汶川震区文家沟泥石流成灾机理与特征
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摘要
文家沟位于绵竹市清平乡,属于5.12汶川M s8.0级地震极重灾区。地震发生后的3个汛期内,文家沟曾先后发生5次典型泥石流灾害,其中以2010年8月13日泥石流灾害最为严重,规模与灾情巨大,社会影响深远。在对文家沟泥石流跟踪调查的基础上,探讨了泥石流的成灾机理和特征。研究表明:(1)文家沟泥石流是地震和强降雨共同作用的结果,其成因可归纳为震因与物源以及雨因与水源两个方面,在整个泥石流形成和发生的过程中,呈现出洪流-侵蚀下切-崩滑-席卷-进一步侵蚀下切-进一步崩滑-增大泥石流规模—……的"滚雪球式"循环过程;(2)泥石流发生所需的雨量、雨强条件和水动力条件都显著降低,泥石流规模和雨量之间呈现出明显幂函数关系;(3)发生过程呈现出持续时间长、运动距离远的特征;(4)成灾过程呈现出明显的链式效应,危害形式多样;(5)泥石流频率呈现出高发性,规模呈现出放大性。最后提出了文家沟泥石流研究与防治的建议。
Wenjia gully is located at the epicenter area of the 2008 Wenchuan Earthquake.A huge landslide was ever triggered by the earthquake.During the passed three flood seasons,at least five typical debris flows occurred at Wenjia gully.In particular,a severest debris flow occurred on Aug.13,2010.It had a volume up to 3.1×107m3.Five residents lost their lives unfortunately and hundreds of new-built houses were buried during the catastrophic event.However,it was fortunate that almost all the residents evacuated successfully before the debris flow occurred.In this paper,on the basis of tracking investigation,the mechanism and characteristics of the Wenjia-gully debris flows were discussed and some suggestions were put forward.The acknowledges obtained after investigation and analysis are as follows:(1)The debris flows were caused by both Wenchuan earthquake and strong rainfall.As the debris flow formation is concerned,a circle was presented as runoff-erosion-collapse-engulfment-erosion-collapse-enlargement-,and so on;(2)The critical rainfall initiated debris flow was significantly decreased and a power-law relation is existed between debris flow magnitude and daily rainfall,which can be used to predict the volume of debris flow on the basis of weather forecasting;(3)As the occurrence process is concerned,the debris flow lasted for a long duration and moved a far distance;(4)In terms of destroying process,a clear chain characteristic was taken on with several damage ways;(5)Debris flow magnitude was enlarged and the frequency was higher obviously.
Wenjia gully is located at the epicenter area of the 2008 Wenchuan Earthquake.A huge landslide was ever triggered by the earthquake.During the passed three flood seasons,at least five typical debris flows occurred at Wenjia gully.In particular,a severest debris flow occurred on Aug.13,2010.It had a volume up to 3.1×107m3.Five residents lost their lives unfortunately and hundreds of new-built houses were buried during the catastrophic event.However,it was fortunate that almost all the residents evacuated successfully before the debris flow occurred.In this paper,on the basis of tracking investigation,the mechanism and characteristics of the Wenjia-gully debris flows were discussed and some suggestions were put forward.The acknowledges obtained after investigation and analysis are as follows:(1)The debris flows were caused by both Wenchuan earthquake and strong rainfall.As the debris flow formation is concerned,a circle was presented as runoff-erosion-collapse-engulfment-erosion-collapse-enlargement-,and so on;(2)The critical rainfall initiated debris flow was significantly decreased and a power-law relation is existed between debris flow magnitude and daily rainfall,which can be used to predict the volume of debris flow on the basis of weather forecasting;(3)As the occurrence process is concerned,the debris flow lasted for a long duration and moved a far distance;(4)In terms of destroying process,a clear chain characteristic was taken on with several damage ways;(5)Debris flow magnitude was enlarged and the frequency was higher obviously.
引文
[1]崔鹏,韦方强,陈小清,等.汶川地震次生山地灾害及其减灾对策[J].中国科学院院刊,2008,23(4):317~323.Cui Peng,Wei Fangqiang,Chen Xiaoqing,et al.Geo-hazards inWenchuan-earthquake area and countermeasures for disaster reduc-tion.Bulletin of Chinese Academy of Sciences,2008,23(4):317~323.
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[8]唐川,铁永波.汶川震区北川县城魏家沟暴雨泥石流灾害调查分析[J].山地学报,2009,27(5):625~630.Tang Chuan,Tie Yongbo.Reconnaissance and analysis on the rain-storm induced debris flowin Weijiagou valley of Beichuan city afterthe Wenchuan earthquak.Journal of Mountain Science,2009,27(5):625~630.
[9]许强,裴向军,黄润秋,等.汶川地震大型滑坡研究[M].北京:科学出版社,2009,381~406.Xu Qiang,Pei Xiangjun,Huang Runqiu,et al.Large~scale land-slides induced by the Wenchuan earthquake.Beijing:SciencePress,2009,381~401.
[10]黄河清,赵其华.汶川地震诱发文家沟巨型滑坡-碎屑流基本特征及成因机制初步分析[J].工程地质学报,2010,18(2):168~177.Huang Heqing,Zhao Qihua.Basic characteristics and preliminarymechanism analysis of large scale rockslide-sturzstrom at Wenjia-gou triggered by Whenchun earthquake.Journal of EngineeringGeology,2010,18(2):168~177.
