震后灾区泥石流阻塞大河判据与成灾模式试验研究
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摘要
震后汛期的实践表明,泥石流是震后最为活跃的灾种,泥石流堵河成为一种频繁的灾害事件。研究汶川地震灾区典型的泥石流堵河事件,并归纳出震后泥石流堵河的特点及其灾害链效应。针对岷江流域泥石流多半是以堰塞坝形式局部阻塞主河的现象,运用大型室内水槽试验再现交汇角为90°时高容重泥石流入汇主河的过程。试验结果表明:泥石流入汇主河的运动过程是后续泥石流逐步推移龙头运动的过程;泥石流总量对堵河有重要的影响,总量越大堵河越严重;在泥石流堵河过程中,主河的流速随堵塞系数R先增大后减小,当R小于0.8时,堰塞坝的物质流失量少,上游水位壅高值呈线性增加,当R大于0.8时,堰塞坝的物质流失量严重,上游水位壅高值呈指数增加。基于堵塞系数R对于预估泥石流堵河灾害的关键作用,以模型试验数据为依据,导出泥石流阻塞大河的判据。基于堰塞坝局部阻塞主河使水位壅高致灾的现象,给出水位壅高值计算式,为计算淹没范围提供依据。
Post-earthquake,in flood season mud-rock flow is one of the most active disaster species,disasters events of damming rivers by debris flow is increasing. This paper studies the typical events of damming river by debris flow after the Wenchuan earthquake. The features and disaster chain of the river-blocked by post-earthquake debris flow are proposed. In the Minjiang river,most of events are partially damming the main river as a barrier dam. Using flume experiments,reappearing of damming large river by debris flow with high density viscous debris flow and intersection angle is 90 degrees. The experimental results show that the thrust force of the follow-up debris flow is a main dynamic force driving the debris flow in the main river; Total volume of debris flows is an important effect on damming large river,which become seriously with the volume of debris flow increasing; In the process of debris flow damming river,when damming coefficient R increasing,velocity of main river firstly increases and then decreases,when R less than 0. 8,the lost material of debris flow is very little,head-water level is increasing linearly; When R more than or equal to 0. 8,the lost material of debris flow become seriously,head-water level is increasing exponentially. Based on the importance of the damming coefficient R for forecasting hazard and the model test data,the criteria of large river damming by debris flow are proposed. Depend on the disaster phenomenon caused by the raising of head-water level. The equation of calculate the value of head-water level is given,which propose a method for calculate the value of scopes of back up water level.
Post-earthquake,in flood season mud-rock flow is one of the most active disaster species,disasters events of damming rivers by debris flow is increasing. This paper studies the typical events of damming river by debris flow after the Wenchuan earthquake. The features and disaster chain of the river-blocked by post-earthquake debris flow are proposed. In the Minjiang river,most of events are partially damming the main river as a barrier dam. Using flume experiments,reappearing of damming large river by debris flow with high density viscous debris flow and intersection angle is 90 degrees. The experimental results show that the thrust force of the follow-up debris flow is a main dynamic force driving the debris flow in the main river; Total volume of debris flows is an important effect on damming large river,which become seriously with the volume of debris flow increasing; In the process of debris flow damming river,when damming coefficient R increasing,velocity of main river firstly increases and then decreases,when R less than 0. 8,the lost material of debris flow is very little,head-water level is increasing linearly; When R more than or equal to 0. 8,the lost material of debris flow become seriously,head-water level is increasing exponentially. Based on the importance of the damming coefficient R for forecasting hazard and the model test data,the criteria of large river damming by debris flow are proposed. Depend on the disaster phenomenon caused by the raising of head-water level. The equation of calculate the value of head-water level is given,which propose a method for calculate the value of scopes of back up water level.
引文
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[5]陈德明,王兆印,何耘.泥石流入汇对河流影响的实验研究[J].泥沙研究,2002(3):22-28(Chen Demeng,Wang Zhaoyin,He Yun.Experimental study on the effect of debris flow into the sink on the river[J].Study on Sediment,2002(3):22-28(in Chinese))
[6]陈德明.泥石流与主河水流交汇机理及其河床响应特征[D].北京:中国水利水电科研究院,2000
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[8]刘翠容,姚令侃.泥石流堵塞大河的特点及异岸受灾判据研究[J].四川大学学报:工程科学版,2012(5):93-100(Liu Cuirong,Yao Lingkan.Study on features of riverblocked by debris flow and criterion of disaster at the opposite river bank[J].Journal of Sichuan University:Engineering Science Edition,2012(5):93-100(in Chinese))
[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.Characteristics of debris flows in Beichuan epicenter of the Wenchuan Earthquake triggered by rainstorm on September 24,2008[J].Journal of Engineering Geology,2008,16(6):751-758(in Chinese))
[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(13):341-349(Tang Chuan.Activity tendency prediction of rain fall induced landslides and debris flows in the Wenchuan earthquake areas[J].Journal of Mountain Science,2010,28(13):341-349(in Chinese))
[4]郭志学,曹叔尤,刘兴年,等.泥石流堵江影响因素试验研究[J].水利学报,2004(11):39-45(Guo Zhixue,Cao Shuyou,Liu Xingnian,et al.Experimental study on parameters affecting theriver-blockingdue to debris flow[J].Journal of Hydraulic Engineering,2004(11):39-45(in Chinese))
[5]陈德明,王兆印,何耘.泥石流入汇对河流影响的实验研究[J].泥沙研究,2002(3):22-28(Chen Demeng,Wang Zhaoyin,He Yun.Experimental study on the effect of debris flow into the sink on the river[J].Study on Sediment,2002(3):22-28(in Chinese))
[6]陈德明.泥石流与主河水流交汇机理及其河床响应特征[D].北京:中国水利水电科研究院,2000
[7]肖焕雄.施工水力学[D].北京:水利电力出版社,1992:14-15
[8]刘翠容,姚令侃.泥石流堵塞大河的特点及异岸受灾判据研究[J].四川大学学报:工程科学版,2012(5):93-100(Liu Cuirong,Yao Lingkan.Study on features of riverblocked by debris flow and criterion of disaster at the opposite river bank[J].Journal of Sichuan University:Engineering Science Edition,2012(5):93-100(in Chinese))
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