汶川地震区绵竹小岗剑沟泥石流发展趋势
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摘要
小岗剑沟是汶川地震区内一条典型的泥石流沟,位于绵远河的左测,流域面积1.36 km2,沟床平均纵比降412‰。该沟在2008年"5.12"汶川地震后多次暴发泥石流,掩埋从沟口通过的汉(旺)清(平)公路,给四川省绵竹市清平乡的地震灾后重建造成重大危害。通过初步分析,小岗剑沟泥石流的形成过程为:暴雨作用下沟因上游良好的汇流条件而产生山洪→山洪冲刷堆积在沟道内的松散固体物质形成小规模泥石流→泥石流沿大比降沟道向下运动,因具有强大动能而具有强大冲刷下切侵蚀能力,下切侵蚀下游沟床质以及沟口的老台地→在沟口形成大规模泥石流。地震后4 a内共暴发泥石流10次,将沟口老堆积体下切侵蚀深度达35 m,泥石流冲出固体物质50×104m3。目前,沟内仍有固体物质量334.3×104m3,可能参与泥石流活动的动储量为156.8×104m3。如此大量的松散固体物源,使小岗剑沟可能还暴发大规模泥石流。通过泥石流形成因素分析,该沟泥石流活动总体呈强度下降趋势,泥石流活动类型:震后一段时间内为输移控制型、然后为输移控制型向松散固体物质控制型过渡,最后发展成为松散固体物质控制型。通过这些分析,为泥石流治理提供科学支撑。
The Xiaogangjian Gully is typical for debris flow in the earthquake zone.Located in the left of Mianyuan river,it has a drainage area of 1.36 km2 and an average longitudinal slope of 412‰.After Wenchuan earthquake,many debris flow occurred in this gully,causing great disasters to the reconstruction of Qingping town,The debris flow formation process is as follows: torrents→ torrent scourage → small-scale debris flow → debris flow in mainstream channel,with powerful energy and strong capacity of scouring →,incision of streambed sediment and old deposit platform → large-scale debris flow.at the outlet There were 10 debris flows in the following 4 years after the earthquake,which cut the gully up to the depth of 35 m,and brought 50 × 104 m3 of solid mass out of the gully.Debris flows buried the Hanwang-Qingping road,blocked the river and formed a dam lake,carried a huge volume of sediment to the downstream,uplifting the water level and silting the highway.At present,the gully still has 334.3×104 m3 of solid material,of which about 156.8×104 m is prone to debris flow in the future when it encounters great rainstorms.The development trends of the debris flow in Xiaogangjian gully are as follows: 1) its strength of activity will keep reducing with the decrease of loose granular materials and total amounts of debris flow;2) the debris-flow's activity is transport-limited system right after the earthquake,followed by the transitional type between transport-limited system and weathering-limited system and ultimately is weathering-limited system.
The Xiaogangjian Gully is typical for debris flow in the earthquake zone.Located in the left of Mianyuan river,it has a drainage area of 1.36 km2 and an average longitudinal slope of 412‰.After Wenchuan earthquake,many debris flow occurred in this gully,causing great disasters to the reconstruction of Qingping town,The debris flow formation process is as follows: torrents→ torrent scourage → small-scale debris flow → debris flow in mainstream channel,with powerful energy and strong capacity of scouring →,incision of streambed sediment and old deposit platform → large-scale debris flow.at the outlet There were 10 debris flows in the following 4 years after the earthquake,which cut the gully up to the depth of 35 m,and brought 50 × 104 m3 of solid mass out of the gully.Debris flows buried the Hanwang-Qingping road,blocked the river and formed a dam lake,carried a huge volume of sediment to the downstream,uplifting the water level and silting the highway.At present,the gully still has 334.3×104 m3 of solid material,of which about 156.8×104 m is prone to debris flow in the future when it encounters great rainstorms.The development trends of the debris flow in Xiaogangjian gully are as follows: 1) its strength of activity will keep reducing with the decrease of loose granular materials and total amounts of debris flow;2) the debris-flow's activity is transport-limited system right after the earthquake,followed by the transitional type between transport-limited system and weathering-limited system and ultimately is weathering-limited system.
