卸荷条件下层状岩体层厚变化规律及机制研究
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摘要
以黄河上游某水电站层状岩体斜坡为对象,通过90个勘探平硐和地表大量变质砂岩和板岩层厚的现场测量和统计,揭示层厚的空间变化规律,分析岩层薄化的影响因素及影响范围,并基于地应力测量、岩体波速测试、三轴应力–弹性波耦合试验和数值计算,探讨卸荷作用下陡倾层状岩体斜坡的岩层薄化机制。结果表明:岩层薄化是岩性、构造、卸荷和风化等因素综合作用的结果,软硬相间岩层及其潜在弱面是岩层薄化的基础,构造作用使潜在弱面剪切,卸荷作用使潜在弱面显性张裂,风化使地表岩层进一步变薄,其中卸荷作用是主要和全局性的。河流下切使软硬相间陡立层状岩体斜坡内的地应力场非常复杂,坡顶和坡面岩层内潜在弱面直接拉张,斜坡内一定深度范围内岩层沿潜在弱面发生压致拉裂,斜坡内陡立层状岩体发生大范围岩层薄化。受之影响,层状岩体斜坡内层厚总体上随深度增加振荡式增加并在一定深度达到原生厚度而趋于稳定,层间错动带、褶皱带、卸荷裂隙带附近的层厚普遍较薄并也随埋深增大而增加,岩层厚度及影响范围随高程增加而增加,左岸反倾岩层的厚度和影响范围大于右岸顺倾岩层。层厚、埋深、纵波速度和应力状态之间具有较好的相关性,表明层状岩体的单层厚度始终受地应力场控制。研究成果为层状岩体力学性质与变形破坏研究以及工程设计提供基础。
A layered rock slope of a hydropower station in the upper reaches of the Yellow River was taken as an object. The spatial variation laws of the layer thickness of metamorphic sandstones and slate were revealed through field measurement in 90 adits and on the ground,and the influence factors and the influence scope of layer thinning were analyzed. Based on in-situ stress measurements,rock mass wave velocity tests,stress-elastic wave coupling triaxial tests and numerical simulations,the mechanism of layer thinning in steeply inclined stratified rock slopes under unloading conditions was researched. The results show that layer thinning is led by the combination of lithology,geotectonic movement,unloading and weathering. The soft-hard interbedded rock mass and the potential weak planes are the foundation of layer thinning. The rock mass dislocates along the potential weak planes due to the geotectonic movements,the weak planes cracks under the action of unloading,and the shallow layers become thin more and more because of the weathering. River incision makes the stress field in the rock slope very complicated,which leads to that the potential weak planes within the slope crest and the slope develop into tension cracks. Meanwhile,the compression fractures along the potential weak planes happens within a certain depth range of the slope,and then layer thinning occurs in a wide range of the steeply stratified rock slope. As a result,the layer thickness in the stratified rock mass generally increases oscillatingly with depth and will tend to be the thickness of the original strata. Moreover,the layer thickness near the bedding fault zone,in the fold belts and near the unloading crack belts,is generally thinner and rises with increasing the burial depth. The layer thickness and its influence range increase with increasing the elevation,and the values of them in the anti-dip stratum at the left flank are greater than those in the right flank. In addition,there is a good correlation among the layer thickness,the depth of burial,the P-wave velocity and the geo-stress,which indicates that the layer thickness is always controlled by in-situ stress state. This research can provide references for the study of mechanical properties and deformation failure and for the design of rock engineering in the stratified rock mass.
A layered rock slope of a hydropower station in the upper reaches of the Yellow River was taken as an object. The spatial variation laws of the layer thickness of metamorphic sandstones and slate were revealed through field measurement in 90 adits and on the ground,and the influence factors and the influence scope of layer thinning were analyzed. Based on in-situ stress measurements,rock mass wave velocity tests,stress-elastic wave coupling triaxial tests and numerical simulations,the mechanism of layer thinning in steeply inclined stratified rock slopes under unloading conditions was researched. The results show that layer thinning is led by the combination of lithology,geotectonic movement,unloading and weathering. The soft-hard interbedded rock mass and the potential weak planes are the foundation of layer thinning. The rock mass dislocates along the potential weak planes due to the geotectonic movements,the weak planes cracks under the action of unloading,and the shallow layers become thin more and more because of the weathering. River incision makes the stress field in the rock slope very complicated,which leads to that the potential weak planes within the slope crest and the slope develop into tension cracks. Meanwhile,the compression fractures along the potential weak planes happens within a certain depth range of the slope,and then layer thinning occurs in a wide range of the steeply stratified rock slope. As a result,the layer thickness in the stratified rock mass generally increases oscillatingly with depth and will tend to be the thickness of the original strata. Moreover,the layer thickness near the bedding fault zone,in the fold belts and near the unloading crack belts,is generally thinner and rises with increasing the burial depth. The layer thickness and its influence range increase with increasing the elevation,and the values of them in the anti-dip stratum at the left flank are greater than those in the right flank. In addition,there is a good correlation among the layer thickness,the depth of burial,the P-wave velocity and the geo-stress,which indicates that the layer thickness is always controlled by in-situ stress state. This research can provide references for the study of mechanical properties and deformation failure and for the design of rock engineering in the stratified rock mass.
