【摘要】 隧道工程岩爆案例表明初期支护结构体系的类型与刚度影响着破裂及微震活动的特征、机制和阶段划分,这是一个较少被探讨且亟待被揭示的问题。依托巴陕高速公路米仓山特长隧道构造碎粒岩围岩段的岩爆现象及微震监测成果,建立围岩–支护复合体系的刚度评价方法,基于震源参数指标初步探索了岩爆特征的支护体系刚度效应,揭示了刚度条件由弱变强的岩爆微震特征及演化:(1)在岩爆发育期,对围岩卸荷边界施加刚性更强的约束条件,围岩内部破裂活动趋向发生能量积累和能量转移;岩爆发育期延长,微震事件的能量、视体积类型及比重发生改变。(2)在岩爆发生期,围岩内部破裂活动趋向发生更高量值的能量释放,现场岩爆及大能量冲击灾害表现更大波及范围的特点;微震事件在短时间内迅速出现,事件率和能量率极大提升。相关研究成果可帮助认识支护结构影响下围岩破裂活动的特征、机制与阶段划分,考虑支护结构影响的围岩破坏前兆预警判据,可为科学合理的支护方式遏制岩爆风险提供实际数据和理论参考。更多还原

【Abstract】 Rockburst cases of tunnel engineering show that the type and stiffness of initial support system affect the characteristics,mechanism and stage development of fracture and microseismic activities of surrounding rock mass,which is a topic less discussed and needs to be fully revealed. Based on the rockburst phenomena and microseismic monitoring results of tectonic granulite section in the Micang mountain tunnel of Bazhong-Shanxi expressway,the evaluation method of composite stiffness by surrounding rock and support structures is proposed and the influence of support structure stiffness on the rockburst characteristics is explored based on the microseismic parameters. The evolution of rockburst characteristics with the stiffness condition changing from weak to strong is revealed as follows:(1) At the development stage of rockburst,a more rigid constraint condition is applied on the unloading boundary of surrounding rock,and the fracturing activity of surrounding rock tends to the effect of energy accumulating and energy transferring. The development period of rockburst is prolonged and the type and specific gravity of microseismic events are changing.(2) At the occurrence stage of rockburst,the fracturing activity of surrounding rock tends to produce higher energy release,and the field rockburst hazard show the characteristics of wider affected range by high energy shock. Microseismic events occur rapidly in a short time,and the event rate and energy rate are greatly increased. Finally,the research results can help to understand the characteristics,mechanism and development stages of rock fractures under the influence of support system,and to consider the influence of supporting system on the early warning criterion of surrounding rock failure. It hopes to provides practical data and theoretical reference for scientific and reasonable support ways to curb the risk of rockburst.更多还原