公格尔山区融水冲刷形成泥石流的起动试验研究

Experimental study on scour by debris flow induced by snowmelt water conditions

近年来新疆公格尔山地区冰川泥石流活动频发,严重威胁中巴经济走廊带内重大工程的建设与运营。以公格尔山地区的冰雪融水型泥石流为研究对象,基于水槽试验,分析不同融水量冲刷冰碛土形成泥石流的起动机理。结果表明,在融水渗流侵蚀作用下,骨架结构的冰碛土内细颗粒不断迁出并形成渗流通道,随着内部结构变化和动水压力增加,前缘土体骨架发生坍塌形成小型泥石流;在后续持续水流冲刷作用下,处于超饱和的冰碛土不断溯源冲刷且表面形成小冲沟,在深切拉槽过程中局部沟段发生堵塞溃决而形成更大规模泥石流。综合含水量和孔压的变化特征及实验现象,将冰雪融水型泥石流的起动过程分为径流渗透、溯源冲刷、沿程冲刷和堵塞溃决等4个阶段。

Debris flow in the KongurMontain, induced by glacial-melt water, is studied on the basis of flume experiment. Processes of water content and pore water pressure are monitored, and the experimental phenomenon is surveyed by the videos. Results indicate that migration of fine sand particles inside moraine soil cause the formation of seepage channel by seepage erosion, and the change of internal structure and pore water pressure increase cause frame collapse in the front edge, and further a small debris flow is triggered. Under the effect of continuous water scouring, the super surface of saturation moraine soil is scraped into a gully by retrogressive erosion, and local channel blockage happens during downward scour and lateral erosion. A larger scale debris flow occurs next. The triggering processes of debris flows induced by glacial-melt water can be divided into four stages, as runoff infiltration, traceability erosion, scour starting and blockage outburst.