Challenges in execution of concrete Face Rock-Fill dams in emerging economies

It is strongly believed that Concrete Face Rockfill Dams are proposed when the bed rock is not available-at reasonable depth for placement of concrete dam. However, this is not the actual case. CFRDs offer-economic solutions for suitable dams for power generation, irrigation or water supply in cases where there-is a dearth of natural construction material either for concrete aggregates or for impervious core. Placement-of CFRDs across rivers with thick RBM is definitely an added advantage particularly in Himalayas.

In India the first CFRD was constructed as a part of Dhauliganga Stage I hydroelectric power project in Uttarakhand, India. This 56m high dam was completed with a plinth on river deposits of 70m thickness-and on bedrock on the banks.

DMR has carried out design and engineering for 60m high CFRD for 1200 MW Teesta III hydroelectric-power project in Sikkim, India. In this case an innovative layout for spillway on both the banks and spillway-tunnel on right bank were proposed.

Small dams have been developed for irrigation purpose in Nepal and Cambodia. The Dhap dam in Nepal-has been completed with central spillway as bed rock of gneiss was available at a shallow depth. In case-of Stung Tasal CFRD in Cambodia the 21m high dam also comprised central spillway as the sound rock-was available at shallow depth below the weathered granite. At this project suitable impervious core material was not available for the earthen dam earlier contemplated. The paper discusses the advantages as well as challenges posed by CFRDs as a viable solution.