二长花岗岩三轴加卸载过程中声发射特征分析

为认识二长花岗岩在不同受载路径条件下破坏过程中声发射特征,通过三轴循环加卸载压缩试验和声发射试验,分析了玲珑金矿二长花岗破坏过程应力应变曲线和声发射特征参数的关系,结果表明:(1)在花岗岩的循环加卸载过程中,声发射信号主要出现在加载期的超过前一循环最大值的阶段和卸载过程的初期,弹性加载和卸载阶段后期基本无声发射现象;(2)岩石声发射活动与岩石变形破坏过程以及能量释放特征规律密切相关,在对二长花岗岩的加卸载试验的过程中,随着加卸载的进行,存在着声发射活动的活跃期和相对平静期;(3)主破裂阶段及峰后相对应力较高的时期所释放的能量要远高于卸荷阶段的初期、塑性变形的中后期这两个活跃期释放的能量,该阶段绝大部分的弹性应变能释放出来;(4)在岩石试样初期的循环加卸载过程中,岩石内部塑性破坏程度较低,Kaiser效应显著,后期的循环加卸载过程中即塑性阶段的中后期,Felicity效应显著;(5)岩石进入塑性变形的中后期,微破裂发展至破坏阶段,裂纹大量扩展、贯穿,形成宏观裂缝,弹性应变能大量释放,AE信号强烈,当达到塑性中后期的标志点时,岩石试件即到了主破裂的前夕。

Analysis on Acoustic Emission Characteristics of Monzonitic Granite during Triaxial Loading-unloading Process

Characteristics of acoustic emission in the failure process of the monzonite granite under different loading paths,triaxial cycle load-unload experiment and acoustic emission (AE) test were carried out.Relationship between stress strain curve and AE parameters were analyzed.Some results are achieved,(1) during cyclic loading and unloading process of granite,AE signals mainly emerge in the stage of the maximum loading period exceeded in pre-cyclic loading and the initial process of unloading.However,AE signals cannot be found in the elastic loading and unloading stage.(2) Acoustic emission of rock is closely related to the deformation and failure process of rock and the characteristics of energy release.The active phase and relatively quiet period of the acoustic emission phenomenon can be found in the process of loading and unloading tests of monzonite granite.(3) Energy released in the main failure stage and the relative stress during the peak is much higher than that in the initial stage of unloading and the middle and later stage of plastic deformation,most of the elastic strain energy are released in this stage.(4) During the initial loading and unloading process,the plastic damage of rock is lower,Kaiser effect is obvious,and in the middle and later stage of plastic deformation,Felicity effect is obvious.(5) In the middle and late stages of plastic deformation,a large number of cracks develop,extend,and form into macro cracks,the elastic strain energy is released,the AE signal is strong,when it reaches the mark of the middle and late stage of plasticity,the rock specimen is in the eve of main failure.