The concentration of methane gas which exists in the exhaust air from a coal mine is critical. It can be controlled by dilution of the gas with fresh air or by the regulation of the rate of methane emission into the mine workings. Degasification techniques which control the emission rate are currently being developed. The use of shaped charges to initiate fractures in coal and increase the gas flow rate was the object of this research. The three areas of investigation were: 1) permeability changes in coal models after fracturing with shaped charge jets, 2) fracture formation in coal and other brittle materials, and 3) jet penetration capabilities of charges loaded with permissible explosives. The first order penetration law, the Allison-Vitali equations, and their modification by DiPersio to account for continuous and broken jets have been used in attempts to predict jet penetration depth in metallic targets. Correction factors for the effects of material properties are used in these equations, but the specific properties which control the penetration rate were undefined and were investigated in this study. The results of this research indicate that the permeability of coal can be increased for degasification purposes by the use of shaped charge jets. The fracture formation which resulted from the jet penetration was studied with radiographs and highspeed photography and indicated that longitudinal wave velocity, Young\u27s modulus, and tensile strength are related to penetration depth --Abstract, page ii
