云南鲁甸M_S6.5地震红石岩滑坡稳定性的数值模拟
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摘要
2014年8月3日鲁甸MS6.5地震触发了大量的滑坡崩塌,其中,位于鲁甸县李家山村和巧家县红石岩村交界处的牛栏江干流北岸的红石岩滑坡规模巨大,与此处位于左岸的红石岩古滑坡体的前缘部分一起堵塞了牛栏江而形成高达120m、体积达1 200×104m3的大型堰塞体。通过震后开展的野外实地调查,获得了红石岩滑坡发生处的地形地貌、地质构造、岩体结构及物质组成等资料。以这些第一手资料为基础,构建了红石岩滑坡的边坡模型,并应用边坡稳定性分析软件Geo Studio中Slope/W模块分别计算了红石岩滑坡体震前坡体安全系数和地震作用下的坡体安全系数。结果表明,红石岩滑坡体发生处的坡体安全系数在地震前为1.450,处于相对稳定状态,而鲁甸地震的地震动作用则使坡体的安全系数降低至0.962,直接导致红石岩坡体的失稳。文中进一步讨论了坡体滑动面的存在与否对坡体稳定性的影响:安全系数计算的结果表明,在中强地震作用下,先存滑动面的存在是导致大型滑坡形成的重要条件;对于高陡岩质边坡,如果没有先存滑动面,只可能形成浅表性滑坡。
Although the landslides triggered during earthquake events are common phenomena in the southwest China, the occurrence of the Hongshiyan landslide triggered by the MS6. 5 Ludian earthquake in 2014 is attractive for its giant volume which exceeds ten million cubic meters. The Hongshiyan landslide formed a quake lake and inundated a village. Based on the geological and geomophological data obtained through the immediate field investigation after the earthquake,we build the Hongshiyan slope model and at the same time,we apply numerical simulation to study the landslide formation. Result indicates that the Hongshiyan slope was at safe conditions with the Factor of safety( Fs) value greater than 1,but the ground seismic motion during the Ludian earthquake lowered its Fs to a value smaller than 1,which resulted in the occurrence of the landslide. Moreover,this study shows that an existing slip surface is important for generating a giant landslide,and steep slopes without existing slip surfaces are likely to generate shallow landslides with normal volumes.
Although the landslides triggered during earthquake events are common phenomena in the southwest China, the occurrence of the Hongshiyan landslide triggered by the MS6. 5 Ludian earthquake in 2014 is attractive for its giant volume which exceeds ten million cubic meters. The Hongshiyan landslide formed a quake lake and inundated a village. Based on the geological and geomophological data obtained through the immediate field investigation after the earthquake,we build the Hongshiyan slope model and at the same time,we apply numerical simulation to study the landslide formation. Result indicates that the Hongshiyan slope was at safe conditions with the Factor of safety( Fs) value greater than 1,but the ground seismic motion during the Ludian earthquake lowered its Fs to a value smaller than 1,which resulted in the occurrence of the landslide. Moreover,this study shows that an existing slip surface is important for generating a giant landslide,and steep slopes without existing slip surfaces are likely to generate shallow landslides with normal volumes.
引文
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Chen X L,Zhou Q,Ran H L,et al.2012.Earthquake-triggered landslides in southwest China[J].Nat HazardsEarth Syst Sci,12:351—363.
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Fellenius W.1936.Calculation of the stability of earth dams[A].In:Transactions of the 2nd Congress on LargeDams,Washington D C,4:445—462.
Fredlund D G,Krahn J.1977.Comparison of slope stability methods of analysis[J].Canadian Geotechnical Journal,14(3):429—439.
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Hermanns R L,Strecker M R.1999.Structural and lithological controls on large Quaternary rock avalanches(sturzstroms)in arid northwestern Argentina[J].Geologicla Society of America Bulletin,111(6):934—948.
Highland L M,Bobrowsky P.2008.The landslide handbook:A guide to understanding landslides[J].Reston,Virginia,U S Geological Survey Circular,1325:129p.
