Destruction of granite and concrete in water with pulse electric discharges

The possibilities of electropulse destruction of nonconductive materials and boring at various laboratory and field conditions have been studied at Tomsk Polytechnic University for many years. The test laboratory experiments in this work are realized under the following conditions: two electrodes are placed on the plate surface of a coupon. The coupon is immersed into a tank with insulation liquid. Pulse voltage is applied between electrodes. When pulse duration is less than 1 /spl mu/s and insulation liquid is used, the discharge channel occurs in solid material and causes its destruction. The usage of water as an insulation liquid did not show good results, because water has less breakdown voltage and provides considerable current leakage. This work is devoted to determining the possibilities of water use to demolish granite and concrete at large distance between the electrodes. It was found that the breakdown voltage during the pulse drop is 1.5-2.0 times less than that for the case when the discharge happens during the pulse rise. Consequently, we have less voltage amplitude and current leakage in water. The possibilities and the efficiency of the electropulse destruction of rock and concrete in water are discussed. The mechanism of discharge channel penetration in a solid is also discussed.