# Studies of the Stress State of the Coal Pillar between the Treatment and Preparatory Workings by the Methods of Deformable Body Mechanics

Annotation:

To ensure safe conditions for mining operations and increase labor productivity, a reliable assessment of the stress state of the coal-rock mass is required. The model is presented concerning the geomechanical state of the massif hosting the coal seam, treatment, and preparatory workings. The model is developed based on the fundamental methods of solid mechanics and ensures a computational experiment and the reliability of the results.
Stress distribution in the coal-rock mass in the vicinity of the in-seam workings was calculated in two stages. First, the stress field in the edge zones of the coal seam and in the collapsed rocks was determined by the methods of mechanics of the flowing medium. Distribution of stresses in the extremely stressed zones of the seam and the layer of collapsed rocks behind the working excavation was found by the method of characteristics by solving differential equations of the hyperbolic type. They are obtained based on the of the joint solution of the equilibrium equations, general and special Coulomb — Mohr criteria of the transition of the seam and the collapsed layer, as well as their contacts with the lateral rocks to the limiting state. Then, by replacing  extremely stressed zones of the coal seam and the layer of the collapsed rocks with stresses acting at the contacts with the surrounding massif, the problem is reduced to the integral equation of the second external boundary value problem of the theory of elasticity. It is solved by the method of boundary integral equations.
Insignificant influence of changes in the angle of internal friction of the collapsed rocks on the parameters of the seam bearing pressure in the vicinity of the treatment and development workings is shown. However, it significantly effects on the bearing pressure in the extremely stressed zone of the collapsed rocks layer.

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DOI: 10.24000/0409-2961-2020-12-26-31
Year: 2020
Issue num: December
Keywords : rock mass coal seam mine working stress condition extreme stressed zones resistance characteristics coal pillars boundary problem of elasticity theory deformable body mechanics
Authors:
• Cherdantsev N.V.
Dr. Sci. (Eng.), Chief Research Associate, nvch2014@yandex.ru, Federal Research Centre of Coal and Coal Chemistry of SO RAN, Kemerovo, Russian Federation