Application of borehole radar to various rock masses in Japan; On the results of singlehole measurements

Semba, Tsuyoshi ; Ogata, Nobuhisa ; not registered

Power Reactor and Nuclear Fuel Development Corporation (PNC) has been developping techniques for evaluation of the spatial extent and dimension of fracture zones in rock mass. In a link of this purpose, PNC introduced the borehole radar system (RAMAC) which was developped in Stripa Project by OBCD/Nuclear Energy Agency. This report describes the results of singlehole measurements which were conducted in various rock masses in order to confirm the applicability of RAMAC system in Japan. The results are su㎜arized as follows; (1)For each borehole, we made radar reflection map, and interpreted reflectors from the map. (2)The propagation distance of electromagnetic waves through rock masses is determined by electric resistivity of rock masses. In the rock mass which resistivity is 100m, propagation distance is less than 5m from a borehole with 20 MHz antenna. In the rock mass which resistivity is 10,000m, propagation distance is at least 100m from a borehole with the same antenna.