Results of analytical, laboratory and mine studies of parameters of disintegration zones in structurally-heterogeneous rocks and fracture systems around of the deep mine roadways are presented. A mathematical model is proposed, which is realized with the help of the procedures of simulation modeling by finite element method. Based on the calculation of possible directions of the rock shearing (the “rock shear sites”) and breakage of bonds between the elements, the model allows determining orientation of dominant master fracture system development with taking into account natural structural defects in the rock massif. A new algorithm was created for determining master cracks and boundaries of disintegration zones with the layered rock, which differs by determining directions of rock shear sites in the elastoplastic problem considering residual strength and main structural defects of the structurally-heterogeneous rock massif. Regularities of organization of unidirectional rock shear sites and their distribution under the influence of mining operations in zones with inelastic deformations were established.
Purpose. To reduce risk of emergency and injury-risk situations while improving the methods for predicting stressstrain state of the rock mass with the help of information systems, and to detect fissure locations in the mine roadways with the help of radiometric control.Methods. Analysis and generalization of experimental data; mathematical modeling of geomechanical and filtration processes by means of the finite element method; underground investigations of changes in activity of α-radiation of certain radon-isotope in the atmosphere of the mine roadways using standard methods as well as radiometric control equipment; and statistical processing of measurement results.Findings. Ratios, determining correlation between parameters of geomechanical process (i.e. fracture porosity, inclination angles of the fracture networks and their strike) and parameters of gas-dynamic process (i.e. intensity, gas flow rates and direction of gas travel) have been obtained. A mathematical model based on the finite element method is proposed in which a reasonable assumption is made that deformation of the pore medium is equal to the varied volume of the pore and fracture area. In the context of the model, deviation part of the strain tensor determines changes in the shape of the rock mass elements during disintegration. Spherical part of the strain tensor characterizes changes in volume and permeability of the pore and fracture area; it is determined by a value of minimum principal strains of the model elements. Parameters of the pore and fracture area location, volume and permeability were substantiated in the rock mass. The mine investigations have helped determine that within the areas of geological dislocations, concentration of radon daughter decay product of alpha-radiation polonium (Po 218 ) experiences more that 2 -4 times increase in relation to the roadway average value. On the basis of the criterion, it is proposed to use radiation monitoring of the mine roadways to identify areas of newly formed fracture systems resulting from fracture system deformation as one of the elements of method for the integrated control of the rock mass state. Originality. For the first time, regularities of changes in the pore and fracture area shape and volume at different stages of the adjacent longwall mining have been determined basing on parameters of technogenic fracture system orientation and spherical part of the strain tensor. The method of controlling the safe state of rocks has been further developed; it differs in the use of the determined ratios between changes in fracture system parameters and changes in α-radiation activity of some radon isotopes, methane concentrations and their correlation.Practical implications. The research results have been applied for the development of analytical and experimental approach to control safety of production environment in mines.
The article is devoted to development of methodology and digital technologies for assessing, forecasting and determining scenarios of geomechanical process evolution. A new digital technology is proposed for remote mining safety monitoring, which integrates a network personnel management system and expert subsystems for decision-making support taking into account geomechanical factors presenting risk of the mine roadway stability loss. Elements of the expert subsystems analyze data in real time, and are used to determine potential risks on basis of criteria and assessments of the production environment state in mines. It is proposed to identify the forecast safety indicators with the help of geomechanical models and by assessing scenarios of the “support-rocks” system stressstrain state evolution. In order the expert assessment of the rock massif and mine roadway stability, integral indicators of emergency potential risk for each geotechnical system elements are specified by values of informative parameters at a certain time point, as well as deviations rates of parameters from the equilibrium point over a period of time. Job safety is provided through the improved effectiveness of personnel interaction and its stricter disciplinary responsibility, as well as by making early decisions on keeping the mine roadways in a trouble-free condition.
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