岩爆弹射破坏过程的试验研究

 利用自主研发的真三轴岩爆刚性试验机，对粗晶粒花岗岩试件开展应变型岩爆弹射破坏过程试验研究。设计不同的加载与卸载路径，模拟能量集聚驱动型与应力集中驱动型2类岩爆的弹射破坏过程，在借助高速摄像系统对岩石碎块弹射过程进行影像记录与速度测量的基础上，分析岩爆弹射破坏过程的特征与规律。研究结果表明：(1) 岩爆弹射破坏过程可概括为颗粒弹射、劈裂成板、剪切成块、板折弹射4个阶段；(2) 弹射破坏后的岩样母体具有二元破坏形态，即临空面出现V形或台阶状的岩爆坑，而岩身内侧出现贯穿性剪切裂缝；(3) 加载速率对应力集中驱动型岩爆具有重要影响，在0.05～2 MPa/s加载速率范围内，弹射动能随加载速率增大而增大；(4) 峰前集聚的弹性应变能足够大且能量输入速率足够大是岩样发生应力集中驱动型岩爆的基本条件；(5) 无论是能量集聚驱动型岩爆，还是应力集中驱动型岩爆，弹射动能占岩样峰前可释放弹性应变能的比例不足1%。

Experimental study of ejection process in rockburst

Experimental study on the ejection process of strain rockburst in coarse-grain granite using the rigid true-triaxial test machine for rockburst developed in house was presented. The processes of ejecting failure in focused energy driven rockburst and in concentrated stress driven rockburst were respectively simulated with different loading and unloading paths. The speed of rock fragments was recorded with the high speed camera system and the characteristics of rockburst were analyzed. Rockburst was found to have four typical stages such as small grain ejections，spalling，shearing rock into fragments and fragments ejection. The failure of the specimen after rockburst had a V-shaped notch or sidestep-shaped notch near the free face and a shear zone away from the free face. Loading rate had important influence on the concentrated stress driven rockburst. The kinetic energy had an increasing trend with the increasing of loading rate ranging from 0.05 MPa/s to 2 MPa/s. Gathering enough elastic strain energy and inputting energy with enough high rate in the pre-peak are essential conditions for stress concentration driven rockbust. Whether it is the focused energy driven rockburst or the concentrated stress driven rockburst，less than 1% of released elastic strain energy in the pre-peak was translated into the kinetic energy.