开挖强卸荷下柱状节理岩体时效破裂过程协同观测与机制分析  

Synergistic observation and mechanism analysis of time-dependent fracture process of columnar jointed rockmass under strong unloading during excavation

作　　者：丰光亮[1] 张建聪 江权[1] 李邵军[1] 肖亚勋[1] 姚志宾 FENG Guangliang;ZHANGJiancong;JIANG Quan;LIShaojun;XIAOYaxun;YAO Zhibin(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071 China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang,Liaoning 110819,China)

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]中国科学院大学,北京100049 [3]东北大学,深部金属矿山安全开采教育部重点实验室,辽宁沈阳110819

出　　处：《岩石力学与工程学报》2021年第S02期3041-3051,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41972295,U1965205)。

摘　　要：作为一种含规则结构面网络结构的密集节理岩体,高应力下柱状节理岩体具有节理面张开、岩块破裂、岩体结构松弛等复杂力学响应过程。依托白鹤滩水电站左岸3"导流洞,开展实时破裂微震监测、松弛深度声波测试和裂隙可视化钻孔摄像协同观测,多角度分析开挖强卸荷下柱状节理岩体时效破裂过程与机制。研究结果表明:在时间上,柱状节理岩体时效破裂过程持续10d以上,时效破裂微震事件随开挖后天数增加呈对数型函数减少的规律,其过程分为减弱期、稳定期和微弱期3个阶段:在空间上,柱状节理岩体时效破裂呈与掌子面距离增加及随距边墙深度增加而减少的特征,时效破裂微震事件集中在边墙3m范围内,松弛深度也在3m左右,可视裂隙分布在2.5 m范围内,三者具有空间一致性;开挖尺寸和位置对柱状节理岩体时效破裂有显著影响,半断面分步,开挖产生的时效破裂微震事件少于一次性全断面;柱状节理岩体破裂类型以张拉为主,掌子面后30 m外仍发生,不少时效张拉破裂。研究结果可为高应力下密集节理岩体的支护优化和安全施工提供借鉴。As a kind of dense jointed rockmass with regular structure plane network,columnar jointed rockmass is with complex mechanical response processes under high stress,such as jointed plane opening,rock block rupture and rockmass structural relaxation.Based on the engineering background of the#3 diversion tunnel on the left bank of Baihetan hydropower station,time-dependent fracture process of columnar jointed rockmass under strong unloading during excavation and its mechanism were studied after with a series of synergistic observation.The synergistic observation contains microseismic monitoring,acoustic velocity test and digital borehole camera test.Results show that the period of time-dependent fracture process is more than 10 days.The number of time-dependent fractures decreases with the increasing of days after excavation.It is a logarithmic function and can be divided into three time-dependent stages:weakening period,stable period and weak period.The number of time-dependent fractures decreases with the increasing of distance from the working face,and with the increasing of depth from the side wall.The time-dependent fractures are mainly within 3 m from the side wall,the relaxation depth is about 3 m,and the visible fractures are distributed within 2.5 m.The synergistic observation results have a good spatial consistency.The excavation size and location have significant effect on the time-dependent fractures of columnar jointed rockmass.The number of time-dependent microseismic events generated by step-by-step excavation of half section is less than that of the full section.Tensile fracture is the main fracture type of columnar jointed rockmass and there are a lot of time-dependent tensile fractures beyond 30 m behind the working face.The research results can provide reference for support optimization and safe construction of dense jointed rockmass under high stress.

关 键 词：岩石力学 柱状节理 时效破裂 机制 微震 协同观测 白鹤滩水电站 

分 类 号：TU451[建筑科学—岩土工程]