巷道岩爆过程能量演化特征实验研究

Experimental study on energy evolution characteristics in the process of tunnel rockbursts

开展双轴加载条件下巷道岩爆声发射监测实验,分析巷道岩爆过程宏观破坏特征,并与现场岩爆发生过程进行对比研究;借助声发射能量参数,分析岩爆宏观破坏过程能量积聚、释放规律及能量的时间效应,重点探讨水平载荷对岩爆过程能量演化规律的影响,进一步从能量的角度揭示巷道岩爆的发生机制。研究结果表明:巷道岩爆存在平静期、颗粒弹射、岩片剥落伴随颗粒弹射、爆裂喷射4个典型阶段特征,但在颗粒弹射、片状剥离现象后会出现"短暂平静期",即巷道岩爆经历了平静期→颗粒弹射→短暂平静期→岩片剥落伴随颗粒弹射→短暂平静期→爆裂喷射的演化过程。巷道岩爆过程平静期对应能量的积聚过程,颗粒弹射、岩片剥离伴随颗粒弹射和剧烈喷射对应能量的释放过程,而"短暂平静期"内能量发生机制与水平载荷有关。一方面,水平载荷增大,岩爆孕育过程积聚的能量显著增加,为岩爆发生提供了足够的动力源;另一方面,水平载荷增大,"短暂平静期"内能量由积聚过程逐渐转变为释放过程,导致颗粒弹射到剧烈喷射阶段能量持续释放,且能量释放速度加快;上述两方面的综合作用致使高水平载荷下岩爆孕育过程聚集的大量能量在短时间内快速释放,从而诱发突发性强、破坏性大的岩爆灾害,同时预测的难度也加大。

The acoustic emission monitoring experiment of tunnel rockbursts under biaxial loading was carried out.Compared with the process of rockbursts in practical engineering,the macroscopic damage characteristics of tunnel rockburst process was analysed.With the help of acoustic emission energy parameters,the energy accumulation and release law and the time effect of energy during the macro-failure process of rockbursts were analysed.The influence of the horizontal load on the energy evolution law of rockburst process was discussed,and the mechanism of rockbursts was revealed from the point of energy.The results show that roadway rockbursts have four typical stages including quiet period,particle ejection,rock fragmentation accompanied by particle ejection and burst ejection,and that there will be a short quiet period after particle ejection or flake exfoliation.That is to say,rockbursts experience an evolution process of calm period,particle ejection,short calm period,rock fragmentation accompanied by particle ejection,short calm period and burst ejection.The calm period corresponds to the process of energy aggregation,while the other three typical stages correspond to the process of energy release.The energy generation mechanism in the short quiet period is related to the horizontal load.On one hand,with increasing the horizontal load,the accumulated energy increases significantly in the process of rockburst incubation,which provides enough power source for the occurrence of the rockburst.On the other hand,the energy in the short quiet period gradually changes from the aggregation process to the release process,which leads to a continuous and quick energy release in the process from particle ejection to intense ejection.Under the combined action of the above two aspects,a large amount of energy accumulated in the process of rockburst incubation under a high-level load is released rapidly in a short time,leading to a sudden strong and destructive rockburst disaster which is difficult to predict.