丹巴县邛山沟特大灾害性泥石流汇流过程分析

在实际调查的基础上,对2003年7月11日发生在四川省丹巴县邛山沟的特大灾害型泥石流汇流过程进行了模拟.研究发现,邛山沟泥石流的产生,系由于流域基岩表面的残破积物在70多天的断续降雨过程中饱和或接近饱和,在7月11日晚突降暴雨的作用下,沿途坡面土体基本同时启动,坡面泥石流汇流,产生高容重的粘性泥石流,最后与左支沟(甲沟)的洪水汇合形成大规模的泥石流.沿途由于粗大颗粒的堵塞,峰值流量在有些断面迅速增大.

Conflux process analysis of desastrous debris flow in Qiongshan Ravine,Danba,Sichuan Province

Based on field survey and conflux simulation of the disastrous debris flow occurred in Qiongshan Ravine,Danba,Sichuan Province in July 11,2003,it is concluded that the loose soil in deposit is saturated after 70 days raining there. The loose soil began to move and came into being debris flow when rainstorm fell at the night of July 11. The debris flow grew bigger along the channel. There are three major factors to increase the debris flow discharge. Firstly, the deposit on bed is added. Secondly there are 16 slope debris flow sites that join the main stream at nearly the same time.Thirdly, in the main stream of Jia Valley the flood added into the moving debris flow.At the last, the big boulders block moved along with debris flow and made a peak discharge. As a result, the debris flow transformed into high density viscous one. The maximum velocity can be calculated to be 9.4 m/s, and the peak discharge reaches 4836 m~(3)/s with velocity 8.5m/s, the average depth of mud-line is 8.1m.