Development and analysis of computational model of geomechanical system “layered massif – working support”

Abstract

Purpose. Substantiating the method for forecasting rock pressure manifestation in the system "layered massifworking support" on the basis of displacement patterns detection at any arbitrary point of the preparatory working circuit during the computational experiments. Methods.Computational experiments were carried out on the basis of the finite element method using the solid computational domain, provided superlimiting non-linear behavior of the simulated materials. The use of numerical grid methods allows creating geometrically and physically complex simulation models and manipulate their state within a wide range.Findings. The calculations defined that with weak links between adjacent strata, acting shear stresses destroy them in the vicinity of working, and the contiguous rock strata deform with mutual sliding. Analysis of reduced stress area allows to substantiate with accuracy sufficient for mining computations a unified average structure of the computational domain that most comprehensively reflects all the main features of a real mining massif which are likely to influence computational error. This choice ensures the introduced error value within 10% in the entire range of mechanical parameters change of the rock massif strata.Originality. Stress-strain state of frame support and patterns of its change with increasing mining depth are nonlinear, especially with nearby rock strata entering the superlimiting state; formation of the plastic hinges system along the frame support circuit, which causes the development of such replacements that exclude the possibility of further working exploitation.Practical implications. The proposed method allows to determine the optimal indicators of maintaining a working driven in the finely-layered rock massif, which makes it possible to significantly reduce operation costs.

Thermal Impact on Heavy Metal Bioavailability in Burnt Rocks of Waste Heap of Chervonohradska Coal-preparation Plant (Lviv Region, Ukraine)

“…The planned investigation of variations in the bioavailable forms of heavy metals in argillites separately from argillites that have been affected by thermal effects will provide deeper insight into the processes of the geochemical transformations of such rocks and extend the results to other coal-mining dumps by making appropriate recalculations based on the ratios between the main dump rocks. The exploration of changes in heavy metal contents and bioavailability before and after rock combustion will create a scientific basis for utilizing waste heap rocks, recultivating disturbed areas [21][22][23], and optimizing coal mining and coal preparation [24][25][26][27].…”