高应力硬岩卸荷岩爆模式及损伤演化分析

Pattern and damage evolution of unloading rockburst for high-stress hard rock

针对岩爆形成机制研究的不足,结合岩爆实例和真三轴加、卸荷试验,分析了卸荷岩爆模式,建立了围岩卸荷岩爆发生劈裂破坏和剪切破坏的损伤变量表达式,即损伤演化方程。结果表明,岩爆破裂演化表现为劈裂和剪切的复合破坏形式,不同之处只是劈裂和剪切哪一个所占的成分更大而已;随着剪切成分的增大,爆坑由呈现平底到弧形甚至三角形或V形;随着应力的增加,岩爆倾向性围岩有一段时间的平静期(无损伤),具体平静期存在时间的长短与围岩卸荷前后的应力水平有关,损伤一旦开始则加速度明显,具有较强的临界敏感性;劈裂总是优先发生的,围岩卸荷后的应力水平越高含剪切成分越大,岩爆也越强烈。

Aiming at the formation mechanism of rockburst, the unloading rockburst mode were analyzed by rockburst examples and true triaxial loading and unloading test. The damage evolution equation of splitting failure and shearing failure of surrounding rock unloading rockburst were established. The results show that the fracture evolution of rockburst represent the composite destroying forms of splitting failure and shearing failure, just the difference depends on the size of the respective components： along with the increase of shearing components, blasting pit present the changes from flat bottom to arc so much as triangle or v shape; along with the increase of stress, surrounding rock has a quiet periods （no damage） and damage acceleration is obvious, once damage begin and rock with rockburst tendency has strong critical sensitivity; splitting failure always occurs preferentially; and the containing shearing composition becomes greater as the surrounding rock stress level after unloading becomes higher; and the rockburst intensity also becomes stronger.