【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。更多还原

【Abstract】 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.更多还原