CONSTRUCTION OF CUT-OFF WALL BY LOW-HEADROOM-CUTTER INSIDE DAM TUNNEL IN CHINA

摘要

In the South of Sichuan province a 240 MW Yeleh hydroelectric plant was constructedby Sichuan Nanya River Basin Hydraulic Power Development Company Limited, a stateownedenterprise, and China Gezhou Ba Water & Power Group Company Limited. Thisproject sets out to develop the mountain cascade of the Nanya River, a tributary of theDadu River, provide superior electricity and adjust flood peak & frequency. Thespecialist contractor Foundation Engineering Company of China Water Resource andHydropower (FEC) was awarded the contract for foundation treatment at the right bank,which included the construction of a 75m deep concrete Cut-Off Wall (COW) inside a6.0m x 6.5m tunnel. The requirement for 19,317m~2 COW to be constructed in permeableand very dense gravel/cobble formations and a demanding project program led FEC toadopt Bauer Low Headroom Cutter CBC25/MBC30 in conjunction with Overlap CutterJoint (OCJ).