巨型地下洞室脆性围岩高应力破裂防治措施研究
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摘要
脆性岩体高应力破裂是西部水电地下工程面临的主要岩石力学问题之一。依托世界最大规模的白鹤滩地下厂房洞室群,在概括高应力条件和玄武岩脆性特征基础上,说明了地下洞室围岩破裂破坏形式。采用3DEC中围岩能量释放等指标,研究了洞群布置、体形优化等宏观策略;依据围岩高应力集中特征,分析了开挖程序和支护时机等应对措施。结果表明,针对构造应力占主导的地下工程,可研设计应尽可能使主要洞室轴线与σ01小角度相交、宜选择双向成拱的圆筒形体形、保证顶拱曲率与应力拱相适应,并且,在施工期应尽可能沿σ01方向优先开挖、对应力集中的顶拱开挖不宜过多分幅、河谷应力条件下应优先开挖临江侧,此外,必须充分利用掌子面效应及时支护,抑制脆性岩体破裂扩展和时效变形。工程实践表明,防治脆性围岩高应力破裂的战略性措施能够降低洞室群围岩产生破裂破坏的总体风险,而战术性措施能够减小支护代价,提升工程安全性和经济合理性。
The high stress inducing fracture of brittle rock mass is one of the major rock mechanics problems in western hydropower project. Relying on the world's largest underground powerhouse caverns,on the basis of the high in-situ stress condition and the brittle characteristics of basalt,the fracture failure mode of the caverns is explained.Using the index of energy release of surrounding rock in 3 DEC,the macro strategies such as caverns layout and shape optimization were studied. According to the characteristics of high stress concentration in surrounding rock,the countermeasures of excavation procedure and supporting time were analyzed. Results show that for the underground engineering affected by high tectonic stress,in the feasibility study phase,the main caverns axis should be as far as possible intersects with σ01 at small angle,the cylindrical shape with the bidirectional arch should be adopted,and the curvature of the crown should be suitable to the stress arch. Moreover,in the construction period,the priority excavation direction should be along σ01,the excavate steps of arch with stress concentration should not be too much,and the river side of tunnel with river valley stress conditions should be priority excavated. In addition,it is necessary to make full use of the tunnel face effect to support timely and restrain the fracture extension and time-depend deformation of brittle rock mass. Engineering practice shows the strategic measures to prevent the high stress rupture of brittle rock can reduce the overall risk of the surrounding rock in the cavern,and tactical measures can reduce support cost,and improve construction safety and economic rationality.
The high stress inducing fracture of brittle rock mass is one of the major rock mechanics problems in western hydropower project. Relying on the world's largest underground powerhouse caverns,on the basis of the high in-situ stress condition and the brittle characteristics of basalt,the fracture failure mode of the caverns is explained.Using the index of energy release of surrounding rock in 3 DEC,the macro strategies such as caverns layout and shape optimization were studied. According to the characteristics of high stress concentration in surrounding rock,the countermeasures of excavation procedure and supporting time were analyzed. Results show that for the underground engineering affected by high tectonic stress,in the feasibility study phase,the main caverns axis should be as far as possible intersects with σ01 at small angle,the cylindrical shape with the bidirectional arch should be adopted,and the curvature of the crown should be suitable to the stress arch. Moreover,in the construction period,the priority excavation direction should be along σ01,the excavate steps of arch with stress concentration should not be too much,and the river side of tunnel with river valley stress conditions should be priority excavated. In addition,it is necessary to make full use of the tunnel face effect to support timely and restrain the fracture extension and time-depend deformation of brittle rock mass. Engineering practice shows the strategic measures to prevent the high stress rupture of brittle rock can reduce the overall risk of the surrounding rock in the cavern,and tactical measures can reduce support cost,and improve construction safety and economic rationality.
引文
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[18]王卫军,袁超,余伟健,等.深部高应力巷道围岩预留变形控制技术[J].煤炭学报,2016,41(9):2157-2164.(Wang Weijun,Yuan Chao,Yu Weijian,et al.Control technology of reserved surrounding rock deformation in deep roadway under high stress[J].Journal of China Coal Society,2016,41(9):2157-2164.(in Chinese))
[19]向欣,王义锋,孟国涛,等.大跨度地下洞室拱顶稳定性及支护措施研究[J].岩石力学与工程学报,2012,31(增2):3643-3649.(Xiang Xin,Wang Yifeng,Meng Guotao,et al.Study of stability and supporting measures of chamber arch crown for large span underground caverns[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Supp.2):3643-3649.(in Chinese)).