引文
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[2]SEMENZA E,GHIROTTI M.History of the 1963 Vajont slide:the importance of geological factors[J].Bulletin of Engineering Geology and the Environment,2000,59(2):87-97.
[3]黄润秋.20世纪以来中国的大型滑坡及其发生机制[J].岩石力学与工程学报,2007,26(3):433-454.(HUANG Runqiu.Large-scale landslides and their sliding mechanisms in China since the 20th century[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(3):433-454.(in Chinese))
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[5]李高勇,刘高,谢裕江.黄河上游某倾倒体的时效变形研究[J].工程地质学报,2013,21(6):835-841.(LI Gaoyong,LIU Gao,XIE Yujiang.Time-dependent deformation of toppling rock slope on upper reach of the Yellow River[J].Journal of Engineering Geology,2013,21(6):835-841.(in Chinese))
[6]ZHANG Z L,LIU G,WU S R,et al.Rock slope deformation mechanism in the Cihaxia Hydropower Station,Northwest China[J].Bulletin of Engineering Geology and the Environment,2015,74(3):943-958.
[7]姜秉秉.顺层岩质斜坡多级溃屈机制研究[硕士学位论文][D].兰州:兰州大学,2016.(JIANG Bingbing.Study on multi-buckling failure of the bedded rock masses on the consequent slopes[M.S.Thesis][D].Lanzhou:Lanzhou University,2016.(in Chinese))
[8]XU D P,FENG X T,CHEN D F,et al.Constitutive representation and damage degree index for the layered rock mass excavation response in underground openings[J].Tunnelling and Underground Space Technology,2017,64(Suppl.C):133-145.
[9]CHAJES A.Principles of structural stability theory[M].New Jersey:Prentice-Hall Inc.,Englewood Cliffs,1974:24-26.
[10]HU X Q.Buckling deformation in the Highwood Pass,Alberta,Canada[J].Canadian Geotechnical Journal,2011,30(2):276-286.
[11]汪小刚,贾志欣,陈祖煜,等.岩质边坡倾倒破坏的稳定分析方法[J].水利学报,1996,(3):7-12.(WANG Xiaogang,JIA Zhixin,CHENZuyu,et al.The research of stability analysis of toppling failure of jointed rock slopes[J].Journal of Water Conservancy,1996,(3):7-12.(in Chinese))
[12]CAVERS D S.Simple method to analyze buckling of rock slopes[J].Rock Mechanics,1981,14:87-104.
[13]朱晗迓,马美玲,尚岳全.顺倾向层状岩质边坡溃屈破坏分析[J].浙江大学学报:工学版,2004,38(9):1 144-1 149.(ZHU Hanya,MA Meiling,SHANG Yuequan.Analysis of buckling failure of consequent rock slope[J].Journal of Zhejiang University:Engineering Science,2004,38(9):1 144-1 149.(in Chinese))
[14]WU G,ZHANG L.Studying unloading failure characteristics of a rock mass using the disturbed state concept[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(Supp.1):419-425.
[15]HE M C,MIAO J L,FENG J L.Rock burst process of limestone and its acoustic emission characteristics under true-triaxial unloading conditions[J].International Journal of Rock Mechanics and Mining Sciences,2010,47(2):286-298.