Huang Run-qiu.2015.Understanding the mechanism of large-scale landslides[A].In:G Lollino et al.(eds).Engineering Geology for Society and Territory-Volume 2.Springer International Publishing Switzerland,2015.
Janbu N.1954.Applications of composite slip surfaces for stability analysis[A].In:Proceedings of the EuropeanConference on the Stability of Earth Slopes,Stockholm.3:39—43.
Keefer D K.1984.Landslides caused by earthquakes[J].Geological Society of America Bulletin,95:406—421.
Meunier P,Hovius N,Haines J A.2007.Regional patterns of earthquake-triggered landslides and their relation toground motion[J].Geophys Res Lett,34:L20408.doi:10.1029/2007GL031337,2007.
Morgenstern N R,Price V E.1965.The analysis of the stability of general slip surfaces[J].Geotechnique,15:79—93.
Qi S W,Xu Q,Zhang B,et al.2011.Source characteristics of long runout rock avalanches triggered by the 2008Wenchuan earthquake,China[J].Journal of Asian Earth Sciences,40:896—906.
Yuan R M,Xu X W,Chen G H,et al.2010.Ejection landslide at northern terminus of Beichuan rupture triggered bythe 2008 MW7.9 Wenchuan earthquake[J].Bulletin of the Seismological Society of America,100:2689—2699.doi:10.1785/0120090256.
黄润秋,李为乐.2008.“5.12”汶川大地震触发地质灾害的发育规律研究[J].岩石力学与工程学报,27(12):2585—2592.HUANG Run-qiu,LI Wei-le.2008.A study on the development and distribution rules of geohazards triggered b“5.12”Wenchuan earthquake[J].Chinese Journal of Rock Mechanics and Engineering,27(12):2585—2592(in Chinese).
黄润秋,裴向军,张伟锋,等.2009.再论大光包滑坡特征与形成机制[J].工程地质学报,17(6):725—736.HUANG Run-qiu,PEI Xiang-jun,ZHANG Wei-feng,et al.2009.Further examination on characteristics and formatiomechanism of Daguangbao landslide[J].Journal of Engineering Geology,17(6):725—736(in Chinese).
黄润秋,张伟峰,裴向军.2014.大光包滑坡工程地质研究[J].工程地质学报,22(4):557—585.HUANG Run-qiu,ZHANG Wei-feng,PEI Xiang-jun.2014.Engineering geological study on Daguangbao landslid[J].Journal of Engineering Geology,22(4):557—585(in Chinese).
李天池.1979.地震与滑坡的关系及地震滑坡预测的探讨(节录)[A].滑坡文集(二).北京:人民铁道出版社.LI Tian-chi.1979.Relationship between earthquake and landslides and prediction of earthquake induced landslide[A].Landslide Anthology(Ⅱ).The People's Railway Publishing House,Beijing(in Chinese).
祁生文,伍法权,刘春玲,等.2004.地震边坡稳定性的工程地质分析[J].岩石力学与工程学报,23(16):2792—2797.QI Sheng-wen,WU Fa-quan,LIU Chun-ling,et al.2004.Engineering geology analysis on stability of slope undeearthquake[J].Chinese Journal of Rock Mechanics and Engineering,23(16):2792—2797(in Chinese).
闻学泽,杜方,易桂喜,等.2013.川滇交界东段昭通-莲峰断裂带的地震危险背景[J].地球物理学报,56(10):3361—3372.WEN Xue-ze,DU Fang,YI Gui-xi,et al.2013.Earthquake potential of the Zhaotong-Lianfeng Fault zone of theastern Sichuan-Yunnan border region[J].Chinese Journal of Geophysics.56(10):3361—3372(in Chinese).
许强,李为乐.2010.汶川地震诱发大型滑坡分布规律研究[J].工程地质学报,18(6):818—826.XU Qiang,LI Wei-le.2010.Distribution of large scale landslides induced by the Wenchuan earthquake[J].Journaof Engineering Geology,18(6):818—826(in Chinese).
