地震边坡失稳机理及稳定性分析
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摘要
通过对汶川地震边坡调研,发现大量边坡破坏形式为坡顶拉裂、下部坡体剪切破坏。本文利用有限差分程序,从边坡土体的应力状态出发,通过监测边坡土体的状态、位移和剪应变增量变化等,分析了岩土体在静力、横向地震和耦合地震作用下的破坏过程,发现坡顶附近发生张破坏,以下部位发生剪切破坏,而非传统的地质工程观点——地震边坡破坏主要是地震惯性力造成的剪切破坏。并提出一种新方法——关键点相对位移法,来判断边坡的动力稳定性,数值模拟结果与已有研究成果及震后灾害调查结果具有良好的一致性。
Investigation of the slopes in Wenchuan earthquake shows that tension failures mostly appear in the slope crests,and shear failure in slope toe.Beginning with the stress state of soil,using the finite-difference method,the failure process of slope is analyzed under the given conditions of static,horizontal and coupled earthquake by monitoring the changing of state,displacement,and shear-strain increment.The calculated results indicate that the slope crest is tensile damage and shear failure appears in slope toe.It is different from the traditional opinion of geological engineering that slope damage under earthquakes is mainly shear failure due to seismic inertia force.A new method of the relative displacement of key points is put out to judge the dynamic stability.Numerical simulation results have good consistency with existing research results and postseismic investigation findings.
Investigation of the slopes in Wenchuan earthquake shows that tension failures mostly appear in the slope crests,and shear failure in slope toe.Beginning with the stress state of soil,using the finite-difference method,the failure process of slope is analyzed under the given conditions of static,horizontal and coupled earthquake by monitoring the changing of state,displacement,and shear-strain increment.The calculated results indicate that the slope crest is tensile damage and shear failure appears in slope toe.It is different from the traditional opinion of geological engineering that slope damage under earthquakes is mainly shear failure due to seismic inertia force.A new method of the relative displacement of key points is put out to judge the dynamic stability.Numerical simulation results have good consistency with existing research results and postseismic investigation findings.
引文
[1]黄润秋,李为乐.“5.12”汶川大地震触发地质灾害的发育分布规律研究[J].岩石力学与工程学报,2009,27(12):2585~2592.Huang Runqiu,Li Weile.Research on development and distribu-tion on rules of geohazards induced by wenchuan earthquake on12thMay.Chinese Journal of Rock Mechanics and Engineering,2009,27(12):2585~2592.
[2]祁生文,伍法权,严福章,刘春玲.岩质边坡动力反应分析[M].北京:科学出版社,2007.Qi Shengwen,Wu Faquan,Yan Fuzhang.Dynamic Response ofRock Slope Analysis.Beijing:Science Press,2007.
[3]Boore D M,Harmsen S C,Harding S T.Wave scattering from astep change in surface topography.Bull.Seismol.Soc.Am,1981,71(1):117~25.
[4]George D.Bouckovalas,Achilleas G.Papadimitriou.Numerical e-valuation of slope topography effects on seismic ground motion[J].Soil Dynamics and Earthquake Engineering 2005,(25):547~558.
[5]Ashford S,Sitar N.Analysis of topographic amplification of in-clined shear waves in a steep coastal bluff.Bull Seismol Soc Am1997;87(3):692~700.
[6]Ashford S,Sitar N,Lysmer J,Deng N.Topographic effects on theseismic response of steep slopes.Bull Seismol Soc Am 1997;87(3):701~709.
[7]姜彤,马莎,许兵,马瑾.边坡在地震作用下的加卸载响应规律研究[J].岩石力学与工程学报,2004,22(23):3803~3807.Jang Tong,Ma Sha,Xu Bing,Ma Jin.Study on laws of load-unloadresponse of slope under seismic load.Chinese Journal of Rock Me-chanics and Engineering,2004,22(23):3803~3807.
[8]李海波,肖克强,刘亚群.地震荷载作用下顺层岩质边坡安全系数分析[J].岩石力学与工程学报,2007,26(12):2385~2394.Li Haibo,Xiao Keqiang,Liu Yaqun.Factor of safety analysis ofbedding rock slope under seismic load.Chinese Journal of RockMechanics and Engineering.2007,26(12):2385~2394.
[9]郑颖人,叶海林,黄润秋.地震边坡破坏机制及其破裂面的分析探讨[J].岩石力学与工程学报,2009,28(8):1714~1723.Zheng Yingren,Ye Hailin,Huang Runqiu.Analysis and discussionof failure mechanism and fracture surface of slope under earth-quake.Chinese Journal of Rock Mechanics and Engineering,2009,28(8):1714~1723.
[10]黄润秋.汶川8.0级地震触发崩滑灾害机制及其地质力学模式[J].岩石力学与工程学报,2009,28(6):1239~1249.Huang Runqiu.Mechanism and geotechnical modes of landslidehazards triggered by Wenchuan 8.0 earthquake.Chinese Journalof Rock Mechanics and Engineering,2009,28(6):1239~1249.
[11]卢萌盟,卫明山,等.全长黏结式预应力锚索加固基坑仿真实验研究[J].岩土工程学报,2006,28(1):92~96.Lu Mengmeng,Wei Mingshan,et al.Simulation tests on pit foun-dation reinforced by full-length-bonding pre-stressed cables.Chi-nese Journal of Geotechnical Engineering,2006,28(1):92~96.
[12]张倬元,王士天,王兰生.工程地质分析原理[M].北京:地质出版社,1993.Zhang Zhuoyuan,Wang Shitian,Wang Lansheng.Principles ofEngineering Geology.Beijing:Geological Publishing House,1993.
