东河口滑坡-碎屑流高速远程运移机制探讨
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摘要
青川东河口滑坡-碎屑流是"5.12"汶川大地震触发的典型高速远程滑坡,滑坡自高程1300m处开始滑动,总滑程约2400m,致使780余人遇难。野外调研结果表明,该滑坡自启动到最终静止,分别经历了滑坡启动阶段、重力加速阶段、圈闭气垫效应飞行阶段、撞击折返阶段及长距离滑动堆积阶段5个重要动力过程,最终抵达下寺河左岸的红花地村并形成堰塞湖。文中通过对该高速远程滑坡-碎屑流的地质背景及形态特征进行剖析认为,东河口滑坡启动区的断层破碎带、局部凸起地形以及力学性质较差的千枚岩、板岩的存在,对该滑坡的启动均有着显著影响;滑坡体在运行一段距离后是否可以继续保持高速远程滑动,除了有利的地形外,滑体滑动路径上高含水量的溪流堆积物的存在,是促使该滑坡成为高速远程滑坡-碎屑流的重要原因之一。
The Donghekou landslide-debris flow is a typical rapid long run-out landslide triggered by the great Wenchuan earthquake. It started from the elevation of 1300 m and caused 780 deaths,with a total long run-out of 2400 m. Field investigations show that,during the sliding process from start-up to stop,this landslide-debris flow experienced the following five dynamical stages. They are the starting-up stage,the gravity speed-up stage,the enclosure air cushion effect stage,the impact reentry stage and the long run-out sliding accumulation stage. Finally,the debris reached the Honghuadi village,which is located at the left bank of the Xiasihe River,causing the formation of dammed lakes. By analyzing the geological setting and feature of this landslide-debris flow,this paper draws a conclusion that the initiation of Donghekou landslide-debris flow is mainly affected by the fault crush belt,the local convex landform and the phyllite and carbon slate with weak mechanical property. For the rapid and long run-out sliding of this landslide-debris flow,the water containing condition of the slope debris on sliding route is an important factor,besides the advantage landform.
The Donghekou landslide-debris flow is a typical rapid long run-out landslide triggered by the great Wenchuan earthquake. It started from the elevation of 1300 m and caused 780 deaths,with a total long run-out of 2400 m. Field investigations show that,during the sliding process from start-up to stop,this landslide-debris flow experienced the following five dynamical stages. They are the starting-up stage,the gravity speed-up stage,the enclosure air cushion effect stage,the impact reentry stage and the long run-out sliding accumulation stage. Finally,the debris reached the Honghuadi village,which is located at the left bank of the Xiasihe River,causing the formation of dammed lakes. By analyzing the geological setting and feature of this landslide-debris flow,this paper draws a conclusion that the initiation of Donghekou landslide-debris flow is mainly affected by the fault crush belt,the local convex landform and the phyllite and carbon slate with weak mechanical property. For the rapid and long run-out sliding of this landslide-debris flow,the water containing condition of the slope debris on sliding route is an important factor,besides the advantage landform.
引文
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[14]王家鼎,张倬元.地震诱发高速黄土滑坡的机理研究[J].岩土工程学报,1999,6(21):670～674.Wang Jiading,Zhang Zhuoyuan.A study on the mechanism of high speed loess landslide induced by earthquake[J].Chinese Journal of Geotechnical Engineering,1999,6(21):670～674.
[15]孙萍,殷跃平,吴树仁等.干湿状态下东河口滑坡岩石抗剪断性质试验研究[J].地质通报,2009,28(8):1163～1167.Sun Ping,Yin Yueping,Wu Shuren,et al..Experimental Study on Shear Strength of Rocks from Donghekou Landslide in Dried State and Saturated State[J].Geological Bulletin of China,2009,28(8):1163～1167.
[16]孙萍,殷跃平,吴树仁等.高速远程地震黄土滑坡发生机制试验研究[J].工程地质学报,2009,17(4):449～454.Sun Ping,Yin Yueping,Wu Shuren,et al..An experimental study on the initiation mechanism of rapid and long run-out lo-ess landslide triggered by earthquake.Hydrogeology and Engi-neering Geology,2009,17(4):449～454.
