西南某水电站坝区岩体绿泥石化蚀变及其工程对策

西南某水电站坝区地质史上构造-热液活动复杂,岩体绿泥石化程度较高。经调查研究表明,坝区岩体绿泥石化蚀变既有热液成因,又有构造动力成因,其分布受岩性、构造、应力集中和浅表风化作用影响,在辉绿岩脉中蚀变强度最高,花岗岩中蚀变最强处往往远离断层分布,整体上由地表及深部,蚀变变弱。受蚀变影响,岩体总体性状变差,表现为变形模量偏低,结构面性状恶化。文章初步讨论了绿泥石化蚀变可能引起的主要工程地质问题及其工程对策。

Chloritized alteration rock mass and the engineering countermeasures in a hydropower station dam site in Southwest China

The tectonic-hydrothermal activity is complex in the geologic history,and the grade of rock mass chloritized alteration is comparatively higher at a hydropower station dam site in Southwest China.The study revealed that the chloritized alteration is caused by both the hydrothermal activity and tectonic dynamic,and its distribution is controlled by lithology,tectonics,stress concentration and weathering.Therefore the chloritized alteration of dolerite-dyke is the highest intensity.But in granite,the highest intensity is often far from the faults.As a whole,with the embedding' shoaling,the rock mass chloritized alteration is more and more stronger.Affected by alteration,the whole properties of the rock mass become worse,such as the low deformation modulus and the deterioration of the structure surface's properties.This article preliminarily discusses on the main engineering geological problems caused by rock mass chloritized alteration and correlated engineering countermeasures.