Influence of Spatial Orientation of Initiator-Notch on Roof Rock Deformation Near Production Face in Directional Hydraulic Fracturing
V. I. Klishin1, L. D. Pavlova2, V. N. Fryanov2, A. B. Tsvetkov2
1Federal Research Center for Coal and Coal Chemistry, Siberian Branch, Russian Academy of Sciences, Kemerovo, Russia
2Siberian State Industrial University, Novokuznetsk, Russia
Keywords: Coal seam, mine roadways, hard roof, modeling, stresses, deformations, residual strength, initiator-notch in hydraulic fracturing
Abstract
A boundary value problem is formulated for the stress-strain modeling of rock mass with regard to nonlinear deformation of rocks in the influence zones of mine roadways. Different variants of boring patterns for the directional hydrofracturing of hard roof, such that reduce the risk of geodynamic events in longwall mining of flat coal seams, are discussed. Numerical modeling shows that the most effective variant is arrangement of an initiator-notch in the seam roof in parallel to natural bedding in coal-rock mass. It is found that initiators-notches ensure a substantial decrease in roof rock displacements above production faces because of stress relaxation in rocks between induced fractures and coal seam. This effect grows when the length of an initiator-notch is increased to 10-20 m.
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