EVOLUTION OF CRACKS AT THE EDGE OF A GAS-BEARING COAL SEAM IN ITS STATIONARY DEVELOPMENT
E. P. Fel'dman, N. A. Kalugina, O. V. Chesnokova
Institute of Physics of Mining Processes of the National Academy of Sciences of Ukraine, Dnepr, Ukraine
Keywords: газ, давление, трещина, фильтрация, разрыв, пласт, стационарная разгрузка, gas, pressure, fracture, filtration, fracture, formation, stationary unloading
Abstract
In this paper, we consider conditions under which the gas enclosed in the main crack located at the edge of a coal or rock formation can produce fracture of the formation. Kinetic theory is developed for two competing physical processes: formation unloading due to rock pressure and gas filtration from the crack cavity into the surrounding massif. The first process promotes fracture, and the second leads to a decrease in the gas pressure causing he fracture. The evolution of the crack is determined by the ratio of the rates of these processes. It is found that a modified Griffiths criterion is a necessary but not sufficient condition for fracture. For formation fracture, it is also necessary that the unloading rate to the filtration rate exceed a certain threshold value.
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