强震区泥石流防治工程效果数值模拟分析

[目的]对汶川地震后修建的大量泥石流防治工程的效果进行数值模拟分析,以便为泥石流研究和防治提供科学借鉴。[方法]采用FLO-2D软件,以2010年都江堰市龙池镇黄央沟"8·13"泥石流为典型实例,结合雨量数据、数字地形数据及泥石流的各项流变参数,模拟在不同的降雨频率下泥石流的运动过程和堆积范围,对泥石流的防治工程效果进行分析评价。[结果]在有防治工程条件下,当降雨频率P=5%时,泥石流的冲出量减小11.39倍,堆积范围减小6.14倍;当降雨频率P=2%时,泥石流的冲出量减小4.18倍,堆积范围减小2.7倍,治理工程取得了一定的防治效果,但两种降雨频率下仍有固体物质冲出沟口。[结论]相比于自然条件泥石流的冲出量和冲出规模得到了一定的控制,已有的治理工程有利于整个沟域泥石流的防治,但存在设计库容偏小的问题,今后的泥石流防治中还要加强监测预警等减灾措施。

Numerical Simulation and Analysis of Debris Flow Prevention Engineering Effects in Strong Earthquake Area

[Objective] After the Wenchuan earthquake, a large number of debris flow prevention engineering were constructed. The numerical simulation of the effects of debris flow prevention engineering in strong earthquake areas was analyzed to provide a scientific reference for the study and prevention of debris flow.[Methods] Using FLO-2D software, this paper simulates the movement process and accumulation range of debris flow under different rainfall frequencies, and analyzes and evaluates the effects of debris flow in the prevention and control project, combining rainfall data, digital elevation model(DEM) and rheological parameters of debris flow, taking the "8·13" debris flow in Huangyang gully, Longchi Town, Dujiangyan City in 2010 as a typical example.[Results] Under the condition of prevention engineering, when the rainfall frequency P=5%, the discharge volume of debris flow decreased by 11.39 times and the accumulation range decreased by 6.14 times; when the rainfall frequency P=2%, the discharge volume of debris flow decreased by 4.18 times and the accumulation range was reduced by 2.7 times. The prevention engineering achieved certain control effects, but solid matter still rushed out of the ditch at the two rainfall frequencies.[Conclusion] Compared with the natural conditions, the volume and size of the rushing out of the debris flow significantly reduced. The prevention engineering is conducive to the prevention and control of the debris flow in the gully. However, there will have the possibility of solid matter rushing out of the ditch, due to the small capacity of the reservoir. Therefore, hazard mitigation measures such as monitoring and early warning systems need to be strengthened in the further governance of debris flows.