[2]Schreve R.L.Leaking and fluidization in air layer lubricated ava-lanches.Geol Soc American Bulletin.1968,79:654～758.
[3]Keefer D.V.Landslides caused by earthquakes[J].Geological Society of America Bulletin,1984,95(4):406～421.
[4]Papadopoulos G.A.and Plessa A..Magnitude-distance relations for earthquake-induced landslide in Greece[J].Engineering Ge-ology,Special Issue,2000,(58):377～386.
[5]Prestininzi A.and Romeo R..Earthquake-induced ground failures in Italy[J].Engineering Geology,Special Issue,2000,(58):387～397.
[6]Sassa K,Wang G,Fukoka H,Wang F,Ochiai T,Sugiyama M,Sekiguchi T.Landslide risk evaluation and hazard zoning for rapid and long-travel landslides in urban development areas.Land-slides,2004,1(3):221～235.
[7]Scheidegger,A.E.On the prediction of the reaching and velocity of catastrophic landslides[J].RockMechanics,1973,(5):231～23.
[8]汪发武.高速滑坡形成机制:土粒子破碎导致超孔隙水压力的产生[J].长春科技大学学报,2001,1(31):64～69.Wang Fawu.Mechanism of rapid landslides:excess pore pressure generation caused by grain crushing.Journal of Changchun univer-sity of science and technology,2001,1(31):64～69.
[9]胡广韬,等.滑坡动力学[M].北京:地质出版社,1995.Hu Guang-Tao,et al..Landslide Dynamics.Beijing:Geology Press,1995.
[10]王思敬,王效宁.大型高速滑坡的能量分析及其灾害预测[A].全国滑坡学术讨论会滑坡论文选集[C].成都:四川科学技术出版社,1989,117～124.Wang Sijing,Wang Xiaoning.Analysis of energy on large-scale high speed landslide and their catastrophic prediction.In:Se-lected Papers on Landslide.Chengdu:Sichuan Science and Technology Press,1989,117～124.
[11]殷跃平.汶川八级地震滑坡高速远程特征分析[J].工程地质学报,2009,17(2):153～164.Yin Yueping.Papid and long run-out features of landslides trig-gered bu the Wenchuan earthquake.Journal of Engineering Geol-ogy,2009,17(2):153～164.
[12]殷跃平.西藏波密易贡高速巨型滑坡特征及减灾对策[J].水文地质工程地质,2000,(4):8～11.Yin Yueping.Rapid huge landslide and hazard reduction of Yigong River in the Bomi Tibet.Hydrogeology and Engineering Geology,2000,(4):8～11.
[13]崔芳鹏,胡瑞林,张明等.重庆小南海地震崩滑体的基本特征及形成机制研究[J].工程地质学报,2009,17(2):167～174.Cui Fangpeng,Hu Ruilin,Zhang Ming,et al..Basic character-istics and formation mechanism of collapse and slided debris mass induced by Xiaonanhai earthquake in Chongqing city.Journal of Engineering Geology2009,17(2):167～174.
[14]王家鼎,张倬元.地震诱发高速黄土滑坡的机理研究[J].岩土工程学报,1999,6(21):670～674.Wang Jiading,Zhang Zhuoyuan.A study on the mechanism of high speed loess landslide induced by earthquake[J].Chinese Journal of Geotechnical Engineering,1999,6(21):670～674.
[15]孙萍,殷跃平,吴树仁等.干湿状态下东河口滑坡岩石抗剪断性质试验研究[J].地质通报,2009,28(8):1163～1167.Sun Ping,Yin Yueping,Wu Shuren,et al..Experimental Study on Shear Strength of Rocks from Donghekou Landslide in Dried State and Saturated State[J].Geological Bulletin of China,2009,28(8):1163～1167.
[16]孙萍,殷跃平,吴树仁等.高速远程地震黄土滑坡发生机制试验研究[J].工程地质学报,2009,17(4):449～454.Sun Ping,Yin Yueping,Wu Shuren,et al..An experimental study on the initiation mechanism of rapid and long run-out lo-ess landslide triggered by earthquake.Hydrogeology and Engi-neering Geology,2009,17(4):449～454.