汶川强震区“8·20”登溪沟泥石流发育特征与致灾机理研究

Study on the Development Characteristics and Disaster Mechanism of Dengxi Gully Debris Flow in Wenchuan Meizoseismal Area on August 20,2019

登溪沟是汶川强震区“8·20”泥石流事件中典型的由暴雨诱发的大型灾害性泥石流,其泥石流持续时间达3 h,堆积长度达3.4 km,受沟道地形的放大效应影响,峰值流量达407.54 m^(3)/s。形成四个典型的灾难链。给沟口建筑、居民、公路及岷江上下游都带来了严重影响。地震为登溪沟泥石流提供了充足的物源,当持续性强降雨超过了研究区的阈值之后,泥石流就会起动,在运动过程中不断带走沿途沟道内的固体物质,最终发展为灾害性泥石流。笔者在现场充分调查的基础上,结合遥感卫星影像,从地震、降雨、物源和沟道侵蚀等方面揭示了登溪沟泥石流的形成和发展过程,并提出“以拦固为主,排导为辅”的治理思路,可作为强震区泥石流防治工程的参考。

Dengxi gully debris flow is a typical large-scale disastrous debris flow induced by rainstorm on August 20,2019 in Wenchuan meizoseismal area.The duration of debris flow is about 3 hours and the deposit length are 3.4 km.Affected by the gully topography,the peak discharge was amplificated to 407.54 m^(3)/s.Four typical disaster chains are formed in the gully,and it has brought a serious impact on the architecture,residents,roads and the upper and lower reaches of Minjiang River.But the earthquake also provides sufficient material source for Dengxi gully debris flow.When the continuous rainfall exceeds the threshold value of the study area,the debris flow will start and take away the solid material in the gully along the way in the process of movement,and finally develops into a disastrous debris flow.Based on site investigation and remote sensing satellite images,the paper reveals the formation and development process of Dengxi gully debris flow from the aspects of earthquake,rainfall,material source,gully erosion,and puts forward the treatment idea of relying mainly on retaining while drainage subsidiary,which can be used as reference for debris flow control engineering in meizoseismal area.