分幅开挖方式下高应力硬岩地下洞室的微震特性及稳定性分析
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摘要
高应力硬岩大型地下洞室开挖卸荷导致围岩片帮、塌方事故频发,严重威胁现场施工人员及设备的安全。从降低围岩局部破坏风险的角度考虑,白鹤滩水电站右岸主变室第Ⅳ层采用分幅开挖方案。通过构建微震监测系统,研究分幅开挖下岩体的微震特性及稳定性,监测结果表明:上游半幅开挖诱发的微震事件、能量大于下游半幅诱发的,且上、下游半幅开挖均表现出了掌子面贯通前微震事件、能量增大的特性,这主要受两相向掘进掌子面前方支承压力叠加的影响;上游半幅开挖诱发微震事件频发且出现了丛集现象,下游半幅开挖诱发的微震事件较少且事件空间分布离散,规律性不明显;采用Schmidt数、事件活动率与累积视体积、能量指数与累积视体积评价研究区域的稳定性,结果显示,较之于应变硬化阶段,处于应变软化阶段的岩体发生不稳定变形破坏的风险较大。研究结果可为白鹤滩水电站地下洞室施工方案的优化提供重要参考,同时也可为其他类似工程的施工提供借鉴。
Excavations of large-scale hard-rock underground caverns with high stress often result in rib spalling and collapse of surrounding rock, threatening the safety of on-site builders and equipment. From the perspective of reducing the risk of local failure of surrounding rock, framing excavation method was adopted in the fourth floor of the right transformer chamber of the Baihetan hydropower station. In order to study the microseismic(MS) characteristics and stability, MS monitoring was carried out in the right transformer chamber. The results show that: By the excavation of upstream rock, the number of MS events and energy release were greater than the downstream rock. In the process of working face advancing, the number of MS events and the energy increased, which was in accordance with the overlay abutment pressure. When the upstream rock was excavated, the excavation unloading induced seismic events and the cluster phenomenon. In contrast, the excavation of downstream rock only induced few MS events. The Schmidt number, the activity rate, the cumulative volume, and the energy index were combined to evaluate the stability of the study area. The study found that compared with the strain hardening phase, the rock mass in the stage of strain softening has a greater risk of unstable deformation and failure. The results can provide valuable reference to the optimization of construction scheme of the Baihetan hydropower station. At the same time, the results can also provide reference to other similar projects of construction.
Excavations of large-scale hard-rock underground caverns with high stress often result in rib spalling and collapse of surrounding rock, threatening the safety of on-site builders and equipment. From the perspective of reducing the risk of local failure of surrounding rock, framing excavation method was adopted in the fourth floor of the right transformer chamber of the Baihetan hydropower station. In order to study the microseismic(MS) characteristics and stability, MS monitoring was carried out in the right transformer chamber. The results show that: By the excavation of upstream rock, the number of MS events and energy release were greater than the downstream rock. In the process of working face advancing, the number of MS events and the energy increased, which was in accordance with the overlay abutment pressure. When the upstream rock was excavated, the excavation unloading induced seismic events and the cluster phenomenon. In contrast, the excavation of downstream rock only induced few MS events. The Schmidt number, the activity rate, the cumulative volume, and the energy index were combined to evaluate the stability of the study area. The study found that compared with the strain hardening phase, the rock mass in the stage of strain softening has a greater risk of unstable deformation and failure. The results can provide valuable reference to the optimization of construction scheme of the Baihetan hydropower station. At the same time, the results can also provide reference to other similar projects of construction.
引文
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[15]钱鸣高,石平五.矿山压力与岩层控制[M].徐州:中国矿业大学出版,2003.QIAN Ming-gao,SHI Ping-wu.Ground pressure and strata control[M].Xuzhou:China University of Mining and Technology Press,2003.
[16]刘国锋,冯夏庭,江权,等.白鹤滩大型地下厂房开挖围岩片帮破坏特征、规律及机制研究[J].岩石力学与工程学报,2016,35(5):865-878.LIU Guo-feng,FENG Xia-ting,JIANG Quan,et al.Failure characteristics,laws and mechanisms of rock spalling in excavation of large-scale underground powerhouse caverns in Baihetan[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(5):865-878.
[17]GIBOWICZ S J,YOUNG R P,TALEBI S,et al.Source parameters of seismic events at the underground research laboratory in Manitoba,Canada:scaling relations for events with moment magnitude smaller than-2[J].Bulletin of the Seismological Society of America,1991,81(4):1157-1182.
[18]BOATWRIGHT J,FLETCHER J B.The partition of radiated energy between P and S waves[J].Bulletin of the Seismological Society of America,1984,74:361-376.
[19]MENDECKI A J,LYNCH R A,MALOVICHKO D A.Routine seismic monitoring in mines[C]//Australian Earthquake Engineering Society 2010 Conference.Western Australia:[s.n.],2010.
[2]TEZUKA K,NIITSUMA H.Stress estimated using microseismic clusters and its relationship to the fracture system of the Hijiori hot dry rock reservoir[J].Engineering Geology,2000,56(1-2):47-62.
[3]WYSS M,BRUNE J N.Seismic moment,stress and source dimensions for earthquakes in the California-Nevada region[J].Journal of Geophysical Research,1968,73(14):4681-4694.