[11]王涛,石菊松,吴树仁,等.汶川地震触发文家沟高速远程滑坡-碎屑流成因机理分析[J].工程地质学报,2010,18(5):631~644.Wang Tao,Shi Jusong,Wu Shuren,et al.Formation mechanism ofWenjiagou high-speed and long-runout debris avalanche triggeredby Whenchun earthquake.Journal of Engineering Geology,2010,18(5):631~644.
[12]余斌,马煜,吴雨夫,等.汶川地震后四川省绵竹市清平乡文家沟泥石流灾害调查研究[J].工程地质学报,2010,18(6):827~836.Yu Bin,Ma Yu,Wu Yufu,et al.Investigation of severe debris flowhazards in Wenjia gully of Sichuan province after the Wenchuanearthquake.Journal of Engineering Geology,2010,18(6):827~836.
[13]谭万沛.泥石流及其灾害的极大值[J].灾害学,1987,2(3):79~83.Tan Wanpei.Maximum of debris flow and disaster.Journal ofCatastrophology,1987,2(3):79~83.
[2]唐川,梁京涛.汶川震区北川9.24暴雨泥石流特征研究[J].工程地质学报,2008,16(6):751~758.Tang Chuan,Liang Jingtao.Characterisitics of debris flows in Bei-chun epicenter of the Wenchuan earthquake triggered by rain stormon September 24,2008.Journal of Engineering,2008,16(6):751~758.
[3]谢洪,王士革,孔纪名.“5.12”汶川地震次生山地灾害的分布与特点[J].山地学报,2008,26(4):396~401.Xie Hong,Wang Shige,Kong Jiming.Distribution and characteris-tics of mountain hazards induced by the earthquake of May l2 inWenchuan,China.Journal of Mountain Science,2008,26(4):396~401.
[4]谢洪,钟敦伦,矫震,等.2008年汶川地震重灾区的泥石流[J].山地学报,2009,27(4):501~509.Xie Hong,Zhong Dunlun,Jiao Zhen,et al.Debris flow in Wen-chuan Quake-hit area in2008.Journal of Mountain Science,2009,27(4):501~509.
[5]崔鹏,韦方强,何思明,等.512汶川地震诱发的山地灾害及减灾措施[J].山地学报,2008,26(3):280~282.Cui Peng,Wei Fangqiang,He Siming,et al.Mountain disasters in-duced by the earthquake of May12 in Wenchuan and the disastersmitigation.Journal of Mountain Science,2008,26(3):280~282.
[6]Tang C,Zhu J,Li W L.Rainfall triggered debris flows after Wen-chuan earthquake.Bull Eng Geol Environ,2009,68:187~194.
[7]许强.四川省8.13特大泥石流灾害特点、成因与启示[J].工程地质学报,2010,18(5):610~621.Xu Qiang,The 13 August2010 catastrophic debris flowin Sichuanprovince:Characteristics,genetic mechanism and suggestion.Jour-nal of Engineering,2010,18(5):610~621.
[8]唐川,铁永波.汶川震区北川县城魏家沟暴雨泥石流灾害调查分析[J].山地学报,2009,27(5):625~630.Tang Chuan,Tie Yongbo.Reconnaissance and analysis on the rain-storm induced debris flowin Weijiagou valley of Beichuan city afterthe Wenchuan earthquak.Journal of Mountain Science,2009,27(5):625~630.
[9]许强,裴向军,黄润秋,等.汶川地震大型滑坡研究[M].北京:科学出版社,2009,381~406.Xu Qiang,Pei Xiangjun,Huang Runqiu,et al.Large~scale land-slides induced by the Wenchuan earthquake.Beijing:SciencePress,2009,381~401.
[10]黄河清,赵其华.汶川地震诱发文家沟巨型滑坡-碎屑流基本特征及成因机制初步分析[J].工程地质学报,2010,18(2):168~177.Huang Heqing,Zhao Qihua.Basic characteristics and preliminarymechanism analysis of large scale rockslide-sturzstrom at Wenjia-gou triggered by Whenchun earthquake.Journal of EngineeringGeology,2010,18(2):168~177.
[11]王涛,石菊松,吴树仁,等.汶川地震触发文家沟高速远程滑坡-碎屑流成因机理分析[J].工程地质学报,2010,18(5):631~644.Wang Tao,Shi Jusong,Wu Shuren,et al.Formation mechanism ofWenjiagou high-speed and long-runout debris avalanche triggeredby Whenchun earthquake.Journal of Engineering Geology,2010,18(5):631~644.
[12]余斌,马煜,吴雨夫,等.汶川地震后四川省绵竹市清平乡文家沟泥石流灾害调查研究[J].工程地质学报,2010,18(6):827~836.Yu Bin,Ma Yu,Wu Yufu,et al.Investigation of severe debris flowhazards in Wenjia gully of Sichuan province after the Wenchuanearthquake.Journal of Engineering Geology,2010,18(6):827~836.
[13]谭万沛.泥石流及其灾害的极大值[J].灾害学,1987,2(3):79~83.Tan Wanpei.Maximum of debris flow and disaster.Journal ofCatastrophology,1987,2(3):79~83.
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