High Pressure Grouting of the Bath County Tunnel Systemby Walter J. Bogdovitz, Harza Engineering Co, Chicago, IL, USA,
Norman B. Holst, Harza Engineering Co, Chicago, IL, USA,
Abstract: A major grouting program was completed at the Bath County Pumped Storage Project between March and September 1985. High pressure grouting for seepage reduction was completed in a total of over 11,000 ft (3350 m) of conduit along sections of all three power conduits. Grouting pressures were raised from early to later sequence holes reaching a maximum final pressure of 600 psi (4140 kPa), commensurate with the conduit operating head of 1082 to 1262 ft (330 to 385 m). Although successful, the high grouting pressures caused difficulty with long distance grout travel, leakage, and communication. The problems were effectively controlled, however, by adjusting grouting methods and mixes. During the grouting program, stressmeters, water pressure tests, and geophysical surveys were used to evaluate the grouting effectiveness. This testing and the early operating history following the grouting indicate that the program was largely successful in achieving its objectives: reduced rock formation permeability, increased rock modulus of deformation, and added pre-stress in the concrete lining.
Subject Headings: Grouting | Conduits | Water pressure | Hydro power | Rocks | Permeability (material) | Tunnels | Water supply
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