[4]URBANCIC T I,TRIFU C I.Recent advances in seismic monitoring technology at Canadian[J].Journal of Applied Geophysics,2000,45(4):225-237.
[5]李庶林,尹贤刚,郑文达,等.凡口铅锌矿多通道微震监测系统及其应用研究[J].岩石力学与工程学报,2005,24(12):2048-2053.LI Shu-lin,YIN Xian-gang,ZHENG Wen-da,et al.Research of multichannel microseismic monitoring system and its application to Fankou lead-zinc mine[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(12):2048-2053.
[6]唐礼忠,汪令辉,张君,等.大规模开采矿山地震视应力和变形与区域性危险地震预测[J].岩石力学与工程学报,2011,30(6):1168-1178.TANG Li-zhong,WANG Ling-hun,ZHANG Jun,et al.Seismic apparent stress and deformation in a deep mine under large-scale mining and areal hazardous seismic prediction[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(6):1168-1178.
[7]LU C P,DOU L M,ZHANG N,et al.Microseismic frequency spectrum evolutionary rule of rockburst triggered by roof fall[J].International Journal of Rock Mechanics and Mining Sciences,2013,64(6):6-16.
[8]陆菜平,窦林名,曹安业,等.深部高应力集中区域矿震活动规律研究[J].岩石力学与工程学报,2008,27(11):2302-2308.LU Cai-ping,DOU Lin-ming,CAO An-ye,et al.Research on microseismic activity rule in deep high-stress concentration district[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2302-2308.
[9]冯夏庭,陈炳瑞,明华军,等.深埋隧洞岩爆孕育规律与机制:即时型岩爆[J].岩石力学与工程学报,2012,31(3):433-444.FENG Xia-ting,CHEN Bing-rui,MING Hua-jun,et al.Evolution law and mechanism of rockbursts at deep tunnels:immediate rockburst[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(3):433-444.
[10]陈炳瑞,冯夏庭,明华军,等.深埋隧洞岩爆孕育规律与机制:时滞型岩爆[J].岩石力学与工程学报,2012,31(3):561-569.CHEN Bing-rui,FENG Xia-ting,MING Hua-jun,et al.Evolution law and mechanism of rockbursts at deep tunnels:time delayed rockburst[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(3):561-569.
[11]肖亚勋,冯夏庭,陈炳瑞,等.深埋隧洞极强岩爆段隧道掘进机半导洞掘进岩爆风险研究[J].岩土力学,2011,32(10):3111-3118.XIAO Ya-xun,FENG Xia-ting,CHEN Bing-rui,et al.Rockburst risk of tunnel boring machine part-pilot excavation in very strong rockburst section of deep hard tunnel[J].Rock and Soil Mechanics,2011,32(10):3111-3118.
[12]张伯虎,邓建辉,高明忠,等.基于微震监测的水电站地下厂房安全性评价研究[J].岩石力学与工程学报,2012,31(5):937-944.ZHANG Bo-hu,DENG Jian-hui,GAO Ming-zhong,et al.Safety evaluation research based on microseismic monitoring in underground powerhouse of hydropower station[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(5):937-944.
[13]XU N W,DAI F,LIANG Z Z,et al.The dynamic evaluation of rock slope stability considering the effects of microseismic damage[J].Rock Mechanics and Rock Engineering,2014,47(2):621-642.
[14]中国水电顾问集团华东勘测设计研究院.金沙江白鹤滩水电站地下厂房顶拱第一层及后续边墙开挖支护咨询材料[R].杭州:中国水电工程顾问集团华东勘测设计研究院,2014.Huadong Engineering Corporation Limited of Hydro China Corporation.Consulting materials on the first layer and subsequent excavation and supporting of Baihetan hydropower station,Jinsha River[R].Hangzhou:Huadong Engineering Corporation Limited of Hydro China Corporation,2014.
[15]钱鸣高,石平五.矿山压力与岩层控制[M].徐州:中国矿业大学出版,2003.QIAN Ming-gao,SHI Ping-wu.Ground pressure and strata control[M].Xuzhou:China University of Mining and Technology Press,2003.
[16]刘国锋,冯夏庭,江权,等.白鹤滩大型地下厂房开挖围岩片帮破坏特征、规律及机制研究[J].岩石力学与工程学报,2016,35(5):865-878.LIU Guo-feng,FENG Xia-ting,JIANG Quan,et al.Failure characteristics,laws and mechanisms of rock spalling in excavation of large-scale underground powerhouse caverns in Baihetan[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(5):865-878.
[17]GIBOWICZ S J,YOUNG R P,TALEBI S,et al.Source parameters of seismic events at the underground research laboratory in Manitoba,Canada:scaling relations for events with moment magnitude smaller than-2[J].Bulletin of the Seismological Society of America,1991,81(4):1157-1182.
[18]BOATWRIGHT J,FLETCHER J B.The partition of radiated energy between P and S waves[J].Bulletin of the Seismological Society of America,1984,74:361-376.
[19]MENDECKI A J,LYNCH R A,MALOVICHKO D A.Routine seismic monitoring in mines[C]//Australian Earthquake Engineering Society 2010 Conference.Western Australia:[s.n.],2010.