汶川八级地震滑坡高速远程特征分析
|
摘要
汶川地震触发的高速远程滑坡主要沿龙门山主中央断裂带汶川映秀—安县高川—北川县城—平武南坝—青川一线地震破裂带展布。由于获得了1.5g以上的抛掷加速度,具有明显的气垫效应,估计最大滑动速度一般大于70m.s-1,滑动距离一般为滑体启动时长度的数倍甚至10多倍,堆积成坝形成多处堰塞湖,最大滑行距离达3.2km。本文重点解剖了位于地震破裂带南西段(初始震中)的汶川映秀牛圈沟滑坡—碎屑流、位于地震破裂带中段的北川城西滑坡和位于地震破裂带北东段青川东河口滑坡—碎屑流3个典型实例,认为具有如下特征:(1)岩性条件:母岩遭受长期构造动力作用,呈碎裂岩体,后期被强烈风化,岩体极为破碎;(2)抛掷效应:位于汶川地震主断裂带或附近,垂直加速度大于水平加速度,强地面运动持时长,岩体发生振胀和抛掷;(3)碰撞效应:上部滑坡体发生高位剪出和高位撞击,致使岩体碎屑化;(4)铲刮效应:撞击作用导致下部山体被铲刮,形成次级滑坡,为碎屑流体提供了足够展翼和抛洒物源体积;(5)气垫效应:碎屑化岩体快速抛掷导致下部沟谷空气迅速谷状圈闭和向下紊流,形成气垫效应,或者,在下部地形开阔地带压缩空气呈层流状态致使滑体凌空飞行。
The extremely rapid and long run-out landslides triggered by the Wenchuan Earthquake were occurred along the Yingxiu-Gaochuan-Beichuan-Nanba-Qingchuan of the main seismic fault.The estimated maximum sliding velocity is greater than 70m·s-1 under the over 1.5g earthquake acceleration,compared with conventional rainfall or liquefaction induced landslides.The run-out distance of landslide-debris is several or several ten times of the rockmass length from crown to exit due to the air layer lubrication in where lots of landslide dams occurred.The maximum run-out distance is 3200m.The three cases are studied from the Niuquangou rockslide-debris flow at the south west segment of the main seismic fault(Yingxiu,Wenchuan),the Chengxi rockslide at the middle segment of the main seismic fault(Beichuan) and the Donghekou rockslide-debris flow at the north east segment of the main seismic fault.The three cases illustrates following common characteristics:(1)parent rockmass is broken under long geologic processing and weathered;(2) Rockmass was separately expanded and thrown under long-period strong ground vibration in which the vertical motion was predominant along the main seismic fault;(3)sliding mass was crashed at the exiting zone and transferred to fragment material;(4) The secondary landslide was triggered underneath the exiting zone due to the powerful crashing and shaving processes that provides more mass to debris body and cushion shape;(5) The a long run-out distance fragment flow is occurred under air layer lubrication.The air layer was pressed and turbulently flowed in the narrow-shaped valley,or laminarly flowed in the extensive flatland.
The extremely rapid and long run-out landslides triggered by the Wenchuan Earthquake were occurred along the Yingxiu-Gaochuan-Beichuan-Nanba-Qingchuan of the main seismic fault.The estimated maximum sliding velocity is greater than 70m·s-1 under the over 1.5g earthquake acceleration,compared with conventional rainfall or liquefaction induced landslides.The run-out distance of landslide-debris is several or several ten times of the rockmass length from crown to exit due to the air layer lubrication in where lots of landslide dams occurred.The maximum run-out distance is 3200m.The three cases are studied from the Niuquangou rockslide-debris flow at the south west segment of the main seismic fault(Yingxiu,Wenchuan),the Chengxi rockslide at the middle segment of the main seismic fault(Beichuan) and the Donghekou rockslide-debris flow at the north east segment of the main seismic fault.The three cases illustrates following common characteristics:(1)parent rockmass is broken under long geologic processing and weathered;(2) Rockmass was separately expanded and thrown under long-period strong ground vibration in which the vertical motion was predominant along the main seismic fault;(3)sliding mass was crashed at the exiting zone and transferred to fragment material;(4) The secondary landslide was triggered underneath the exiting zone due to the powerful crashing and shaving processes that provides more mass to debris body and cushion shape;(5) The a long run-out distance fragment flow is occurred under air layer lubrication.The air layer was pressed and turbulently flowed in the narrow-shaped valley,or laminarly flowed in the extensive flatland.
引文
[1]姜云等.华蓥山溪口滑坡—碎屑流[J].地质灾害与环境保护,1992,3(2):51~58.Jiang Yun,et al.Rockslide-debris flowof the Xikou,Huaying,Sichuan.Geological Hazards and Environment Protection,1992,3(2):51~58.
[2]金德镰等.柘溪水库塘岩光滑坡.中国典型滑坡研究[M].北京:科学出版社,1988,301~305.Jing Delian,et al..The Tangyanguang landslide at the Zexi reser-voir.In:Researches on the Selected Cases of Landslides in Chi-na.Beijing:Science Press,1988,301~305.
[3]刘伟.西藏易贡巨型超高速远程滑坡地质灾害链特征研析[J].中国地质灾害与防治学报,2002,13(3):9~18.Liu Wei.Study on the characteristics of huge scale super highspeedlong distance landslide Chain in Yigong,Tibet.The Chinese Journalof Geological Hazard and Control,2002,13(3):9~18.
[4]唐川.昭通头寨沟特大型灾害性滑坡研究[J].云南地理环境研究,1991,3(2):64~71.Tang Chuan.A study on large-scale catastrophic landslide atTouzai gully of Zhaotong.Yun Geographic Environment Research,1991,3(2):64~71.
