Pre-Excavation Grouting at the Hemphill Site-Atlanta WSP Tunnel, Atlanta, Georgia

摘要

The City of Atlanta's Water Supply Program Tunnel Project, comprises a 24,000-ft long, 13-ft diameter, hard rock tunnel. A complex aspect of the project involves connecting five blind bore shafts to the tunnel in a location close to current drinking water reservoirs. During the supplemental geotechnical investigation following initial contract award, results from additional borehole geophysics were reviewed. Unfavorably oriented fracture sets forced a change in the original pre-excavation grouting program designed for that site. Real-time grout monitoring and geophysical data were compared to provide assurance that the program as designed correlates with the in-situ ground conditions. Following grouting, results were modeled, and all grouting data was reviewed to determine if grouting was complete.