高地应力条件下大型地下厂房松动区变化规律及参数反演
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摘要
松动区是控制地下洞室围岩变形及失稳的重要因素。以锦屏一级水电站为例,结合声波测试及多点位移计监测成果,对高地应力和低强度应力比条件下大型地下厂房围岩松动区的分布及变化特征进行分析,并采用BP网络和遗传算法对围岩参数进行反演。研究表明,声波测试的围岩松弛深度与多点位移计监测得到的围岩主要变形深度具有一致性,围岩松弛深度变化趋势与岩壁位移变化也存在对应关系,两者结合可以对围岩松动区的变化规律进行连续的分析。高地应力和低强度应力比条件下的松动区深度远大于一般应力条件,由于围岩应力状态调整、岩体破坏所导致的卸荷松弛成为围岩松弛的主要因素。开挖过程中,由于围岩应力状态的逐步调整,导致围岩的破坏和松弛的渐进发展,其中松弛深度在水平向的扩展较为明显。反演得到的松动区岩体变形模量及黏聚力较未松动岩体有明显降低,而摩擦角降低较少。因此,对松动区岩体进行灌浆加固,将有助于提高松动区岩体的变形模量和粘聚力,从而增强围岩的稳定性。
Excavation damaged zone (EDZ) is an important factor to the deformation and stability of underground caverns. Taking JinpingⅠHydropower Project for example, the distribution and variation of EDZ for large scale underground powerhouse under the conditions of high geostress and low strength-to-stress ratio are analyzed according to sonic wave measuring and multipoint extensometers monitoring; and the parameters of rockmass are back analyzed by BP network and genetic algorithm. The analytical results indicate that the depth of EDZ obtained by sonic wave measuring is consistent with the main deforming depth obtained by multipoint extensometers; and the depth change of EDZ is corresponding with the surface displacement change of rockmass; therefore the variation of EDZ can be analyzed continuously by the integrated using of sonic wave measuring and multipoint extensometers monitoring. Under the condition of high geostress and low strength-to-stress ratio, the depth of EDZ is much larger than general stress condition; and the unloading relaxation becomes the main factor of surrounding relaxation. The depth of EDZ increases with the stress adjustment of surrounding rock during excavating, in which the horizontal extending of EDZ is obvious. The deformation modulus E and cohesion c of EDZ carried by back analysis is markedly lower than undamaged rockmass, while the reducing of friction angle φ is less. Therefore, the grouting reinforcement of damaged rockmass will be benefit to improve its deformation modulus and cohesion; and the stability of surrounding rockmass will be improved consequently.
Excavation damaged zone (EDZ) is an important factor to the deformation and stability of underground caverns. Taking JinpingⅠHydropower Project for example, the distribution and variation of EDZ for large scale underground powerhouse under the conditions of high geostress and low strength-to-stress ratio are analyzed according to sonic wave measuring and multipoint extensometers monitoring; and the parameters of rockmass are back analyzed by BP network and genetic algorithm. The analytical results indicate that the depth of EDZ obtained by sonic wave measuring is consistent with the main deforming depth obtained by multipoint extensometers; and the depth change of EDZ is corresponding with the surface displacement change of rockmass; therefore the variation of EDZ can be analyzed continuously by the integrated using of sonic wave measuring and multipoint extensometers monitoring. Under the condition of high geostress and low strength-to-stress ratio, the depth of EDZ is much larger than general stress condition; and the unloading relaxation becomes the main factor of surrounding relaxation. The depth of EDZ increases with the stress adjustment of surrounding rock during excavating, in which the horizontal extending of EDZ is obvious. The deformation modulus E and cohesion c of EDZ carried by back analysis is markedly lower than undamaged rockmass, while the reducing of friction angle φ is less. Therefore, the grouting reinforcement of damaged rockmass will be benefit to improve its deformation modulus and cohesion; and the stability of surrounding rockmass will be improved consequently.
引文
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[2]杨志法,王思敬,冯紫良,等.岩土工程反分析原理及应用[M].北京:地震出版社,2002.
