Directional core drilling in tunnel construction
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Transcript of Directional core drilling in tunnel construction
Directional core drilling in tunnel
construction
Directional core drilling
• Devico AS• Borehole survey systems• Directional core drilling
• DeviDrill directional core barrel• First version in 1988• Present version in 2001
• Projects• Geotechnical exploration• Mineral exploration
Geotechnical exploration
• Change direction of boreholes• Steer towards targets or keep hole within limits• Retrive core from the most relevant areas
Coring along planned tunnel alignment
• Continuous rock core• Fault zones• Fractures• Geological anomalies• Rock mechanical properties
• Hole for various analysis• Geophysical• Water in-/outflow• Hydraulic fracturing
Directional coring in Hong Kong
• 4 projects completed last five years• Traffic tunnels (2)• Drainage tunnels (4)• Sewage tunnels (6)
• Guidance note from the HK Government• “4.1 Directional drilling techniques are now available to drill from
ground level to great depth and then along a horizontal alignment. This method does not require provision of working space at the tunnel level and can be very useful in GI for deep tunnels.”
Eagle’s Nest
• 2 boreholes• 580 and 1150 meters• 8 m radius tolerance• Borehole between twin
tunnels• Fault zones
Pressure grouting schedules
Harbor Treatment Scheme, Stage II
• 6 boreholes• 600 to 1250 meters• 10 x 10m tolerance• Start inclination from -33° to -45°
Conclusion
• Accurate impression of the rock formations along the tunnel alignment
• Security during construction• Stabilization measures• Predict leakage and ground setting• Material estimations• Time & cost estimations
• Achieves reliable results, proven in mining and geotechnical exploration projects worldwide
Thank you for your attention!
www.devico.com