四川康定姑咱“8·3”特大山洪泥石流发育特征及孕灾成因研究

Development Characteristics and Disaster-Causing Mechanisms of the“8·3”Catastrophic Flash Flood and Debris Flow in Guzan,Kangding,Sichuan Province

2024-08-03,四川省甘孜藏族自治州康定市姑咱镇日地村突发特大山洪泥石流灾害,导致雅康高速公路康定至泸定段日地1号隧道至2号隧道之间的桥梁垮塌,当地村庄房屋被冲毁,造成23人失联、4人遇难。结合无人机航拍和现场调查等技术手段,对日地沟泥石流的发育特征进行了详细分析,初步探讨了此次泥石流的发生过程和成因机理,并对其关键运动特征参数进行了计算,进而采用FLO-2D模型对日地沟泥石流的动力演化过程进行了模拟分析,模拟结果Ω验证精度达到1.65。研究结果表明,流域内固有的陡峻地形、风化碎裂花岗岩体提供的丰富物源以及持续性降雨与冰雪消融耦合的极端气候共同诱发了本次特大山洪泥石流灾害。本次山洪泥石流携带的固体物源约为58×10^(4)m^(3),其中最大孤石直径达6 m,流速超过8 m/s,单个块体的冲击力超过500 kN,流通区的总冲击力可达百吨以上,具有极大的破坏力。该研究成果有助于提升西南山区山洪泥石流的应急处置和防灾减灾工作。

Objectives:On August 3,2024,a catastrophic flash flood and debris flow devastated Ridi Vil⁃lage in Guzan Town,Kangding City,Sichuan Province.This disaster led to the collapse of a bridge on the Yakang Expressway between the Ridi No.1 and No.2 tunnels and destroyed several homes in the village,re⁃sulting in 23 people missing and 4 confirmed fatalities.Methods:To gather critical information and support emergency rescue operations,an in-depth analysis of the Ridi Gully debris flow was conducted using drone aerial photography and on-site investigations.The study examined the formation processes and underlying causes of the debris flow,with key dynamic parameters being calculated.These data were then used to simulate the dynamic evolution of debris flow using FLO-2D software,and the verification accuracy(Ω)of simulation results reached 1.65.Results:The findings suggested that the debris flow was primarily trig⁃gered by internal factors,including the steep terrain of the watershed,the presence of weathered and frac⁃tured granite,and the abundance of loose material within the gully.External factors such as recent temperature increases,which accelerated snow and ice melt,along with sustained rainfall,created the conditions necessary for the debris flow to occur.The flow transported approximately 58×10^(4)m^(3)of solid material,with the largest boulders measuring up to 6 m in diameter,while most ranged between 20 cm and 1 m.The flow velocity exceeded 8 m/s,and the impact force of individual boulders was over 500 kilonewtons,with the total impact force in the flow path surpassing 100 tons,resulting in significant destructive power.Con⁃clusions:Critical insights into the formation and mechanics of the Ridi Gully debris flow offer valuable gui⁃dance for emergency response and disaster mitigation in regions with similar geological hazards in the moun⁃tainous areas of southwestern China.