汶川震区暴雨泥石流激发雨型特征
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摘要
汶川地震后暴雨诱发的泥石流不断增加,通过收集整理降雨资料,分析汶川震区不同地域泥石流暴发的激发雨强及前期有效累计降雨量变化过程,揭示震区暴雨泥石流的激发雨型特征,为暴雨泥石流的预报提供科学依据。研究结果表明,汶川震区的暴雨泥石流激发雨型可分为短期突然降雨型、中期持续降雨型和长期间断降雨型3种类型,主要表现为引发泥石流的激发雨强及前期有效累计降雨量的不同。暴雨泥石流的形成机制体现为降雨导致流域内松散土体渗透、饱和及侵蚀移动的过程。激发雨型与激发雨强及前期有效累计降雨量存在相关关系,短期突然降雨型的激发雨强最大,前期有效累计降雨量最少;中期持续降雨型的激发雨强居中,前期有效累计降雨量最多;长期间断降雨型的激发雨强最小,前期有效累计降雨量居中。对四川茂县叠溪镇新磨村突发山体高位垮塌碎屑流进行验证,初步判定是由长期间断降雨型引发岩体抗剪强度降低而引起的。对不同激发雨型特征的研究能够为汶川震区泥石流监测预警提供科学依据。
To obtain the rainfall characteristics and enhance the early warning system for rainfall-induced debris flows,the post-debris flow rainfall data in the Wenchuan earthquake area are collected,and the rainfall intensity and early-stage effective accumulative rainfall are analyzed. The results show that the rainfall-induced debris flows in the study area can be classified into three types,i. e.,short-term rainfall,persistent rainfall and intermittent rainfall. The main differences among the three rainfall types occur in the rainfall intensity,duration and effective accumulation,which can result in different soil percolation,saturation,and erosion mechanisms in provenance for debris flow initiation. Critical rainfall intensities and effective accumulative rainfall could be related to critical rainfall types. The short-term rainfall type may be associated with the highest rainfall intensityand the least effective accumulation; persistent rainfall type is associated with medium rainfall intensity and the most effective accumulation,whilst the intermittent rainfall type can be related to the lowest rainfall intensity and the medium effective accumulation. After a verification for the sudden collapse induced by the high-mountain-formation debris flows in Xinmo Village of the study area,the result showed that the prime reason was the decrease of rock shear strength caused by long-term intermittent rainfall. This work provides scientific basis for the early warning system for debris flows in the Wenchuan earthquake area.
To obtain the rainfall characteristics and enhance the early warning system for rainfall-induced debris flows,the post-debris flow rainfall data in the Wenchuan earthquake area are collected,and the rainfall intensity and early-stage effective accumulative rainfall are analyzed. The results show that the rainfall-induced debris flows in the study area can be classified into three types,i. e.,short-term rainfall,persistent rainfall and intermittent rainfall. The main differences among the three rainfall types occur in the rainfall intensity,duration and effective accumulation,which can result in different soil percolation,saturation,and erosion mechanisms in provenance for debris flow initiation. Critical rainfall intensities and effective accumulative rainfall could be related to critical rainfall types. The short-term rainfall type may be associated with the highest rainfall intensityand the least effective accumulation; persistent rainfall type is associated with medium rainfall intensity and the most effective accumulation,whilst the intermittent rainfall type can be related to the lowest rainfall intensity and the medium effective accumulation. After a verification for the sudden collapse induced by the high-mountain-formation debris flows in Xinmo Village of the study area,the result showed that the prime reason was the decrease of rock shear strength caused by long-term intermittent rainfall. This work provides scientific basis for the early warning system for debris flows in the Wenchuan earthquake area.
引文
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[21]余天彬,任光明,王猛,等.汶川震区龙门山镇高架子沟“8·18”泥石流灾害机理与特征[J].中国地质灾害与防治学报,2014,25(3):9-13.
[22]ZHOU W,TANG C,ZHOU C H.Critical rainfall characteristics for rainfall-induced debris flows in Wenchuan earthquake affected areas[J].Advances in Water Science,2012,23(5):650-655.
[23]吴雨夫,余斌,亓星,等.岷江上游大白杨沟泥石流特征及成因[J].现代地质,2012,26(1):107-113.
