云南维西哈达沟中频泥石流特征及堵溃危险性分析

Characteristics of intermediate frequency debris flow and analysis of the hazard of blockage in Hada gully,Weixi County of Yunnan Province

中频泥石流具有较大危险性和暴发周期较长的特点,人类活动会诱发其发生并加剧其成灾严重程度,当沟道不能满足泄流输水能力时将发生堵溃,危及两岸甚至是主河河道安全。由于目前中频泥石流危险性分析的缺乏,因此以云南省哈达沟中频泥石流为例,探讨其特征和再次发生泥石流及导致沟道堵溃的危险性,并提出防治建议。结果显示:泥石流重度1.62 t/m^(3),泥石流沟口流速4.794 m/s,基于暴发频率10%情况下的沟口峰值流量为54.43 m^(3)/s以及一次冲出总量为11072.03 m^(3);在下游沟道处修建有涵洞,其过流量为16.5 m^(3)/s,小于20 a一遇泥石流流量,一旦发生大型泥石流,则有堵溃危险。研究发现哈达沟中频泥石流危险度为高度危险,堵溃历史判断其再次发生沟道堵溃并有泥石流堵塞腊普河的可能性。

Intermediate-frequency debris flows has the characteristics of high danger and long outbreak period.Human activities can trigger its occurrence and aggravate its disaster severity.When the channel cannot meet the capacity for drainage and water transport,it will cause blockage and endanger the safety of both sides of the strait and even the main river channel.Due to the lack of analysis on the danger of intermediate-frequency debris flows,this paper takes the intermediate-frequency debris flow in Hada Gully,Yunnan Province as an example to explore its characteristics and the danger of its recurrence and channel blockage caused by debris flows and proposes prevention and control suggestions.The results show that the debris flow has a density of 1.62 t/m^(3),a flow velocity of 4.794 m/s at the outlet of the channel,a peak flow rate of 54.43 m^(3)/s at the channel outlet and a total discharge of 11072.03 m^(3) for a single occurrence based on the 10%burst frequency.A culvert was constructed in the downstream channel,with a flow capacity of 16.5 m^(3)/s,which is less than the flow rate of a debris flow once in 20 years.Once a large debris flow occurs,there is a risk of blockage.The study found that the hazard level of intermediate-frequency debris flows in Hada gully is highly dangerous,and the history of blockage indicates the possibility of its recurrence and the risk of debris flow blocking the Lapu River.