引文
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[2]Cui P,Chen X Q,Zhu Y Y,et al.The Wenchuan Earthquake(12May 2008),Sichuan Province,China,and Resulting Geohazards[J].Nature Hazards,2011,56:19-36
[3]Chen Xiaoqing,Li Zhiguang,Cui Peng et al.Estimation of soil ero-sion caused by the 5.12 Wenchuan earthquake[J].Journal ofMountain Science,2009,27(1):122-127[陈晓清,李智广,崔鹏,等.5.12汶川地震重灾区水土流失初步估算[J].山地学报,2009,27(1):122-127]
[4]Tang Chuan,Liang Jingtao.Characteristics of debris flows in Bei-chuan epicenter of the Wenchuan Earthquake triggered by rainstormon September 24,2008[J].Journal of Engineering Geology,2008,16(6):751-758[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]
[5]Tang Chuan,Tie Yongbo.Reconnaissance and analysis on rainstorminduced debris flow in Weijiagou vally of Beichuan city after theWenchuan earthquake[J].Journal of Mountain Science,2009,27(5):625-630[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]
[6]Hu Kaiheng,Ge Yonggang,Cui Peng,et al.Preliminary analysis ofextra-large-scale debris flow disaster in Zhouqu county of Gansu prov-ince[J].Journal of Mountain Science,2010,28(5):628-634[胡凯衡,葛永刚,崔鹏,等.对甘肃舟曲特大泥石流灾害的初步认识[J].山地学报,2010,28(5):628-634]
[7]Su Pengcheng,Wei Fangqiang,Feng Hanzhong,et al.Causes andeffects of group-occurring debris flow disasters in Qingping town,Mi-anyuan river upstream,Sichuan[J].Journal of Mountain Science,2011,29(3):337-347[苏鹏程,韦方强,冯汉中,等.“8.13”四川清平群发性泥石流灾害成因及其影响[J].山地学报,2011,29(3):337-347]
[8]Tang Chuan,Li Weile,Ding Jun,et al.Field investigation and re-search on giant debris flow on Augest 14,2010 in Yingxiu town,epi-center of Wenchuan Earthquake[J].Earth Science-Journal of Chi-na University of Geosciences,2011,36(1):172-180[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——中国地质大学学报,2011,36(1):172-180]
[9]Li Chaoan,Hu Xiewen,Li Guanqi.et al.Formation mechanism ofthe'8.13'catastrophic debris flow in Sichuan and the principles ofcontrolling[J].Research of Soil and Water Conservation,2012,19(2):257-263[李朝安,胡卸文,李冠奇,等.四川省“8.13”特大泥石流灾害成生机理与防治原则[J].水土保持研究,2012,19(2):257-263]
[10]You Yong,Chen Xiaoqing(Eds.).Feasibility study report of Xi-aogangjian debris-flow mitigationin in Mianzhu County[R].Cheng-du:Institute of Mountain Hazards and Enviroment,CAS,2011.游勇,陈晓清主编.绵茂路汉清段小岗剑泥石流应急治理工程可行性研究报告[R].成都:中国科学院水利部成都山地灾害与环境研究所,2011
[11]Chen Xiaoqing,Cui Peng,Feng Zili,et al.Artificial rainfall experi-mental study on landslide translation to debris flow.Chinese Journalof Rock Mechanics and Engeering,2006,25(1):106-116[陈晓清,崔鹏,冯自立,等.滑坡转化泥石流起动的人工降雨试验研究[J].岩石力学与工程学报,2006,25(1):106-116]
[12]Cui Peng,Zhuang Jianqi,Chen Xingchang,et al.Characteristics andcountermeasures of debris flow in Wenchuan area after the earth-quake[J].Journal of Sichuan University:Engineering Science Edi-tion,2010,42(5):10-19[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]
[13]Bovis M J,Jakob M.The role of debris flow conditions in predictingdebris flow activity[J].Earth Surface Processes and Landforms,1999,24:1039-1054
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