[2]PRETE M D,GUADAGNO F M,HAWKINS A B.Preliminary report on the landslides of 5 May 1998,Campania,southern Italy[J].Bulletin of Engineering Geology&the Environment,1998,57(2):113-129.
[3]KHAZAI B,SITAR N.Evaluation of factors controlling earthquake-induced landslides caused by Chi-Chi earthquake and comparison with the Northridge and Loma Prieta events[J].Engineering Geology,2004,71(1):79-95.
[4]HUANG B S,CHEN K C,HUANG W G,et al.Characteristics of strong ground motion across a thrust fault tip from the September 21,1999,Chi-Chi,Taiwan earthquake[J].Geophysical Research Letter,2000,27(17):2729-2732.
[5]SHIN T C.An overview of the 1999 Chi-Chi,Taiwan,earthquake[J].Bulletin of the Seismological Society of America,2001,91(5):895-913.
[6]TANG C,ZHU J,LI W L,et al.Rainfall-triggered debris flows following the Wenchuan earthquake[J].Bulletin of Engineering Geology&the Environment,2009,68(2):187-194.
[7]常鸣,唐川,蒋志林,等.强震区都江堰市龙池镇泥石流物源的遥感动态演变[J].山地学报,32(1):89-97.
[8]CUI P,HU K,ZHUANG J,et al.Prediction of debris-flow danger area by combining hydrological and inundation simulation methods[J].Journal of Mountain Science,2011,8(1):1-9.
[9]温铭生,方志伟,王阳谷.都江堰市五里坡特大滑坡灾害特征与致灾成因[J].现代地质,2015,29(2):448-453.
[10]NI H,WANG D.Present status,problem and advice on the research of prediction and forecasting of debris flow based on rainfall condition[J].Journal of Catastrophology,2010,25(1):124-128.
[11]ZHOU W,TANG C,ASCH T W J V,et al.Rainfall-triggering response patterns of post-seismic debris flows in the Wenchuan earthquake area[J].Nature Hazards,2014,70(2):1417-1435.
[12]王涛,余斌,亓星,等.贵州望谟纳包沟泥石流特征及成因分析[J].现代地质,2013,27(3):727-732.
[13]郭晓军,崔鹏,马力,等.都汶公路沿线诱发泥石流的降雨特征[J].山地学报,2014,32(6):739-746.
[14]崔鹏,韦方强,何思明,等.5·12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.
[15]常鸣,唐川,李为乐,等.汶川地震区绵远河流域泥石流形成区的崩塌滑坡特征[J].山地学报,2012,30(5):561-569.
[16]唐川,李为乐,丁军,等.汶川震区映秀镇“8·14”特大泥石流灾害调查[J].地球科学,2011,36(1):172-180.
[17]周伟,唐川,周春花.汶川震区暴雨泥石流激发雨量特征[J].水科学进展,2012,23(5):650-655.
[18]YU B,MA Y,WU Y F.Investigation of severe debris flow hazards in Wenjia gully of Sichuan province after the Wenchuan earthquake[J].Journal of Engineering Geology,2010,18(6):827-836.
[19]胡卸文,吕小平,黄润秋,等.唐家山堰塞坝“9·24”泥石流堵江及溃决模式[J].西南交通大学学报,2009,44(3):312-320.
[20]CHANG M,TANG C,ZHANG D D,et al.Debris Flow Susceptibility Assessment Using a Probabilistic Approach:A Case Study in the Longchi Area,Sichuan Province,China[J].Journal of Mountain Science,2014,11(4):1001-1014.
[21]余天彬,任光明,王猛,等.汶川震区龙门山镇高架子沟“8·18”泥石流灾害机理与特征[J].中国地质灾害与防治学报,2014,25(3):9-13.
[22]ZHOU W,TANG C,ZHOU C H.Critical rainfall characteristics for rainfall-induced debris flows in Wenchuan earthquake affected areas[J].Advances in Water Science,2012,23(5):650-655.
[23]吴雨夫,余斌,亓星,等.岷江上游大白杨沟泥石流特征及成因[J].现代地质,2012,26(1):107-113.