深埋隧洞岩爆孕育规律与机制:即时型岩爆

摘要

论述深埋隧洞岩爆孕育过程的现场原位综合观测试验思路和方法,给出利用该方法观测到的岩爆孕育时空演化规律以及基于观测结果的关于岩爆孕育机制的认知成果.通过一系列现场深埋隧洞开挖过程中的多元信息综合观测试验,揭示深埋隧洞的即时型岩爆(隧洞开挖卸荷效应影响过程中的隧洞掌子面及其附近的围岩,开挖后几小时到几天内发生)的裂纹(萌生、扩展、张开和闭合过程)、变形、弹性波、声发射和微震时空演化规德及其在时空上的分布特征.通过对监测的微震信息进行矩张量分析,认识即时型岩爆中应变型和应变-结构面滑移型2类岩爆的孕育机制差异性:前者主要是拉张破裂引起,后者主要是拉张破坏、剪切破裂与拉剪-压剪破裂引起,剪切破裂主要沿着硬性结构面发生,形成爆坑边界.该研究成果为针对时空演化规律的深埋隧洞岩爆的预测和动态调控提供了重要基础.%The ideas and methodology for the in situ monitoring of rockburst preparation of deep tunnels was described firstly. The time and space evolution law of immediate rockburst observed, which occurred usually during or after excavation immediately and affected mainly by excavation unloading effectiveness, was analyzed. Based on a series of in situ monitoring of deep tunnels, process of crack initiation, propagation, opening and closing, evolution of wave velocity, deformation, acoustic emission and microseismicity were observed. Based on moment tensor analysis of the monitored microseismicity during the excavation of deep runnels, the difference of mechanism of strain rockburst and strain-structure slip rockburst was found. The former was mainly from tensile cracking but the latter mainly from tensile cracking, shear cracking, and tensile-shear/compressive shear cracking which was from shearing of stiff structures and formed boundary of rockburst pit. The results are used as a guide of prediction of rockburst and its dynamic control based on evolution of the monitored microseismicity and other information.