[16]王瑞红,李建林,蒋昱州,等.含预制节理岩体卸荷条件下力学特性试验研究[J].岩土力学,2012,33(11):3 257-3 262.(WANGRuihong,LI Jianlin,JIANG Yuzhou,et al.Experimental research on mechanical property of rock mass with prefabricated joints under unloading condition[J].Rock and Soil Mechanics,2012,33(11):3 257-3 262.(in Chinese))
[17]熊良宵,虞利军,杨昌斌,等.卸载条件下层状岩体力学特性研究[J].岩石力学与工程学报,2014,33(增2):3 545-3 554.(XIONGLiangxiao,YU Lijun,YANG Changbin,et al.Research on mechanical characteristics of interlayered rock mass under unloading condition[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.2):3 545-3 554.(in Chinese))
[18]哈秋舲.岩石边坡工程与卸荷非线性岩石(体)力学[J].岩石力学与工程学报,1997,16(4):386-391.(HA Qiuling.Rock slope engineering and unloading nonlinear rock masses mechanics[J].Chinese Journal of Rock Mechanics and Engineering,1997,16(4):386-391.(in Chinese))
[19]费文平,张国强,崔华丽.高边坡卸荷岩体稳定性分析[J].武汉大学学报:工学版,2010,43(5):599-603.(FEI Wenping,ZHANGGuoqiang,CUI Huali.Stability analysis of unloading rock mass of high slopes[J].Engineering Journal of Wuhan University,2010,43(5):599-603.(in Chinese))
[20]黄书岭,王继敏,丁秀丽,等.基于层状岩体卸荷演化的锦屏I级地下厂房洞室群稳定性与调控[J].岩石力学与工程学报,2011,30(11):2 203-2 216.(HUANG Shuling,WANG Jimin,DING Xiuli,et al.Stability and control for underground caverns of Jingping Ihydropower station based on unloading evolution of layered rock mass[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(11):2 203-2 216.(in Chinese))
[21]张勇,李天鹏,聂德新,等.金沙江某水电站上下坝址岩体卸荷差异研究[J].工程地质学报,2009,17(3):313-316.(ZHANGYong,LI Tianpeng,NIE Dexin,et al.Unloading of the rock mass at the up and down stream dams of hydropower station in Jinsha river.Journal of Engineering Geology,2009,17(3):313-316.(in Chinese))
[22]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.(YOU Min,NIE Dexin.Study on the integrated zoning of unloading in slope of river valley[J].People?s Yellow River,2011,33(1):103-105.(in Chinese))
[23]孙广忠,张文彬.一种常见的岩体结构-板裂结构及其力学模型[J].地质科学,1985,28(3):275-282.(SUN Guangzhong,ZHANGWenbin.A common rock structure-board crack structure and its mechanical model[J].Chinese Journal of Geology,1985,28(3):275-282.(in Chinese))
[24]周辉,卢景景,徐荣超,等.深埋硬岩隧洞围岩板裂化破坏研究的关键问题及研究进展[J].岩土力学,2015,36(10):2 737-2 749.(ZHOU Hui,LU Jingjing,XU Rongchao,et al.Critical problems of study of slabbing failure of surrounding rock in deep hard rock tunnel and research progress[J].Rock and Soil Mechanics,2015,36(10):2 737-2 749.(in Chinese))
[25]马启超,薛玺成,郭怀志.对岩体地应力场分布规律的初步探讨[J].水利水电技术,1985,16(7):30-36.(MA Qichao,XUE Xicheng,GUO huaizhi.Research on the distribution law of in-situ stress field in rock mass[J].Water Resources and Hydropower Engineering,1985,16(7):30-36.(in Chinese))
[26]邓继新,史謌,刘瑞珣,等.泥岩、页岩声速各向异性及其影响因素分析[J].地球物理学报,2004,47(5):862-868.(DENG Jixin,SHI Ge,LIU Ruixun,et al.Analysis of the velocity anisotropy and its affection factors in shale and mudstone[J].Chinese Journal of Geophysics,2004,47(5):862-868.(in Chinese))
[27]刘高,韩文峰,李雪峰,等.金川矿山围岩动态演化及其力学参数研究[J].岩石力学与工程学报,2003,22(增2):2 588-2 594.(LIU Gao,HAN Wenfeng,LI Xuefeng.Dynamic evolution and mechanical parameters of surrounding rocks in Jinchuan nickel mine[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(Supp.2):2 588-2 594.(in Chinese))
[28]尹尚先,王尚旭.弹性模量、波速与应力的关系及其应用[J].岩土力学,2003,24(增2):597-601.(YIN Shangxian,WANG Shangxu.Relation of stresses with elastic modulus and wave velocities and its application[J].Chinese Journal of Geotechnical Engineering,2003,24(Supp.2):597-601.(in Chinese))
[29]陈祥,孙进忠,谭朝爽,等.岩块波速-应力关系及其卸荷效应[J].岩土工程学报,2010,32(5):757-761.(CHEN Xiang,SUNJinzhong,TAN Chaoshuang,et al.Relation between P-wave velocity and stress of rock samples and their unloading effect[J].Chinese Journal of Geotechnical Engineering,2010,32(5):757-761.(in Chinese))
[2]SEMENZA E,GHIROTTI M.History of the 1963 Vajont slide:the importance of geological factors[J].Bulletin of Engineering Geology and the Environment,2000,59(2):87-97.
