西藏林芝地区冰川降雨型泥石流起动实验初步研究

近年来,由于全球气温升高,导致西藏地区泥石流暴发频率增加,其中包括冰川降雨型泥石流灾害。以西藏林芝地区的冰川降雨型泥石流为研究对象,首次通过观测冰川降雨型泥石流起动过程中水位、孔隙水压力等变化特征,得到水位、孔隙水压力与堆积坡度、堆积厚度的关系以及沟道物质起动特征,根据水位、空隙水压力的时间变化特征,得到不同试验条件下水位与孔隙水压力的相互关系。通过相似物理实验,分析实验过程中流量、流深、流速等参数与泥石流堆积坡度、堆积厚度的关系,并将冰川降雨型泥石流起动分为前期饱和阶段、起动阶段、堆积阶段。由相似比得到研究区典型冰川泥石流起动的流深、流速等野外观测结果与实验结果与一致,为研究区冰川降雨型泥石流的研究提供参考。

PRELIMINARY STARTING EXPERIMENT STUDY OF GLACIAL- RAINFALL DEBRIS FLOW，IN NYINGCHI，TIBET

In recent years，with the global temperatures rising，the frequency of debris flow breakout events has increased，which includes glacial-rainfall type debris flow disasters in Tibet region. This paper will set the glacial- rainfall debris flow gully in Nyingchi of Tibet area as the research object，by observing the vary characteristics of water levels，pore water pressure in the starting process for the first time to get the relationship and its starting characteristics by water levels，pore water pressure，the slope，and the thickness of accumulation. By similar physical experiments，relationship of the experimental parameters among flow rate，flow depth，velocity and the slope，thickness of debris flow accumulation，the vary relationship of water level and pore water pressure are analyzed，according to the time relationship of the water level，pore water pressure under different test conditions，we could define the glacial-rainfall type debris flow starting process，which consists of early stage of saturated phase，starting phase and accumulation stage. The experimental results of flow depth，velocity are consistent with the field observation results of typical glacial debris flow in the study area，which are obtained by ratio of similitude provides the reference for the glacial-rainfall type debris flow study in research area.