风化作用对沟谷型泥石流发育环境的影响研究

Impacts of Weathering on Formation of Gullied Debris Flow

地质条件是泥石流发育环境的三大条件之一,其主要作用是为泥石流提供固体物源。风化作用对产生泥石流固体物源的影响很大。以岩石的坚固系数为基础,研究了物理及化学风化对形成泥石流固体物源的影响。研究结果表明:(1)物理风化是形成泥石流物源的主要原因,冰劈作用往往造成强烈的物理风化,有利于泥石流的发育;(2)化学风化不直接提供固体物源,但碳酸根离子的存在使化学风化不利于泥石流的发育。研究得出岩石坚固系数的物理风化和化学风化修正方法,最终得到形成泥石流的地质因子。形成泥石流的地质因子在汶川地震影响区内判别泥石流的暴发与否的应用研究中取得了较好的结果。

Geological condition, one of three debris forming factors, mainly provides the solid source for deb- ris flow, and weathering plays very important role in the formation of solid source. The article analyzed the influence of physical and chemical weathering on the formation of solid source based on the rock firmness co- efficient and concluded that： （1） The physical weathering, often caused by frost wedging in favor of the for- mation of debris flow, is the main reason for the development of the solid source of debris flow; （2） The chemical weathering does not provide the solid source directly while the carbanion is not in favor of the for- mation of debris flow. Based on the modification of the rock firmness coefficients by physical and chemical weathering, the geological factor forming debris flow is obtained, which was tested with good result in the judgment of debris flow outbreak in Wenchuan Earthquake area.