汶川地震引发高速远程滑坡运动机理数值模拟研究——以谢家店子滑坡为例
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摘要
针对汶川地震引发的谢家店子滑坡,在现场调查分析的基础上,建立了二维离散元数值模拟模型,采用2D-Block软件对其进行了全过程的数值模拟研究,并通过对跟踪块体的深入分析,研究了相应地质体在不同阶段下的运动特征。模拟结果表明,谢家店子滑坡经历了剧动启程抛掷阶段、快速撞击飞行阶段、铲刮减速碎屑流阶段及堆积掩埋阶段。为了揭示地震引发高速滑坡的发生规律,分别研究了地震震级、斜坡地形和斜坡上岩块的尺寸对高速滑坡启动和运动过程的影响规律。地震震级对边坡的启动、变形、破坏和运动有很大的影响,地震震级越大,滑体启动的加速度和速度也就越大,从而易形成高速远程滑坡。斜坡体本身的地形地貌对滑体运动也有较大影响。在震级和岩石力学参数一定的条件下,斜坡上岩块的大小对其启动、变形和运动过程有一定影响,随着岩块的增大,滑体运动的每个阶段历时都在减小,但当岩体十分破碎时,滑体虽然能够运动,但是很难发生抛掷。将地震滑坡的启动机理概括为积累变形效应、振荡启程效应和振荡加速效应。
In view of Xiejiadianzi highspeed and long runout landslide caused by Wenchuan Earthquake,based on the investigation and analysis on the spot,a two-dimension discrete element numerical simulation model was built,numerical simulation was done by 2D-Block software.Furthermore,motion characteristics of corresponding geologic body at different stages through the thorough analysis of tracking block were discussed.The results indicated that Xiejiadianzi landslide experienced four periods: the instantaneously sliding stage,the intensive colliding cushion stage,the scraping slow down stage and the deposit stage.In order to reveal the occurence regularity of highspeed landslide triggered by Wenchuan Earthquake,the influence laws of three factors including earthquake magnitude,the topography of landslope and the size of rockmass on the landslope to the highspeed landslide were studied.Earthquake magnitude had great influence on the set-out,deformation and destruction and movement of landslope.The greater the earthquake magnitude,the faster the accelerated speed and speed of the sliding,the easier of forming high speed and long runout landslide.The topography of slope also had greater effect on the movement of the sliding mass.Under the certain magnitude and rock mechanics parameters,the size of the rockmass on the landslope had a certain effect on the set-out,deformation and destruction and movement of landslope.With the increasing of the size of rockmass,the speed of the sliding decreased in each stage.However,when the rockmass was broken,it was hard to cast for the sliding movement although it could move.The set-out mechanisms of landslide were summarized as three effects: the progressive and deformation effect,the set-out effect and the acceleration effect.
In view of Xiejiadianzi highspeed and long runout landslide caused by Wenchuan Earthquake,based on the investigation and analysis on the spot,a two-dimension discrete element numerical simulation model was built,numerical simulation was done by 2D-Block software.Furthermore,motion characteristics of corresponding geologic body at different stages through the thorough analysis of tracking block were discussed.The results indicated that Xiejiadianzi landslide experienced four periods: the instantaneously sliding stage,the intensive colliding cushion stage,the scraping slow down stage and the deposit stage.In order to reveal the occurence regularity of highspeed landslide triggered by Wenchuan Earthquake,the influence laws of three factors including earthquake magnitude,the topography of landslope and the size of rockmass on the landslope to the highspeed landslide were studied.Earthquake magnitude had great influence on the set-out,deformation and destruction and movement of landslope.The greater the earthquake magnitude,the faster the accelerated speed and speed of the sliding,the easier of forming high speed and long runout landslide.The topography of slope also had greater effect on the movement of the sliding mass.Under the certain magnitude and rock mechanics parameters,the size of the rockmass on the landslope had a certain effect on the set-out,deformation and destruction and movement of landslope.With the increasing of the size of rockmass,the speed of the sliding decreased in each stage.However,when the rockmass was broken,it was hard to cast for the sliding movement although it could move.The set-out mechanisms of landslide were summarized as three effects: the progressive and deformation effect,the set-out effect and the acceleration effect.
引文
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[7]刘红岩,王明.节理岩质边坡稳定性的离散元分析[J].金属矿山,2008(9):15-18.
[8]毛彦龙,胡广韬,毛新虎,等.地震滑坡启程剧动的机理研究及离散元模拟[J].工程地质学报,2001,9(1):74-80.
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[11]Chandra U.Attenuation of Intensities in the United States[J].Bulletin of the Seismological Society of America,1979,69(6):2003-2024.
[2]彭建兵,马润勇,范文,等.汶川大震的科学思考[J].地球科学与环境学报,2009,31(1):1-29.
[3]黄润秋,李为乐.汶川大地震触发地质灾害的断层效应分析[J].工程地质学报,2009,17(1):19-28.
[4]王涛,马寅生,龙长兴,等.四川汶川地震断裂活动和次生地质灾害浅析[J].地质通报,2008,27(11):1913-1922.
[5]伍法权,胡瑞林,岳中琦,等.5.12汶川地震地质灾害[M].北京:地质出版社,2009.
[6]徐锡伟,闻学泽,叶建青,等.汶川Ms8.0地震地表破裂带及其发震构造[J].地震地质,2008,30(3):597-629.
[7]刘红岩,王明.节理岩质边坡稳定性的离散元分析[J].金属矿山,2008(9):15-18.
[8]毛彦龙,胡广韬,毛新虎,等.地震滑坡启程剧动的机理研究及离散元模拟[J].工程地质学报,2001,9(1):74-80.
[9]陈晓兰,卢国胜.地震诱发滑坡的机理研究[J].安徽农业科学,2009,37(18):8612-8613.
[10]Battis J.Regional Modification of Acceleration AttenuationFunctions[J].Bulletin of the Seismological Society of America,1981,71(4):1309-1321.
[11]Chandra U.Attenuation of Intensities in the United States[J].Bulletin of the Seismological Society of America,1979,69(6):2003-2024.
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