
TY  - JOUR
A1  - Soma, N. 
A1  - Utagawa, M. 
A1  - Seto, M. 
A1  - Asanuma, H. 
T1  - Application of the tri-axial drill-bit VSP method to drilling for geological survey in civil engineering
JF  - Exploration Geophysics
JO  - Explor. Geophys.
Y1  - 2004
VL  - 35
IS  - 1
SP  - 70
EP  - 79
KW  - 
UR  - https://doi.org/10.1071/EG04070 
N2  - We have examined the applicability of the triaxial drill-bit VSP method (TAD-VSP) to the geological survey of possible sites for a high-level radioactive waste disposal repository. The seismic energy generated by a drill bit is measured by a downhole multi-component detector, and the resulting signals are processed to image the geological structure deep underground. In order to apply the TAD-VSP method to civil-engineering-scale drilling, we have developed a small but highly sensitive and precise three-component downhole seismic measurement system, and recorded drill-bit signals at a granite quarry. We have successfully imaged discontinuities in the granite, possibly related to fractures, as highly reflective zones. The discontinuities imaged by the TAD-VSP method correlate well with the results of other borehole observations. In conclusion, the TAD-VSP method is usable in geological investigations for civil engineering because the equipment is compact and it is simple to acquire the drill-bit signal. 
ER  -

