MINED ROCK TUNNEL THROUGH DAM ABUTMENT AT WARM SPRINGS DAM, SONOMA COUNTY, CA

摘要

HNTB-Gerwick JV was contracted by the United States Army Corps of Engineers (USACE) to perform 65% design for a tunnel alternative to replace an emergency water supply line (EWSL) at Warm Springs Dam, Sonoma County, CA. The tunnel alternative consists of a 72 inch diameter pipe in carrier tunnel, 4.0 m (13.0 ft) wide by 3.4 m (11.0 ft) high. The proposed tunnel consists of 610 m (2,000 ft) of mined tunnel and 107 m (350 ft) of cut and cover tunnel. The mined tunnel would be constructed through the left abutment of the dam in sandstone and shale under high head of water. Key design and constructability issues include seismic design considerations, mined tunneling in weak rocks, groundwater control and dam safety.