震区急陡沟道型泥石流特征及动力过程研究——以汶川瓦窑沟为例
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摘要
汶川地震以来,汶川震区暴发了大量各种类型的泥石流,其中存在一种急陡沟道型泥石流.文章首先分析了急陡沟道型泥石流具有流域面积小、纵坡陡、物源储量丰富、侵蚀强烈及冲出规模大等特点;再以汶川县瓦窑沟为典型代表,采用FLO-2D软件模拟再现50年一遇暴雨频率下瓦窑沟泥石流的动力过程,研究其动力特性及启动、侵蚀、堆积演化过程.模拟结果显示,瓦窑沟急陡沟道型泥石流下游普遍淤高3~5 m,最大流速达9.34 m/s,与调查结果较为符合,表现出冲於幅度大、水动力强的特点.因此,应该开展对震区急陡沟道型泥石流风险评估、监测、早期预警等研究,同时应对治理工程方案需进行有效的组合.
After Wenchuan earthquake,a large number of various types of debris flow occurred in Wenchuan earthquake region.Firstly,the paper analyzed the characteristics of urgent steep gully debris flow,such as small catchment area,large longitudinal gradient,abundant loose materials,strong erosion and the large run-out scale.Then taking Wayao gully as a typical example,the basic characteristics and formation conditions were identified.Using FLO-2 D software,a simulation of the dynamical process of urgent-steep channels featured debris flow during 50-year rainstorm conditions was set up. The paper analysed dynamic characteristics,initiation,erosion and deposition of debris flow in Wayao gully.The results show that the depositions of downstream are generally 3—5 meters high and the maximum velocity is 9.34 m/s.The amplitude of scour and accumulation is large and the hydrodynamic force is strong.Therefore it is important to assess debris flow risk and take hazard monitoring and early warning for debris flows with urgent channels in the earthquake areas.The effective combination of control work is also necessary for debris flow hazard mitigation.
After Wenchuan earthquake,a large number of various types of debris flow occurred in Wenchuan earthquake region.Firstly,the paper analyzed the characteristics of urgent steep gully debris flow,such as small catchment area,large longitudinal gradient,abundant loose materials,strong erosion and the large run-out scale.Then taking Wayao gully as a typical example,the basic characteristics and formation conditions were identified.Using FLO-2 D software,a simulation of the dynamical process of urgent-steep channels featured debris flow during 50-year rainstorm conditions was set up. The paper analysed dynamic characteristics,initiation,erosion and deposition of debris flow in Wayao gully.The results show that the depositions of downstream are generally 3—5 meters high and the maximum velocity is 9.34 m/s.The amplitude of scour and accumulation is large and the hydrodynamic force is strong.Therefore it is important to assess debris flow risk and take hazard monitoring and early warning for debris flows with urgent channels in the earthquake areas.The effective combination of control work is also necessary for debris flow hazard mitigation.
引文
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[11]贾涛,唐川,王纳纳.基于FLO-2D与冲量模型的泥石流危险度分区方法及应用[J].水电能源科学,2015(2):152-155.JIA T,TANG C,WANG N N.Method and application of debris flow hazard zoning based on FLO-2D and impulse model[J].Water Resources and Power,2015(2):152-155.
[12]方群生,唐川.汶川8.0级地震震区溃决型和一般型泥石流冲出量研究[J].灾害学,2016,31(1):66-71.FANG Q S,TANG C.Study on run-out amount of break and general debris flows in Wenchuan earthquake area[J].Journal of Catastrophology,2016,31(1):66-71.
[13]GRIFFITHS P G,WEBB R H,MELIS T S.Initiation and frequency of debris flows in grand canyon,arizona[J].Journal of Geophysical Research Atmospheres,2004,109:321-336.
[2]TANG C,ZHU J,LI W L,et al.Rainfall-triggered debris flows following the Wenchuan earthquake[J].Bull Eng Geol Environ,2009,68:187-194.
[3]唐川.汶川地震区暴雨滑坡泥石流活动趋势预测[J].山地学报,2010,28(3):341-349.TANG C.Activity Tendency Prediction of Rainfall Induced Landslides and Debris Flows in the Wenchuan Earthquake Areas[J].Journal of Mountain Science,2010,28(3):341-349.
[4]TANG C,RENGERS N,VAN A C J.Triggering conditions and depositional characteristics of a disastrous debris flow event in Zhouqu city,Gansu Province,northwestern China[J].Hazards Earth Syst,2011,11:2 903-2 912.
[5]TANNG C,ZHU J,DING J.Catastrophic debris flows triggered by a 14 August 2010 rainfall at the epicenter of the Wenchuan earthquake[J].Landslides,2011,8(4):485-497.
[6]CUI P,XIANG L,ZOU Q.Risk assessment of highways affected by debris flows in Wenchuan earthquake area[J].Journal of Mountain Science,2013,10(2):173-189.
[7]杨东旭,游勇,陈晓清,等.汶川震区狭陡型泥石流典型特征与防治[J].水文地质工程地质,2015,42(1):146-153.YANG D X,YOU Y,CHEN X Q,et al.Typical characteristics and mitigation of debris flow in narrow-steep gullies in the Wenchuan earthquake areas[J].Hydrogeology&Engineering Geology,2015,42(1):146-153.
[8]胡卸文,韩玫,梁敬轩,等.汶川地震灾区泥石流若干关键问题[J].西南交通大学学报,2016,51(2):331-340.HU X W,HAN M,LIANG J X,et al.Some key problems on debris flow in wenchuan earthquake area[J].Journal of Southwest Jiaotong University,2016,51(2):331-340.
[9]崔鹏,庄建琦,陈兴长,等.汶川地震区震后泥石流活动特征与防治对策[J].四川大学学报:工程科学版,2010,42(5):10-19.CUI P,ZHUANG Q J,CHEN X C,et al.Activity characteristics and Prevention countermeasures of debris flow after“5.12”Wenchuan devastating earthquake[J].Journal of Sichuan University:Engineering Sciences Edition,2010,42(5):10-19.
[10]四川省冶金地质勘查局.国道G213线瓦窑沟泥石流应急勘查报告[R].成都:成都地质调查所,2013.Metallurgical Geological Prospecting Bureau of Sichuan Province.G213 national highway emergency investigation report of Wayao debris flow[R].Chengdu:Chengdu Geological Survey,2013.
[11]贾涛,唐川,王纳纳.基于FLO-2D与冲量模型的泥石流危险度分区方法及应用[J].水电能源科学,2015(2):152-155.JIA T,TANG C,WANG N N.Method and application of debris flow hazard zoning based on FLO-2D and impulse model[J].Water Resources and Power,2015(2):152-155.
[12]方群生,唐川.汶川8.0级地震震区溃决型和一般型泥石流冲出量研究[J].灾害学,2016,31(1):66-71.FANG Q S,TANG C.Study on run-out amount of break and general debris flows in Wenchuan earthquake area[J].Journal of Catastrophology,2016,31(1):66-71.
[13]GRIFFITHS P G,WEBB R H,MELIS T S.Initiation and frequency of debris flows in grand canyon,arizona[J].Journal of Geophysical Research Atmospheres,2004,109:321-336.