某高拱坝坝基开挖卸荷松弛时空效应
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摘要
水利水电工程中坝基开挖造成的岩体卸荷松弛是影响工程质量和安全的重要问题,查明岩体卸荷松弛的时间规律和空间特征,为加固工程设计方案提供数据依据具有重要意义。在某高拱坝坝基开挖过程中利用声波测井技术对建基面岩体进行大面积长期观测,对声波数据进行统计分析,并结合现场卸荷松弛现象,总结出岩体开挖所引起的岩体在一定时间和空间上的卸荷效应及发育特征。结果表明:岩体的卸荷松弛主要发生在开挖后的前8个月,10～12个月后基本结束;卸荷松弛的速率先快后慢;原岩的岩体结构越完整,卸荷效应越低,反之则越高;松弛带厚度与坡比之间存在一个最优坡比值;岩体的卸荷松弛是由浅入深渐进发展的,浅层岩体卸荷松弛程度明显高于深部岩体,且持续时间更长;结构面和软弱夹层是卸荷松弛的重要部位,影响大型岩块的稳定。
The unloading and relaxation of rock mass caused by excavation of dam foundation in water conservancy and hydropower project is an essential problem affecting engineering quality and safety.Identifying the temporal and spatial characteristics of unloading and relaxation of rock mass, and providing data basis for reinforcement engineering design are of substantial significance.In this paper, the unloading effect and development of rock mass caused by excavation of a high arch dam foundation are summarized in temporal and spatial senses based on long-term observations via acoustic logging during excavation.Results unveil that(1) unloading and relaxation of rock mass mainly occurs in the first eight months after excavation and basically ends after 10-12 months.(2) Unloading and relaxation develops rapidly at first and then slows down.(3) The more complete the structure of the original rock mass, the lower the unloading effect, and vise versa.(4) An optimal slope ratio leads to a smallest thickness of relaxation zone.(5) Unloading relaxation of rock mass develops gradually from the shallow to the deep. The degree of unloading relaxation of shallow rock mass is evidently higher than that of deep rock mass, and so does the duration of unloading.(6) Structural plane and weak interlayer are important parts of unloading relaxation which affect the stability of large rock blocks.
The unloading and relaxation of rock mass caused by excavation of dam foundation in water conservancy and hydropower project is an essential problem affecting engineering quality and safety.Identifying the temporal and spatial characteristics of unloading and relaxation of rock mass, and providing data basis for reinforcement engineering design are of substantial significance.In this paper, the unloading effect and development of rock mass caused by excavation of a high arch dam foundation are summarized in temporal and spatial senses based on long-term observations via acoustic logging during excavation.Results unveil that(1) unloading and relaxation of rock mass mainly occurs in the first eight months after excavation and basically ends after 10-12 months.(2) Unloading and relaxation develops rapidly at first and then slows down.(3) The more complete the structure of the original rock mass, the lower the unloading effect, and vise versa.(4) An optimal slope ratio leads to a smallest thickness of relaxation zone.(5) Unloading relaxation of rock mass develops gradually from the shallow to the deep. The degree of unloading relaxation of shallow rock mass is evidently higher than that of deep rock mass, and so does the duration of unloading.(6) Structural plane and weak interlayer are important parts of unloading relaxation which affect the stability of large rock blocks.
引文
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[2] 廖伟,何刚,许海燕,等.高地应力条件下岩体松弛时间效应检测[J].工程地球物理学报,2011,8(5):609-615.
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[8] 孙云志,黄润秋.谷坡岩体卸荷带划分量化指标研究[J].岩石力学与工程学报,2012,31(增刊2):3942-3949.
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[10] 王宏图,李晓红,杨春和,等.准各向同性裂隙岩体中有效动弹性参数与弹性波速关系的研究[J].岩土力学,26(6):873-876.
[11] 李晶,郭伟杰,李佳.西南某水电站建基面岩体爆破松弛研究[J].水电能源科学,2011,29(1):69-72.
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[13] 易毅,汤子坚,张春安.大岗山水电站坝基岩体表层低波速带成因分析[J].人民长江,2014,45(22):37-39,53.
[14] 杜怡韩,聂德新,赵其华.坝基开挖爆破松弛带划分及影响因素研究[J].人民长江,2012,43(11):46-49,94.
[15] 段雪琴,任光明,夏敏,等西南某水电站层状建基岩体松弛特征研究[J].工程地质学报,2014,22(1):124-129.
[16] 陈正峰,张勇.坝基开挖产生的爆破松弛带厚度确定[J].地质灾害与环境保护,2007(3):47-50.
[17] 肖国强,覃毅宝,王法刚,等.声波法在三峡工程永久船闸边坡岩体卸荷松弛监测中的应用[J].岩土力学,2006,27(增刊2):1235-1238.
[18] 易毅,何刚,汤子坚,等.高拱坝坝基岩体松弛时间及空间效应研究[J].水利规划与设计,2014(2):89-93.
