高位远程崩滑碎屑流-泥石流灾害链的演变过程与影响范围预测——以“4·5”四川洪雅县铁匠湾地质灾害链为例

Research on Evolution Process and Impact Range Prediction of High Level Remote Collapse and Landslide-Debris Flow Disaster Chain——Taking the “4·5” Tiejiangwan Geological Disaster Chain in Hongya County,Sichuan Province as an Example

20世纪以来,地质灾害以灾害链形式出现的频率明显加大,目前对灾害链的演变过程以及影响范围的研究并不多。本文以2021年4月5日四川洪雅县铁匠湾高位远程崩滑碎屑流-泥石流灾害链为例,阐述了灾害链的演变过程。启动源为高位崩塌,崩落的大量岩块对下方斜坡岩土体造成冲击和加载形成滑坡,受降雨影响,崩滑碎屑流物质向双溪河发展演变为泥石流;采用RAMMS软件对泥石流的运动过程进行数值模拟分析,划定了其在不同降雨频率下的影响范围。结果表明:在20 a一遇降雨频率下,影响范围涵盖了双溪村上游部分分散农户;在50 a一遇降雨频率下,影响范围覆盖双溪村人口密集区;在100 a一遇降雨频率下,影响范围将继续向下游发展,延伸至老赵河聚居区。灾害链发生期间,附近最大降雨量接近10 a一遇,将10 a一遇模拟结果与现场实际形成的影响范围进行对比,发现两者基本一致,说明模拟结果可信。

Since the 20th century,the frequency of geological disasters appearing in the form of disaster chains has significantly increased.Currently,there are few researches on the evolution process and impact scope of the disaster chain.In this paper,the evolution process of the disaster chain was illustrated taking the high-level remote landslide debris flow disaster chain in Tiejiangwan,Hongya County,Sichuan Province on April 5,2021 as an example.The initiation source is high-level collapse,and a large number of falling rock blocks impact and load the rock and soil mass on the lower slope to form a landslide,and then the avalanche debris flow material of the landslide develops into a debris flow towards the Shuangxi River under the influence of rainfall.RAMMS software was used to numerically simulate and analyze the movement process of the debris flow,and its impact range was delineated under different rainfall frequency.The results show that the impact scope covers some scattered farmers in the upstream of Shuangxi Village under the frequency of rainfall in 20 a,the impact area covers the densely populated area of Shuangxi Village under the frequency of 50 a,and the impact area will continue to develop downstream and extend to the residential area of Laozhaohe under the frequency of 100 a.During the disaster chain,the maximum rainfall in the vicinity of Tiejiangwan close to the frequency of 10 a rainfall.It was found that the simulated results of the 10 year return period was consistent with the actual impact range,indicating that the simulation results were reliable.