深埋隧洞岩爆孕育规律与机制:时滞型岩爆  

EVOLUTION LAW AND MECHANISM OF ROCKBURST IN DEEP TUNNEL:TIME DELAYED ROCKBURST

作　　者：陈炳瑞[1] 冯夏庭[1] 明华军[1] 周辉[1] 曾雄辉[2] 丰光亮[1] 肖亚勋[1] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]二滩水电开发有限责任公司,四川成都610051

出　　处：《岩石力学与工程学报》2012年第3期561-569,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点基础研究发展计划(973)项目(2010CB732006);国家自然科学基金资助项目(50909092);湖北省自然科学基金项目(2009CDB120)

摘　　要：根据锦屏II级水电站引水隧洞现场岩爆发生机制,提出时滞型岩爆概念,并对时滞型岩爆进行系统研究,发现:(1)时滞型岩爆一般发生在隧洞掌子面开挖应力调整扰动范围之外,是岩爆区开挖应力调整与外界扰动联合作用的结果。80%的时滞型岩爆时间上滞后该区开挖时间6～30 d,空间上在距离掌子面80 m的范围内。(2)时滞型岩爆区,一般节理、裂隙、夹层等原生结构面比较丰富,结构面类型以与洞轴线成小夹角的隐性结构面为主。(3)时滞型岩爆区开挖时,应力调整剧烈,围岩的破裂活动较频繁,微震事件时间上持续增加,空间上位置集中;视体积持续增加,有突增趋势;能量指数持续高位,有下降趋势;岩爆发生前夕,微震事件较少,存在一个明显的"平静期",且岩爆发生时视体积和能量指数变化不明显。(4)时滞型岩爆区开挖卸荷后,初期微震事件以拉伸、剪切及拉剪混合型破坏为主;接着,以沿破坏面扩展的拉伸破坏为主;随后,有一个明显的"平静期";最后岩爆发生时,以剪切破坏为主导。根据时滞型岩爆的特征、演化规律与机制,建议时滞型岩爆应采取"减少扰动,先喷,再锚,紧挂网,紧复喷"的联防策略。The time delayed rockburst（TDR） is named based on mechanism and characteristic of rockburst occurring in the diversion tunnels of Jinping II hydropower station;and then it is analyzed and investigated systematically in terms of microseismic and rockburst data in situ.The conclusions are acquired as following：（1） Stress adjusting after rockburst zone is excavated and disturbing outside of stress adjusting range of rockburst zone work together results in the TDR bursting out.80% of TDR occur from 6 to 30 d after the rockburst zone is excavated and inside of 80 m ranges from tunnel face.（2） All kinds of structural planes,such as joint,fracture,weak intercalation and so on,are main characteristic of surrounding rockmass in rockburst zone,the strike of structure plane is parallel or has a small angle with the axial of the tunnel.（3） As the rockburst zone is excavated,the magnitude and rate of stress adjusting is very large;fracture frequency of surrounding rockmass is quite high;and the microseismic events are located at the same zone in three-dimension space and its number increases continuously with time.Apparent volume of surrounding rock mass has a sudden increasing trend.Energy index has a sudden drop trend in the same time.Before the TDR burst out,microseismic activity has an obviously ＂sleep＂ period and the changes of apparent volume and energy index of surrounding rock mass are not very obvious.（4） The tensile,shear and mixed fracture all live during process of rockburst zone excavated.Then the fracture along the structure plane is main trend and tensile fracture is main fracture form.At last,the shear failure is main as the rockburst occurring.A union prevention scheme that firstly the concrete layer with steel fibre is built in time;secondly,the rock bolts are constructed;thirdly,the steel mesh is connected to the surrounding rockmass;lastly,the concrete with steel fibre is built again,which is proposed for TDR,based on the evolution characteristic,law and mechanism of TDR.

关 键 词：岩石力学 深埋隧洞 时滞型岩爆 微震 破坏机制 能量指数 锦屏II级水电站 

分 类 号：TU45[建筑科学—岩土工程]