[13]胡广韬.滑坡动力学[M].北京:地质出版社,1995.Hu Guangtao.Landslide Dynamics.Beijing:Geological Publish-ing House,1995.
[14]许强,黄润秋.5.12汶川大地震诱发大型崩滑灾害动力特征初探[J].工程地质学报.2008,721~729.Xu Qiang,Huang Runqiu.Kinetics characteristics of large land-slides triggered by may 12th Wenchuan earthquake.Journal ofEngineering Geology.2008,721~729.
[15]李秀珍,孔纪名,邓红艳,等.“5.12”汶川地震滑坡特征及失稳破坏模式分析[J].四川大学学报(工程科学版).2009,(41)3:72~77.Li Xiuzhen,Kong Jiming,Deng Hongyan,et al.Analysis oncharacteristics and deformation failure mode of large-scale land-slides induced by“5.12”Wenchuan earthquake.Journal of Si-chuan University(Engineering Science edition).2009,(41)3:72~77.
[16]Lin ML,Wang KL.Seismic slope behavior in a large-scale sha-king table model test[J].Engineering Geology,2006,86(2):118~133.
[2]祁生文,伍法权,严福章,刘春玲.岩质边坡动力反应分析[M].北京:科学出版社,2007.Qi Shengwen,Wu Faquan,Yan Fuzhang.Dynamic Response ofRock Slope Analysis.Beijing:Science Press,2007.
[3]Boore D M,Harmsen S C,Harding S T.Wave scattering from astep change in surface topography.Bull.Seismol.Soc.Am,1981,71(1):117~25.
[4]George D.Bouckovalas,Achilleas G.Papadimitriou.Numerical e-valuation of slope topography effects on seismic ground motion[J].Soil Dynamics and Earthquake Engineering 2005,(25):547~558.
[5]Ashford S,Sitar N.Analysis of topographic amplification of in-clined shear waves in a steep coastal bluff.Bull Seismol Soc Am1997;87(3):692~700.
[6]Ashford S,Sitar N,Lysmer J,Deng N.Topographic effects on theseismic response of steep slopes.Bull Seismol Soc Am 1997;87(3):701~709.
[7]姜彤,马莎,许兵,马瑾.边坡在地震作用下的加卸载响应规律研究[J].岩石力学与工程学报,2004,22(23):3803~3807.Jang Tong,Ma Sha,Xu Bing,Ma Jin.Study on laws of load-unloadresponse of slope under seismic load.Chinese Journal of Rock Me-chanics and Engineering,2004,22(23):3803~3807.
[8]李海波,肖克强,刘亚群.地震荷载作用下顺层岩质边坡安全系数分析[J].岩石力学与工程学报,2007,26(12):2385~2394.Li Haibo,Xiao Keqiang,Liu Yaqun.Factor of safety analysis ofbedding rock slope under seismic load.Chinese Journal of RockMechanics and Engineering.2007,26(12):2385~2394.
[9]郑颖人,叶海林,黄润秋.地震边坡破坏机制及其破裂面的分析探讨[J].岩石力学与工程学报,2009,28(8):1714~1723.Zheng Yingren,Ye Hailin,Huang Runqiu.Analysis and discussionof failure mechanism and fracture surface of slope under earth-quake.Chinese Journal of Rock Mechanics and Engineering,2009,28(8):1714~1723.
[10]黄润秋.汶川8.0级地震触发崩滑灾害机制及其地质力学模式[J].岩石力学与工程学报,2009,28(6):1239~1249.Huang Runqiu.Mechanism and geotechnical modes of landslidehazards triggered by Wenchuan 8.0 earthquake.Chinese Journalof Rock Mechanics and Engineering,2009,28(6):1239~1249.
[11]卢萌盟,卫明山,等.全长黏结式预应力锚索加固基坑仿真实验研究[J].岩土工程学报,2006,28(1):92~96.Lu Mengmeng,Wei Mingshan,et al.Simulation tests on pit foun-dation reinforced by full-length-bonding pre-stressed cables.Chi-nese Journal of Geotechnical Engineering,2006,28(1):92~96.
[12]张倬元,王士天,王兰生.工程地质分析原理[M].北京:地质出版社,1993.Zhang Zhuoyuan,Wang Shitian,Wang Lansheng.Principles ofEngineering Geology.Beijing:Geological Publishing House,1993.
[13]胡广韬.滑坡动力学[M].北京:地质出版社,1995.Hu Guangtao.Landslide Dynamics.Beijing:Geological Publish-ing House,1995.
[14]许强,黄润秋.5.12汶川大地震诱发大型崩滑灾害动力特征初探[J].工程地质学报.2008,721~729.Xu Qiang,Huang Runqiu.Kinetics characteristics of large land-slides triggered by may 12th Wenchuan earthquake.Journal ofEngineering Geology.2008,721~729.
[15]李秀珍,孔纪名,邓红艳,等.“5.12”汶川地震滑坡特征及失稳破坏模式分析[J].四川大学学报(工程科学版).2009,(41)3:72~77.Li Xiuzhen,Kong Jiming,Deng Hongyan,et al.Analysis oncharacteristics and deformation failure mode of large-scale land-slides induced by“5.12”Wenchuan earthquake.Journal of Si-chuan University(Engineering Science edition).2009,(41)3:72~77.
[16]Lin ML,Wang KL.Seismic slope behavior in a large-scale sha-king table model test[J].Engineering Geology,2006,86(2):118~133.
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