Case study on engineering behaviors of the Simajiri mudstone for dam construction - slope reinforcement in dam reservoir

摘要

"K"dam was constructed with large excavation of Shimajiri group mudstone (Shimajiri mud-stone) deposited in Tertiary. This mudstone is low in strength (soft rock), weak consolidation and especially poor in slaking-durability, consequently it is easy to deteriorate and become muddy. The design and performance considering the characteristics of the mudstone were carefully studied for the dam construction and cut-slope in the dam reservoir. In this study, the rebound phenomenon accompanying with the excavation was observed by highly precise extensometer in the dam reservoir bed, and was related to the decrease of strength of the Shimajiri mudstone by laboratory tests. On the contrary, the decrease of strength was not observed in the cut slope countermeasured by concrete frame with a tie-back. These results indicate that this reinforcement method is highly effective to deterioration of Shimajiri mudstone and may be better consideration to solve the problems of the similar works in Shimajiri mudstone.