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围岩浅部发生的爆裂松脱、片状剥落、有声响、岩片弹射等岩爆现象,多属于劈裂破坏机制.针对硬脆完整围岩浅部的劈裂岩爆现象,采用辉长岩试样,进行真三轴加卸载试验,真实模拟实际围岩的应力演化并且实现了小主应力方向的单面卸载.为便于对比分析,同时进行了双轴压缩试验,最后根据试验结果分析了卸荷劈裂岩爆机理.两种试验方法均得到了不同程度的劈裂岩爆现象,但卸荷岩样发生劈裂岩爆所需的大主应力比双轴压缩试验下的要小很多;两者的劈裂岩爆范围不同,卸荷劈裂岩爆均产生在卸荷面附近区域,这与实际的岩爆情况一致;中间主应力对围岩发生劈裂及劈裂程度起重要作用;研究结果为分析劈裂岩爆发生条件和劈裂岩爆机理以及工程预测预报提供依据.
Rock burst occurred in the shallow part of surrounding rock, flaking, sounding, rock ejection and other rock burst phenomena are mostly splitting failure mechanism.Aiming at the phenomenon of splitting rock burst in the shallow part of the surrounding rock, the gabbro Sample, the true triaxial unloading test was carried out to simulate the real stress evolution of the surrounding rock and to realize the unilateral unloading of the direction of the small principal stress.In order to facilitate the comparative analysis, the biaxial compression test was carried out at the same time. According to the experimental results, Unloading and splitting rockburst mechanism.The fracturing rockburst has been obtained in both test methods to different degrees, but the principal principal stress required for fracturing rock burst in unloading rock specimen is much smaller than that under biaxial compression test ; The range of the split rock burst is different, and the unloading split rock burst occurs in the area near the unloading surface, which is consistent with the actual rock burst; the intermediate principal stress plays an important role in the occurrence and splitting of the surrounding rock The results provide the basis for the analysis of the occurrence conditions of splitting rock burst and the mechanism of split rock burst and the prediction of engineering.