小江流域不同岩性风化物颗粒级配特征实验研究

Experimental Reaserch on Particle Distribution Characteristicsof Weathered Products with Different Properties in Xiaojiang River

摘要:

松散固体物质的颗粒级配决定着它的结构和连接特征，影响着其力学性质，是影响泥石流起动的决定因素之一。以中国泥石流极为发育的小江流域为研究区，采集流域上、中、下游5个流域、9种岩石类型的48个随高程变化的风化产物样品及5个典型泥石流沟的堆积样品，采用筛析和激光粒度分析相结合的方法对各样品进行颗粒分析。选择与泥石流起动、运动密切相关的d50，Cu,Cc及粘粒含量4个指标构建指标体系，系统分析了各类岩性对于各项指标的差异规律，结果表明，对于各项指标，各类岩性风化物均差异显著，且随指标不同，其级配特征差异规律显著不同; 5个典型流域泥石流堆积物在各项级配特征指标上均具有较好的一致性。d50,Cu,Cc及粘粒含量所构建的指标体系能较为客观、系统、合理的反应各风化产物的物理性质，可为基于风化物颗粒级配特征的泥石流对岩性的敏感性研究提供帮助。

Abstract:

As response characteristics to structures and interlinkages of weathered products with different properites，particle distribution influences the mechanical property of weathering products. It is one of the most important influence factor upon the initiation of debris flow. In this paper, taking Xiaojiang basin which debris flow developed well as the study area, collecting 48 samples weathering products which will change with different elevations in 9 kinds of rocks in 5 debris flow valleys in upper, middle and lower reaches of Xiaojiang ravine and 5 samples of debris flow deposition, particle distribution characteristic of each sample has been analyzed by using sieve analysis and laser particle size analysis method. Seclecting four indicators, such as d50,Cu,Cc and Clay content which have close relation with debris flow starting and moving, the index system has been constructed, and the difference laws of particle distribution characteristic upon each indicator has been systematically analyzed. It is indicated that as to each indicator, there are significant differences in weathering products in different rocks, and difference laws are significant different varying with different indicators . In addition, to each indicator ,there are good consistency lying in particle distribution characteristics of debris flow deposits of 5 debris flow valleys in Xiaojiang ravine. It also indicates that the index system ,which consists of d50,Cu,Cc and Clay content, can systematically, objectively and reasonably reflect the particle distribution characteristics of weathering products. It may be helpful for susceptibility analysis of debris flow to rocks based on particle distribution characteristics of their weathering products.