周庆,江亚风,吴果,等.2014.芦山地震崩滑灾害空间分析及相关问题探讨[J].地震地质,36(2):344—357.doi:10.3969/j.issn.0253-4967.2014.02.006.ZHOU Qing,JIANG Ya-feng,WU Guo,et al.2014.Distribution of coseismic landslides in Lushan earthquake anddiscussion on related problems[J].Seismology and Geology,36(2):344—357(in Chinese).
Bishop A W,Morgenstern N.1960.Stability coefficients for earth slopes[J].Geotechnique,10(4):164—169.
Chang Z F,Chen X L,An X W,et al.2015.Why the 2014 Ludian,Yunnan,China MS6.5 earthquake triggered anunusually large landslide?[J]Nat Hazards Earth Syst Sci Discuss,3:367—399.doi:10.5194/nhessd-3-367—2015.
Chen X L,Zhou Q,Ran H L,et al.2012.Earthquake-triggered landslides in southwest China[J].Nat HazardsEarth Syst Sci,12:351—363.
Chen X L,Ran H L,Yang W T.2012.Evaluation of factors controlling large earthquake-induced landslides by theWenchuan earthquake[J].Nat Hazards Earth Syst Sci,12:3645—3657.
Fellenius W.1936.Calculation of the stability of earth dams[A].In:Transactions of the 2nd Congress on LargeDams,Washington D C,4:445—462.
Fredlund D G,Krahn J.1977.Comparison of slope stability methods of analysis[J].Canadian Geotechnical Journal,14(3):429—439.
GEO-SLOPE International Ltd.2010.Stability Modeling with SLOPE/W 2007 Version[M].Printed in Canada.
Guzzetti F,Carrara A,Cardinali M,et al.1999.Landslide hazard evaluation:A review of current techniques andtheir application in a multi-scale study,Central Italy[J].Geomorphology,31:181—216.
Harp E L,Wilson R C,Wieczorek G F.1981.Landslides from the February 4,1976,Guatemala earthquake[R].US Geological Survey Professional Paper,1204A.
Hermanns R L,Strecker M R.1999.Structural and lithological controls on large Quaternary rock avalanches(sturzstroms)in arid northwestern Argentina[J].Geologicla Society of America Bulletin,111(6):934—948.
Highland L M,Bobrowsky P.2008.The landslide handbook:A guide to understanding landslides[J].Reston,Virginia,U S Geological Survey Circular,1325:129p.
Huang Run-qiu.2015.Understanding the mechanism of large-scale landslides[A].In:G Lollino et al.(eds).Engineering Geology for Society and Territory-Volume 2.Springer International Publishing Switzerland,2015.
Janbu N.1954.Applications of composite slip surfaces for stability analysis[A].In:Proceedings of the EuropeanConference on the Stability of Earth Slopes,Stockholm.3:39—43.
Keefer D K.1984.Landslides caused by earthquakes[J].Geological Society of America Bulletin,95:406—421.
Meunier P,Hovius N,Haines J A.2007.Regional patterns of earthquake-triggered landslides and their relation toground motion[J].Geophys Res Lett,34:L20408.doi:10.1029/2007GL031337,2007.
Morgenstern N R,Price V E.1965.The analysis of the stability of general slip surfaces[J].Geotechnique,15:79—93.
Qi S W,Xu Q,Zhang B,et al.2011.Source characteristics of long runout rock avalanches triggered by the 2008Wenchuan earthquake,China[J].Journal of Asian Earth Sciences,40:896—906.
Yuan R M,Xu X W,Chen G H,et al.2010.Ejection landslide at northern terminus of Beichuan rupture triggered bythe 2008 MW7.9 Wenchuan earthquake[J].Bulletin of the Seismological Society of America,100:2689—2699.doi:10.1785/0120090256.
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