Experimental Investigation On Tamped And Cavity Decoupled Explosion In Rock-soil By Mili-explosive Charge

The seismic signal from an underground explosion can be greatly reduced if the explosive is detonated inside a large cavity rather than being tightly packed into surrounding earth materials. The method is referred to "cavity decoupling", which is very effective for concealing the underground nuclear explosion. Since 1959, the cavity decoupling explosion technique has been researched very deeply in abroad.Laws of propagation and attenuation of spherical stress wave in the geologic media have been studied in detail by means of mini-chemical explosion test in laboratory in this paper. The lows are fundamental to improve and develop theoretic models for underground explosions (tamped and cavity decoupled) on the stress wave propagation, safety and containment during the explosion. The mini-chemical cavity decoupling explosion test can be used to reveal various physical phenomena and the laws of the cavity-decoupling explosion, and to accumulate important information for verifying the seismic technology.Experimental techniques for simulating cavity decoupling explosion in laboratory wear developed, which include a center initiating explosive charge designed in shape of mini-spherical with yield equivalent to 0.125~8.00gTNT, circular electromagnetic particle velocity gages and aluminum bar strain gages measurement techniques, spherical divergent stress waves generator. Large amount of tamped and cavity explosion experiments had been made in granite, soil, cement mortar and water media environment, respectively. The results indicate that, mini-chemical explosion test in laboratory can be used to simulate the stress wave propagation of the underground explosion. The effect of cavity decoupling in rocks is clear, and the scaled cavity radius of full decoupled is about 40 m/kt1/3. The full decoupling factors (effective yield ratio of tamped-to-cavity explosion) according to different criteria are within 20-150. The explosion energy coupling in the soil is one order less than that in the rock. But the decoupling in soil is not clear. Coupling in water is very strong. If the cavity is full of water, the coupling effect will increase rather than reduce.