Preliminary Analysis of Mechanism and Phenomena of Deep Weathering in Some Hydroelectric Station,Southwest of China

Standing to phenomena of deeply weathering at the bottom of the dam area valley in some hydroelectric station,southwest of China,by the systematic geologic surveying,the data of borehole,the result of EH-4 e1ectrical conductivity image-forming system and indoor tests analysis,the deeply weathering phenomenon characteristics and its distribution are analyzed,and preliminary discussion on the genetic mechanism of the deeply weathering and softening is made.The results of study enunciate,there is ancient rock mass which is reformed by the intrusive activity many times at the bottom of the dam area valley,because of the weak cohesion bonds the dissimilar epoch contact plane of the rock mass become the compressive rupture zone,later tectonic movements make the rock mass of compressive rupture zone further broken up under medium confinement pressure,since middle Pleistocene epoch long-term weathering and yielding,current deep weathering bag has been formed.With the fitting processing,the phenomena of deeply weathering don't hinder the dam as the address of low rockfill dam.