[3]黄润秋.20世纪以来中国的大型滑坡及其发生机制[J].岩石力学与工程学报,2007,26(3):433-454.(HUANG Runqiu.Large-scale landslides and their sliding mechanisms in China since the 20th century[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(3):433-454.(in Chinese))
[4]TANG H M,ZOU Z X,XIONG C R,et al.An evolution model of large consequent bedding rockslides,with particular reference to the Jiweishan rockslide in Southwest China[J].Engineering Geology,2015,186(Suppl.C):17-27.
[5]李高勇,刘高,谢裕江.黄河上游某倾倒体的时效变形研究[J].工程地质学报,2013,21(6):835-841.(LI Gaoyong,LIU Gao,XIE Yujiang.Time-dependent deformation of toppling rock slope on upper reach of the Yellow River[J].Journal of Engineering Geology,2013,21(6):835-841.(in Chinese))
[6]ZHANG Z L,LIU G,WU S R,et al.Rock slope deformation mechanism in the Cihaxia Hydropower Station,Northwest China[J].Bulletin of Engineering Geology and the Environment,2015,74(3):943-958.
[7]姜秉秉.顺层岩质斜坡多级溃屈机制研究[硕士学位论文][D].兰州:兰州大学,2016.(JIANG Bingbing.Study on multi-buckling failure of the bedded rock masses on the consequent slopes[M.S.Thesis][D].Lanzhou:Lanzhou University,2016.(in Chinese))
[8]XU D P,FENG X T,CHEN D F,et al.Constitutive representation and damage degree index for the layered rock mass excavation response in underground openings[J].Tunnelling and Underground Space Technology,2017,64(Suppl.C):133-145.
[9]CHAJES A.Principles of structural stability theory[M].New Jersey:Prentice-Hall Inc.,Englewood Cliffs,1974:24-26.
[10]HU X Q.Buckling deformation in the Highwood Pass,Alberta,Canada[J].Canadian Geotechnical Journal,2011,30(2):276-286.
[11]汪小刚,贾志欣,陈祖煜,等.岩质边坡倾倒破坏的稳定分析方法[J].水利学报,1996,(3):7-12.(WANG Xiaogang,JIA Zhixin,CHENZuyu,et al.The research of stability analysis of toppling failure of jointed rock slopes[J].Journal of Water Conservancy,1996,(3):7-12.(in Chinese))
[12]CAVERS D S.Simple method to analyze buckling of rock slopes[J].Rock Mechanics,1981,14:87-104.
[13]朱晗迓,马美玲,尚岳全.顺倾向层状岩质边坡溃屈破坏分析[J].浙江大学学报:工学版,2004,38(9):1 144-1 149.(ZHU Hanya,MA Meiling,SHANG Yuequan.Analysis of buckling failure of consequent rock slope[J].Journal of Zhejiang University:Engineering Science,2004,38(9):1 144-1 149.(in Chinese))
[14]WU G,ZHANG L.Studying unloading failure characteristics of a rock mass using the disturbed state concept[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(Supp.1):419-425.
[15]HE M C,MIAO J L,FENG J L.Rock burst process of limestone and its acoustic emission characteristics under true-triaxial unloading conditions[J].International Journal of Rock Mechanics and Mining Sciences,2010,47(2):286-298.
