INCIPIENT FRACTURE OF COAL UNDER ONE DIMENSIONAL GAS SEEPAGE

The fracture of coal under one dimensional gas seepage is investigated. The experiments show that the incipient fracture of coal takes the shape of a spherical crown; the critical gas overpressure is dependent on the unloading condition, the strength, radius, confining pressure, length of the sample, and independent of the characteristics of gas adsorption. Numerical analysis demonstrates that the fracture belongs to tensile mode; the increase of unloading rate, decrease of confining pressure and increase o...