真三轴单面临空花岗岩岩爆自组织临界特征研究

Study on Self-organized Critical Characteristics of True Rriaxial Single-face Empty Granite Rockburst

为探究不同应力状态下花岗岩岩爆失稳特征,开展真三轴单面临空岩爆试验,结合声发射监测系统,根据自组织临界理论,分析岩爆过程应力变化及声发射能量序列的时间属性和定位信息的空间属性。试验结果表明:将岩爆自组织过程分解为时间线与空间线,最大程度地实现了岩爆自组织过程的可视化及岩体状态的量化,且能量时域性通过了幂律特征的验证,具有较强自相似性;岩爆孕育过程第二阶段的临界指数相对第一阶段较大,说明岩爆发生的概率随着自组织演化加剧;岩爆自组织行为存在中间主应力效应,随着中间主应力增大对岩石破裂限制作用增强,临界点出现越晚,临界指数越大,同时高中间主应力下亚临界点至临界点的平静期较长,自组织行为较弱,易诱发突发性强、破坏性大的岩爆灾变,预测难度增加。本研究结果为精确预测岩石岩爆提供了更为前沿、完善的思路。

In order to explore the instability characteristics of granite rock burst under different stress states,the true tri-axial single-faced empty rock burst test was carried out.Combined with the acoustic emission monitoring system,according to the self-organized criticality theory,the stress change during the rock burst process and the time attribute of the acoustic emis-sion energy sequence and the spatial attribute of the positioning information were analyzed.The experimental results show that the self-organizing process of rockburst is decomposed into time line and space line,which realizes the visualization of self-or-ganizing process of rockburst and the quantification of rock mass state to the greatest extent,and the energy time domain is veri-fied by power law characteristics,which has strong self-similarity.The critical index of the second stage of rockburst is larger than that of the first stage,indicating that the probability of rockburst increases with the evolution of self-organization.The self-organization behavior of rock burst has the effect of intermediate principal stress.With the increase of intermediate principal stress,the limiting effect on rock fracture is enhanced.The later the critical point appears,the larger the critical index is.At the same time,the quiet period from sub-critical point to critical point under high intermediate principal stress is longer,and the self-organization behavior is weaker.It is easy to induce sudden and destructive rock burst disasters,and the difficulty of pre-diction is increased.The results of this study provide a more advanced and perfect idea for accurately predicting rock burst.