[16]王瑞红,李建林,蒋昱州,等.含预制节理岩体卸荷条件下力学特性试验研究[J].岩土力学,2012,33(11):3 257-3 262.(WANGRuihong,LI Jianlin,JIANG Yuzhou,et al.Experimental research on mechanical property of rock mass with prefabricated joints under unloading condition[J].Rock and Soil Mechanics,2012,33(11):3 257-3 262.(in Chinese))
[17]熊良宵,虞利军,杨昌斌,等.卸载条件下层状岩体力学特性研究[J].岩石力学与工程学报,2014,33(增2):3 545-3 554.(XIONGLiangxiao,YU Lijun,YANG Changbin,et al.Research on mechanical characteristics of interlayered rock mass under unloading condition[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.2):3 545-3 554.(in Chinese))
[18]哈秋舲.岩石边坡工程与卸荷非线性岩石(体)力学[J].岩石力学与工程学报,1997,16(4):386-391.(HA Qiuling.Rock slope engineering and unloading nonlinear rock masses mechanics[J].Chinese Journal of Rock Mechanics and Engineering,1997,16(4):386-391.(in Chinese))
[19]费文平,张国强,崔华丽.高边坡卸荷岩体稳定性分析[J].武汉大学学报:工学版,2010,43(5):599-603.(FEI Wenping,ZHANGGuoqiang,CUI Huali.Stability analysis of unloading rock mass of high slopes[J].Engineering Journal of Wuhan University,2010,43(5):599-603.(in Chinese))
[20]黄书岭,王继敏,丁秀丽,等.基于层状岩体卸荷演化的锦屏I级地下厂房洞室群稳定性与调控[J].岩石力学与工程学报,2011,30(11):2 203-2 216.(HUANG Shuling,WANG Jimin,DING Xiuli,et al.Stability and control for underground caverns of Jingping Ihydropower station based on unloading evolution of layered rock mass[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(11):2 203-2 216.(in Chinese))
[21]张勇,李天鹏,聂德新,等.金沙江某水电站上下坝址岩体卸荷差异研究[J].工程地质学报,2009,17(3):313-316.(ZHANGYong,LI Tianpeng,NIE Dexin,et al.Unloading of the rock mass at the up and down stream dams of hydropower station in Jinsha river.Journal of Engineering Geology,2009,17(3):313-316.(in Chinese))
[22]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.(YOU Min,NIE Dexin.Study on the integrated zoning of unloading in slope of river valley[J].People?s Yellow River,2011,33(1):103-105.(in Chinese))
[23]孙广忠,张文彬.一种常见的岩体结构-板裂结构及其力学模型[J].地质科学,1985,28(3):275-282.(SUN Guangzhong,ZHANGWenbin.A common rock structure-board crack structure and its mechanical model[J].Chinese Journal of Geology,1985,28(3):275-282.(in Chinese))
[24]周辉,卢景景,徐荣超,等.深埋硬岩隧洞围岩板裂化破坏研究的关键问题及研究进展[J].岩土力学,2015,36(10):2 737-2 749.(ZHOU Hui,LU Jingjing,XU Rongchao,et al.Critical problems of study of slabbing failure of surrounding rock in deep hard rock tunnel and research progress[J].Rock and Soil Mechanics,2015,36(10):2 737-2 749.(in Chinese))
[25]马启超,薛玺成,郭怀志.对岩体地应力场分布规律的初步探讨[J].水利水电技术,1985,16(7):30-36.(MA Qichao,XUE Xicheng,GUO huaizhi.Research on the distribution law of in-situ stress field in rock mass[J].Water Resources and Hydropower Engineering,1985,16(7):30-36.(in Chinese))
[26]邓继新,史謌,刘瑞珣,等.泥岩、页岩声速各向异性及其影响因素分析[J].地球物理学报,2004,47(5):862-868.(DENG Jixin,SHI Ge,LIU Ruixun,et al.Analysis of the velocity anisotropy and its affection factors in shale and mudstone[J].Chinese Journal of Geophysics,2004,47(5):862-868.(in Chinese))
[27]刘高,韩文峰,李雪峰,等.金川矿山围岩动态演化及其力学参数研究[J].岩石力学与工程学报,2003,22(增2):2 588-2 594.(LIU Gao,HAN Wenfeng,LI Xuefeng.Dynamic evolution and mechanical parameters of surrounding rocks in Jinchuan nickel mine[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(Supp.2):2 588-2 594.(in Chinese))
[28]尹尚先,王尚旭.弹性模量、波速与应力的关系及其应用[J].岩土力学,2003,24(增2):597-601.(YIN Shangxian,WANG Shangxu.Relation of stresses with elastic modulus and wave velocities and its application[J].Chinese Journal of Geotechnical Engineering,2003,24(Supp.2):597-601.(in Chinese))
[29]陈祥,孙进忠,谭朝爽,等.岩块波速-应力关系及其卸荷效应[J].岩土工程学报,2010,32(5):757-761.(CHEN Xiang,SUNJinzhong,TAN Chaoshuang,et al.Relation between P-wave velocity and stress of rock samples and their unloading effect[J].Chinese Journal of Geotechnical Engineering,2010,32(5):757-761.(in Chinese))