Maintenance of reusable mine workings during the augering mining of coal seams

Abstract

The augering mining of thin and very thin coal seams has been proposed for using the efficiency of this task, related to the stability of reusable mine workings. The interrelation has been established and optimized between the support loading parameters in the extraction working during the augering mining of thin and very thin coal seams with the stress-strain characteristics of the protective monolithic strip of variable rigidity. The strength properties of sand-cement stone for the erection of rigid and yieldable parts of the protective strip are studied. The regression equations are obtained, which allow to determine the rational force, deformation and geometric parameters of the “support – protective strip” system elements during the extraction workings maintenance.

A Generalized View of Longwall Emergency Stop Prevention (Ukraine)

“…In the case of certain positions of a stope along the extraction pillar, a convergence value along the line of the location of hydraulic props of a powered support within its middle share may reach the one being higher than the admissible value of their yielding. In this case, there can be a cutting of the roof rock along the face line, resulting in the emergency longwall shutdown by a rigid settlement of the powered support units, which makes it impossible for both the movement of support units and the shearer to advance (Figures 3 and 4) [26,27,32,34].…”

“…In the case o positions of a stope along the extraction pillar, a convergence value along the lin location of hydraulic props of a powered support within its middle share may r one being higher than the admissible value of their yielding. In this case, there cutting of the roof rock along the face line, resulting in the emergency longwall sh by a rigid settlement of the powered support units, which makes it impossible the movement of support units and the shearer to advance (Figures 3 and 4) [26,2 When the support yield load is lost or the load formed on the support is exce often happens due to longwall shutdown or intense lamination of weak roof rock occurs rigid settlement of the hydraulic props (Figure 4) [26,32,34]. This emergency situation is not only connected to considerable operating c time for the release of the compressed units but also to their failures (the colla canopies with props, swelling of hydraulic cylinders, and other deformations).…”

“…The direction of seam mining and the displacement of the support units, relative to the system of natural fissility of the roof rock, greatly influence the stable operation of a powered support in terms of prevention of the formation of a considerable length of rock hanging over a face. In this context, timely breaking requires When the support yield load is lost or the load formed on the support is exceeded (it often happens due to longwall shutdown or intense lamination of weak roof rocks), there occurs rigid settlement of the hydraulic props (Figure 4) [26,32,34]. This emergency situation is not only connected to considerable operating costs and time for the release of the compressed units but also to their failures (the collapsing of canopies with props, swelling of hydraulic cylinders, and other deformations).…”

“…Thus, the hanging length of the roof rock consoles does not increase considerably, and support pressure does not experience sharp changes. All the transitional processes in stress changes are smoother compared with the shearer-based extraction method [31,32]. This parameter can be applied in all cases in terms of either available or no available sandstones in the roof.…”

“…Bondarenko et al [31] presented substantiation of the parameters for preventing rigid settlement of a powered support while coal seam mining, in terms of MSS "ShU Ternivske" of "DTEK Parlohradvuhillia" PJSC. Bondarenko et al [32] showed the results of mine studies and computational experiments by a finite element method to calculate a stress-strain state of rock mass while mining thin and very thin coal seams under complicated mining and geological conditions in the Western Donbas mines. Scientists of the "Dnipro University of Technology" [33] indicated the zones of stoping effects on the interaction of powered support and roof rocks.…”