Abstract:

Inactive and regional fault has developed at the dam site of a hydropower station planned to be built in a gorge area. The fault, passing through the dam foundation at river bankside, can be divided into cataclasite zones and weak tectonic rock zones, of which the cataclasite zone width is about 86m to 92m and the weak tectonic rock zone width is less than 2.1m within the dam foundation. To provide geological data for the hydropower project design, one of the major tasks of engineering investigation is to ascertain the engineering characteristics of cataclasite rockmass, which includes distribution and scales, mineral components, physico-mechanical properties, and engineering properties. Furthermore, the corresponding treatment measures are presented. The research results indicate that slightly weathered and fresh cataclasite rockmass could be used for the foundation of concrete gravity dam whose maximum height is over 200m. It could meet the requirements of dam construction after full-area strengthening and consolidation grouting to depth 15m to 30m under the constructive foundation surface within the dam foundation. The research could provide reference for similar faults and cataclasites of other projects.

Key words: cataclasite, engineering property, treatment measure, dam foundation, hydropower station