Perm Journal of Petroleum and Mining Engineering (Mar 2016)
Geomechanical justification of the application of concave-flat shape of mine excavation stope face to control sudden rock spelling
Abstract
In the conditions of Verkhnekamsk and Starobinsk potash deposits the phenomena of gas dynamics that represent sudden stope face rock spelling occur during primary and cleaning mining operations. Sudden spelling of stope face rocks starts from the flat face with rate of less than several tones. Nevertheless, its action threatens miners’ lives and leads to destruction of particular construction elements of valuable excavation and load-haul machinery. At the moment equipping of excavation and load-haul machinery by fence shields cannot protect staff from damaging factors of gas phenomena this kind. The paper shows results of geomechanical justification of application of concave-flat shape of mine stope face for control of sudden face rock spelling during excavation of primary and cleaning shafts. Space modeling of strain-stress state of salt deposits near the stope face of mine excavation was performed on boundary elements method in linear-elastic mode. To solve the problem of strain-stress state of piecewise-homogenous elastic medium by indirect method of boundary elements iteration scheme for border and dual elements was used based on Seidel method. Method included piecewise-linear approximation on triangle elements. During the operating of geomechanical model of linear-deformation medium solution superposition method was used. Wherein, calculation scheme consist of two parts: calculation scheme of virgin rock medium that is loaded by volumetric forces of overburden pressure and calculation scheme for weightless medium with mining with contour that is loaded by volumetric forces of overburden pressure that occur in virgin rock medium and directed towards mining. During the analysis of out-of-limit state of rocks near the stope face integrated criteria of Coulomb was used. Geomechanical evaluation was done for two shapes of faces: concave-flat and flat. It was determined that concave-flat shape of face in comparison with flat one has more stable state of salt rock medium ahead of stope face due to significant decrease of level of stress and deformation massif.
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