZHANG Yanxin;CAO Longhui;LI Zejie;CHEN Tianxing(College of Civil Engineering&Mechanics,Yanshan University,Qinhuangdao 066004,Hebei,China;Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province,Yanshan University,Qinhuangdao 066004,Hebei,China)
出处
《实验力学》
CSCD
北大核心
2021年第1期123-132,共10页
Journal of Experimental Mechanics
