Study of Water Tightness and Vertical Drainage Hole of Roller Compacted Concrete on Nam Ngiep 1 Hydropower Project in Laos

Abstract

A variety of resources have being applied to Roller Compacted Concrete (RCC) dams in the world, in order to secure the water tightness of the dam body. Treatment of concrete block joints, upstream portion and concrete placing joint as well as design of concrete mix proportion are important factors for the above purpose. In addition, usually vertical drainage holes are arranged in the dam body to drain the leakage water properly for reducing uplift pressure acting on concrete placing joints. The practice of the works for enhancing water tightness of the dam body in the Nam Nigep Hydropower Project in Lao PDR, which has a 167 m RCC dam, is introduced and its effectiveness is discussed through 2 dimensional finite element permeability analysis and proved through in-situ permeability test and observation of concrete placing joint by CT scanning.