[5]邢爱国,高广运,吴世明..高速滑坡飞行气动特性的风洞试验研究[J].同济大学学报,2002,30(5):435~836.Xing Aiguo,et al..Study on wind tunnel testing of aero dynamicproperties of high speed landslide flying.Journal of Tongji Univer-sity,2002,30(5):435~836.
[6]徐峻岭.略论高速远程型坡体运动[J].中国地质灾害与防治学报,1993,4(4):1~6.Xu Junling.A brief discussion about slope movement with highspeed and long distance.The Chinese Journal of Geological Haz-ards and Control,1993,4(4):1~6.
[7]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433~444.Yin Yueping.Researches on the geo-hazards triggered by Wen-chuan earthquake,Sichuan.Journal of Engineering Geology,2008,16(4):433~444.
[8]殷跃平.汶川八级地震滑坡触发特征研究[J].工程地质学报,2009,16(1):29~38.Yin Yueping.Features of landslides triggered by the WenchuanEarthquake,Journal of Engineering Geology,2009,16(1):29~38.
[9]詹峥.洒勒山滑坡分析[J].山地研究,1986,4(3):145~152.Zhan Zheng,et al.Analysisi on Saleshan Landslide.MountainResearch,1986,4(3):145~152.
[10]George Plafker.Nevados Huascaran Avalanche.In:Voight B.Rockslide and Avalaches,Natural Phenomena[M].New York:Elsevier,1978,1:1~826.
[11]Hungr O.Dynamics of Rapid Landslides.In:Kyoji Sassa(eds)Landslides in Progress.Springer:2004,47~57.
[12]International Union of Geological Sciences Working Group onLandslide.A suggested method for describing the rate of move-ment of a landslide.Bulletin of the International Association ofEngineering Geology,1995,(52):75~78.
[13]Sassa K.,et al..Earthquake-induced-landslides:Distribution,motion and mechanisms.Soil and Foundations,(Special Issue forthe great Hanshin Earthquake Disasters)1996,53~64.
[14]Shreve R.L.Leaking and fluidization in air layer lubricated ava-lanches.Geol Soc American Bulletin,1968,(79):653~657.
[15]Seed H.B.Landslides during earthquakes due to soil liquefac-tion.ASCE,1968,94(SM5):1055~1122.
[2]金德镰等.柘溪水库塘岩光滑坡.中国典型滑坡研究[M].北京:科学出版社,1988,301~305.Jing Delian,et al..The Tangyanguang landslide at the Zexi reser-voir.In:Researches on the Selected Cases of Landslides in Chi-na.Beijing:Science Press,1988,301~305.
[3]刘伟.西藏易贡巨型超高速远程滑坡地质灾害链特征研析[J].中国地质灾害与防治学报,2002,13(3):9~18.Liu Wei.Study on the characteristics of huge scale super highspeedlong distance landslide Chain in Yigong,Tibet.The Chinese Journalof Geological Hazard and Control,2002,13(3):9~18.
[4]唐川.昭通头寨沟特大型灾害性滑坡研究[J].云南地理环境研究,1991,3(2):64~71.Tang Chuan.A study on large-scale catastrophic landslide atTouzai gully of Zhaotong.Yun Geographic Environment Research,1991,3(2):64~71.
[5]邢爱国,高广运,吴世明..高速滑坡飞行气动特性的风洞试验研究[J].同济大学学报,2002,30(5):435~836.Xing Aiguo,et al..Study on wind tunnel testing of aero dynamicproperties of high speed landslide flying.Journal of Tongji Univer-sity,2002,30(5):435~836.
[6]徐峻岭.略论高速远程型坡体运动[J].中国地质灾害与防治学报,1993,4(4):1~6.Xu Junling.A brief discussion about slope movement with highspeed and long distance.The Chinese Journal of Geological Haz-ards and Control,1993,4(4):1~6.
[7]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433~444.Yin Yueping.Researches on the geo-hazards triggered by Wen-chuan earthquake,Sichuan.Journal of Engineering Geology,2008,16(4):433~444.
[8]殷跃平.汶川八级地震滑坡触发特征研究[J].工程地质学报,2009,16(1):29~38.Yin Yueping.Features of landslides triggered by the WenchuanEarthquake,Journal of Engineering Geology,2009,16(1):29~38.
[9]詹峥.洒勒山滑坡分析[J].山地研究,1986,4(3):145~152.Zhan Zheng,et al.Analysisi on Saleshan Landslide.MountainResearch,1986,4(3):145~152.
[10]George Plafker.Nevados Huascaran Avalanche.In:Voight B.Rockslide and Avalaches,Natural Phenomena[M].New York:Elsevier,1978,1:1~826.
[11]Hungr O.Dynamics of Rapid Landslides.In:Kyoji Sassa(eds)Landslides in Progress.Springer:2004,47~57.
[12]International Union of Geological Sciences Working Group onLandslide.A suggested method for describing the rate of move-ment of a landslide.Bulletin of the International Association ofEngineering Geology,1995,(52):75~78.
[13]Sassa K.,et al..Earthquake-induced-landslides:Distribution,motion and mechanisms.Soil and Foundations,(Special Issue forthe great Hanshin Earthquake Disasters)1996,53~64.
[14]Shreve R.L.Leaking and fluidization in air layer lubricated ava-lanches.Geol Soc American Bulletin,1968,(79):653~657.
[15]Seed H.B.Landslides during earthquakes due to soil liquefac-tion.ASCE,1968,94(SM5):1055~1122.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心