[3]郭凌云,肖明.地下工程岩体参数场反演分析应用研究[J].岩石力学与工程学报,2008,27(增刊2):3822-3826.GUO Ling-yu,XIAO Ming.Back-analysis and application study on surrounding rock parameter field of underground engineering[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(Supp.2):3822-3826.
[4]邹红英,肖明.地下洞室开挖松动圈评估方法研究[J].岩石力学与工程学报,2010,29(3):513-519.ZHOU Hong-ying,XIAO Ming.Study of methodology for assessment of excavation disturbed zone of underground caverns[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(3):513-519.
[5]李维树.隔河岩电站洞群围岩松动圈检测及其厚度分析[J].长江科学院院报,1995,12(2):44-48.LI Wei-shu.Detection and analysis on thickness of loosened collar in surrounding rock of galleries in Geheyan Project[J].Journal of Yangtze River Scientific Research Institute,1995,12(2):44-48.
[6]柳厚祥,方风华.预埋式多点位移计现场确定围岩松动圈的方法研究[J].冶矿工程,2006,26(1):1-4.LIU Hou-xiang,FANG Feng-hua.Study on the method to define the wall rocks loose2one with embedded displacement meter[J].Mining and Metallurgical Engineering,2006,26(1):1-4.
[7]邓建辉,王浩,姜清辉,等.利用滑动变形计监测岩石边坡松动区[J].岩石力学与工程学报,2002,21(2):180-184.DENG Jian-hui,WANG Hao,JIANG Qing-hui,et al.Monitor of disturbed zone for rock slope by sliding deformeter[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(2):180-184.
[8]靖洪文,李元海,梁军起,等.钻孔摄像测试围岩松动圈的机理与实践[J].中国矿业大学学报,2009,38(5):645-649.JIN Hong-wen,LI Yuan-hai,LIANG Jun-qi,et al.Borehole camera technology for measuring the relaxation zone of surrounding rock:mechanism and application[J].Journal of China University of Mining&Technology,2009,38(5):645-649.
[9]中国水电顾问集团成都勘测设计研究院.四川省雅砻江锦屏一级水电站地下厂房洞室群施工期围岩稳定与支护复核设计报告[R].成都:中国水电顾问集团成都勘测设计研究院,2009.
[10]中国水电顾问集团成都勘测设计研究院.锦屏一级水电站地下厂房洞室群围岩质量物探检测阶段成果报告[R].成都:中国水电顾问集团成都勘测设计研究院,2009.
[11]周华,汪卫明,陈胜宏.岩体开挖松弛的判据与有限元分析[J].华中科技大学学报(自然科学版),2009,37(6):112-116.ZHOU Hua,WANG Wei-ming,CHEN Sheng-hong.Relaxation criterion and finite element analysis of rock mass excavation[J].J.Huazhong Univ.of Sci.&Tech.(Natural Science Edition),2009,37(6):112-116.
[12]李仲奎,周钟,汤雪峰,等.锦屏一级水电站地下厂房洞室群稳定性分析与思考[J].岩石力学与工程学报,2009,28(11):2167-2175.LI Zhong-kui,ZHOU Zhong,TANG Xue-feng,et al.Stability analysis and considerations of underground powerhouse caverns group of JinpingⅠHydropower Station[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(11):2167-2175.
[13]魏进兵,邓建辉,王俤剀,等.锦屏一级水电站地下厂房围岩变形与破坏特征分析[J].岩石力学与工程学报,2010,29(6)WEI Jin-bing,DENG Jian-hui,WANG Di-kai,et al.Characterization of deformation and fracture for the rockmass in the underground powerhouse of JinpingⅠHydropower Station[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(6)
[14]JOEY ROGERS.Object-Oriented Neural Networks in C++[M].London:Academic Press,Inc,1997.
[15]邓建辉,李焯芬,葛修润.BP网络和遗传算法在岩石边坡位移反分析中的应用[J].岩石力学与工程学报,2001,20(1):1-5.DENG Jian-hui,LEE C F,GE Xiu-run.Application of BP network and genetic algorithm to displacement back analysis of rock slopes[J].Chinese Journal of Rock Mechanics and Engineering,2001,20(1):1-5.
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