岩体崩塌的早期预警方法与试验验证

Early-warning method of rock collapse and its experimental verification

岩块体崩塌的早期预警一直是岩土工程灾害研究的热点和难点问题。传统监测方法大多关注于破坏阶段,因此很难实现崩塌等脆性破坏灾害的早期预警。实际上,崩塌通常经历分离和破坏两个阶段。关注分离破坏阶段的前兆事件,可更快提醒公众在灾难性的崩塌事件之前寻求庇护。本次实验应用激光多普勒测振技术,通过新型物理模型实验,开展危岩分离破坏前兆现象识别研究。实验采取新型的冰冻实验方法来模拟岩块体黏结强度不断降低,块体随着时间推移,稳定性不断降低,最终于117 s发生破坏。监测结果显示,频率监测指标分别在50 s和115 s发生分离和加速破坏前兆。基于分离阶段破坏前兆识别提前67 s实现预警,而基于加速破坏阶段的破坏前兆识别则在破坏前2 s触发预警。相较于传统的基于破坏前兆识别的预警思路,基于分离破坏前兆识别的预警方法提前65 s对岩块体崩塌破坏进行预警,具有更好的时效性,可有效利用早期预警的“黄金期”,为工程中更好地应对崩塌灾害争取时间。基于分离破坏前兆识别的岩块体崩塌灾害预警思路是矿山等高陡边坡岩体崩塌等脆性破坏灾害应急预防的发展方向。

Early warning of rock collapse has been one of the frontier problems in the study of geological hazards for many years.The traditional monitoring methods pay more attention to failure phase,and it is difficult to realize the early warning of brittle failure such as rock collapse.In fact,the collapse generally undergoes two phases,which are separation phase and failure phase.Focusing on the precursory events of the separation phase can quickly alert the public in time to seek shelter before a devastating rock collapse.Based on the Laser Doppler vibration testing technology and new physical model experiment,the study focused on the identification of failure precursors of unstable rock in the separation phase.In this experiment,a new freezing experiment method was adopted to simulate the continuous decrease of the bond strength of rock block,and the stability of the block continued to decrease as time went by,and finally broke down at 117 s.The monitoring results showed that the separation precursor occurred at 50 s and the accelerated failure precursor occurred at 115 s,respectively.The early warning based on the identification of failure precursor in the separation phase was triggered 67 seconds before the destruction,while the early warning based on the identification of failure precursor in the accelerated failure phase was 2 seconds.Compared with the traditional early-warning idea based on the recognition of failure precursor,the early-warning method based on the separation failure precursor used for early warning of rock block collapse created 65 s in advance,which has better timeliness and can effectively be used as“golden period”of early warning to buy time for better coping with collapse disasters in the projects.The idea of early warning of rock mass collapse disaster based on separation failure precursor recognition is the development direction of emergency prevention of brittle failure disasters such as rock mass collapse of high and steep slopes in mines.