[19] 倪绍虎,何世海,陈益民,等.柱状节理玄武岩的破坏模式、破坏机制及工程对策[J].岩石力学与工程学报,2016,35(增刊1):3064-3075.
[20] 刘将忠.声波传播速度、衰减系数与岩体结构面的关系[C]//重庆岩石力学与工程学会测试与分析专业委员会2000年学术交流会论文集.重庆:中国岩石力学与工程学会,2000:30-33.
[21] 巨广宏.高拱坝建基岩体开挖松弛工程地质特性研究[D].成都:成都理工大学,2011.
[22] 冯学敏,陈胜宏,李文纲.岩石高边坡开挖卸荷松弛准则研究与工程应用[J].岩土力学,2009,30(增刊2):452-456.
[23] 赵勇,许模,覃礼貌,等.中等地应力地区建基岩体卸荷松弛特征研究[J].四川大学学报(工程科学版),2014,46(3):7-14.
[24] 冯学敏.高坝建基面开挖卸荷松弛分析及启示[J].水电站设计,2010,26(1):1-7.
[2] 廖伟,何刚,许海燕,等.高地应力条件下岩体松弛时间效应检测[J].工程地球物理学报,2011,8(5):609-615.
[3] 游敏,聂德新.河谷斜坡卸荷综合分带研究[J].人民黄河,2011,33(1):103-105.
[4] 魏云杰.中国西南水电工程区峨眉山玄武岩岩体结构特性及其工程应用研究[D].成都:成都理工大学,2007.
[5] 任光明,巨广宏,聂德新,等.斜坡岩体卸荷分带量化研究[J].成都理工大学学报(自然科学版),2003,30(4):335-338.
[6] 郑达,黄润秋.高边坡岩体卸荷带划分的量化研究[J].水文地质工程地质,2006(5):9-12.
[7] 郑达,黄润秋.西南水电工程坝址峨眉山玄武岩卸荷分带研究[J].成都理工大学学报(自然科学版),2009,36(2):195-200.
[8] 孙云志,黄润秋.谷坡岩体卸荷带划分量化指标研究[J].岩石力学与工程学报,2012,31(增刊2):3942-3949.
[9] 庞波,郑达.基于模糊综合评判的峨眉山玄武岩卸荷分带量化研究[J].水利水电技术,2016,47(5):157-161,170.
[10] 王宏图,李晓红,杨春和,等.准各向同性裂隙岩体中有效动弹性参数与弹性波速关系的研究[J].岩土力学,26(6):873-876.
[11] 李晶,郭伟杰,李佳.西南某水电站建基面岩体爆破松弛研究[J].水电能源科学,2011,29(1):69-72.
[12] 何彩华.浅谈岩土工程勘查中的声波测井技术[J].广东科技,2012,21(9):108-109.
[13] 易毅,汤子坚,张春安.大岗山水电站坝基岩体表层低波速带成因分析[J].人民长江,2014,45(22):37-39,53.
[14] 杜怡韩,聂德新,赵其华.坝基开挖爆破松弛带划分及影响因素研究[J].人民长江,2012,43(11):46-49,94.
[15] 段雪琴,任光明,夏敏,等西南某水电站层状建基岩体松弛特征研究[J].工程地质学报,2014,22(1):124-129.
[16] 陈正峰,张勇.坝基开挖产生的爆破松弛带厚度确定[J].地质灾害与环境保护,2007(3):47-50.
[17] 肖国强,覃毅宝,王法刚,等.声波法在三峡工程永久船闸边坡岩体卸荷松弛监测中的应用[J].岩土力学,2006,27(增刊2):1235-1238.
[18] 易毅,何刚,汤子坚,等.高拱坝坝基岩体松弛时间及空间效应研究[J].水利规划与设计,2014(2):89-93.
[19] 倪绍虎,何世海,陈益民,等.柱状节理玄武岩的破坏模式、破坏机制及工程对策[J].岩石力学与工程学报,2016,35(增刊1):3064-3075.
[20] 刘将忠.声波传播速度、衰减系数与岩体结构面的关系[C]//重庆岩石力学与工程学会测试与分析专业委员会2000年学术交流会论文集.重庆:中国岩石力学与工程学会,2000:30-33.
[21] 巨广宏.高拱坝建基岩体开挖松弛工程地质特性研究[D].成都:成都理工大学,2011.
[22] 冯学敏,陈胜宏,李文纲.岩石高边坡开挖卸荷松弛准则研究与工程应用[J].岩土力学,2009,30(增刊2):452-456.
[23] 赵勇,许模,覃礼貌,等.中等地应力地区建基岩体卸荷松弛特征研究[J].四川大学学报(工程科学版),2014,46(3):7-14.
[24] 冯学敏.高坝建基面开挖卸荷松弛分析及启示[J].水电站设计,2010,26(1):1-7.