Geophysics Applied in Tunnel Pilot Boreholes for Pre-Grouting Design Parameters

A045 GEOPHYSICS APPLIED IN TUNNEL PILOT BOREHOLES FOR PRE-GROUTING DESIGN PARAMETERS Abstract 1 Geophysical logging was used in two pilot boreholes of an access tunnel to underground nuclear waste storage to provide design information for pre-grouting and support. Boreholes were diamond drilled from ground surface and tunnel. The surveys in first borehole were used to design the works and the advised methods were applied in the second pilot borehole drilled during tunnel excavation within a period of three days after which the excavation continued immediately and was interrupted over minimal time period. Logging methods were optical imaging flow logging borehole