[2]王仁坤,邢万波,杨云浩,等.水电站地下厂房超大洞室群建设技术综述[J].水力发电学报,2016,35(8):1-11.(Wang Renkun,Xing Wanbo,Yang Yunhao,et al.Review on construction technologies of large-scale underground caverns in hydropower stations in China[J].Journal of Hydroelectric Engineering,2016,35(8):1-11.(in Chinese))
[3]张勇,肖平西,丁秀丽,等.高地应力条件下地下厂房洞室群围岩的变形破坏特征及对策研究[J].岩石力学与工程学报,2012,31(2):228-244.(Zhang Yong,Xiao Pingxi,Ding Xiuli,et al.Study of deformation and failure characteristics for surrounding rocks of underground powerhouse caverns under high geostress condition and countermeasures[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(2):228-244.(in Chinese))
[4]戴峰,李彪,徐奴文,等.猴子岩水电站深埋地下厂房开挖损伤区特征分析[J].岩石力学与工程学报,2015,34(4):735-744.(Dai Feng,Li Biao,Xu Nuwen,et al.Characteristics of damaged zones due to excavation in deep underground powerhouse at Houziyan hydropower station[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(4):735-744.(in Chinese))
[5]马行东.官地电站高应力大跨度洞室群围岩稳定性评价[J].地下空间与工程学报,2016,12(增2):564-570.(Ma Xingdong.Surrounding rock stability evaluation of large span cavern group with high stress of Guandi hydropower station[J].Chinese Journal of Underground Space and Engineering,2016,12(Supp.2):564-570.(in Chinese))
[6]江权,冯夏庭,陈国庆,等.高地应力条件下大型地下洞室群稳定性综合研究[J].岩石力学与工程学报,2008,27(增2):3768-3777.(Jiang Quan,Feng Xiating,Chen Guoqing,et al.Stability study of large underground caverns under high geostress[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(Supp.2):3768-3777.(in Chinese))
[7]孟国涛,樊义林,江亚丽,等.白鹤滩水电站巨型地下洞室群关键岩石力学问题与工程对策研究[J].岩石力学与工程,2016,35(12):2549-2560.(Meng Guotao,Fan Yilin,Jiang Yali,et al.Key rock mechanical problems and measures for huge caverns of Baihetan hydropower plant[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(12):2549-2560.(in Chinese))
[8]张春生,陈祥荣,侯靖,等.锦屏二级水电站深埋大理岩力学特性研究[J].岩石力学与工程学报,2010,29(10):1999-2009.(Zhang Chunsheng,Chen Xiangrong,Hou Jing,et al.Study of mechanical behavior of deep-buried marble at Jinping II Hydropower Station[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(10):1999-2009.(in Chinese))
[9]Martin C D,Kaiser P K,Christianansson R.Stress,instability and design of underground excavations[J].International Journal of Rock Mechanics and Mining Sciences,2003,40(7):1027-1047.
[10]Martin C D,Maybee W G.The strength of hard-rock pillars[J].International Journal of Rock Mechanics and Mining Sciences,2000,37(8):1239-1246.
[11]朱焕春,褚卫江,朱永生,等.西部地下工程关键问题与工作方法之二:岩体特性与工程设计[A]∥中国水电地下工程建设与关键技术论文集[C].北京:中国水利水电出版社,2012:31-42.(Zhu Huanchu,Chu Weijiang,Zhu Yongsheng,et al.The key problem in underground engineering and working method:part 2-Characteristics of rock mass and engineering design[A]∥China Hydropower Underground Engineering Construction and Key Technologies[C].Beijing:China Water Power Press,2012:31-42.(in Chinese))
[12]Jiang Y L,Xu J Q,Meng G T.Numerical evaluation of cavern layout design for the baihetan hydropower project in china[A]∥44th U.S.Rock Mechanics/Geomechanics Symposium[C].Houston:ARMA,2011:119-215.
[13]Itasca Consulting Group Inc.3DEC(3 dimensional distinct element code)user&s manual version 5.0[M].Minneapolis,2013.
[14]张勇,肖平西,程丽娟,等.基于岩石强度应力比的大型地下洞室群布置设计方法[J].岩石力学与工程学报,2014,33(11):2314-2331.(Zhang Yong,Xiao Pingxi,Ding Xiuli,et al.Method of layout design based on ratio of rock strength to in-situ stress for large underground caverns[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(11):2314-2331.(in Chinese))
[15]孟国涛,吕慷,陈益民,等.高应力条件下巨型地下洞室穹顶施工方案比较[J].科技通报,2017,33(1):205-211.(Meng Guotao,LüKang,Chen Yimin,et al.Comparison of excavating scheme for giant underground cavern dome under high stress conditions[J].Bulletin of Science and Technology,2017,33(1):205-211.(in Chinese))
[16]Itasca Consulting Group Inc.FLAC3D(Fast lagrangian analysis of continua in 3 dimensions)user’s manual version 5.01[M].Minneapolis,2013.
[17]孟国涛,吴家耀,陈平志,等.白鹤滩水电站左右岸地下厂房洞室群第I~VIII期监测反馈分析[R].杭州:浙江中科依泰斯卡岩石工程研发有限公司,2017.(Meng Guotao,Wu Jiayao,Chen Pinzhi,et al.I~VIII period monitoring feedback analysis for the underground powerhouse caverns of Baihetan hydropower station[R].Hangzhou:Hydro China ITASCA R&DCenter Co.Ltd.,2017.(in Chinese))
[18]王卫军,袁超,余伟健,等.深部高应力巷道围岩预留变形控制技术[J].煤炭学报,2016,41(9):2157-2164.(Wang Weijun,Yuan Chao,Yu Weijian,et al.Control technology of reserved surrounding rock deformation in deep roadway under high stress[J].Journal of China Coal Society,2016,41(9):2157-2164.(in Chinese))
[19]向欣,王义锋,孟国涛,等.大跨度地下洞室拱顶稳定性及支护措施研究[J].岩石力学与工程学报,2012,31(增2):3643-3649.(Xiang Xin,Wang Yifeng,Meng Guotao,et al.Study of stability and supporting measures of chamber arch crown for large span underground caverns[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Supp.2):3643-3649.(in Chinese)).