Forecast of potentially dangerous rock pressure manifestations in the mine roadways by using information technology and radiometric control methods

Abstract

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.

New technical solutions in the field of protection and fastening of mine workings

“…In research, it is used for assessing the forecast indicators of the rock massif stress-strain state and possible scenarios of mine roadway stability loss. The analysis and evaluation of the parameters were carried out on the developed information system GEO-RS © [4][5][6][7][8]. The reliability and validity of the results is confirmed by the completeness and correctness of the source data, using proven methods of mathematical modeling of geomechanical processes.…”

“…The scientific foundations of the technology of active management of the state of the rock mass have been developed at IGTM NASU. An analytical description of the stress-strain state of the rock mass near the working excavation [4,5,[12][13][14][15][16][17][18], including taking into account: free gas in the rocks, water saturation and man-made cracks [7,[19][20][21], geological disturbances [7], extreme deformation of rocks [4,5], physicochemical destruction of coal [22] is worked out by scientists of the institute. A model, which has been verified by numerous experiments in mines, has been developed.…”

Development of digital technologies for the systems of remote mining safety monitoring

“…Elements of the expert subsystems analyze data in real time, and, if necessary, are used to determine potential risks on basis of criteria and assessments of the state of the production environment in mines including use of mathematical apparatus of fuzzy logic [10][11][12]. Advantages of the expert subsystems are their ability to forecast geomechanical and gas-dynamic processes in the rock massif and negative consequences caused by these processes in mine roadways (rock falls, destruction of roof supports, floor heaving in the roadways, etc., [13,14]), as well as accumulation and storage of necessary knowledge in the database. In particular, in order to assess safety of jobs by geomechanical factor, the following data are calculated and stored in the database: local models of the rock massif typical behavior, nomenclature and power characteristics of supports, physical and mechanical properties of rocks and sets of the most common mining and geological conditions of the field development.…”

“…The expert assessment of the roadway roof and floor state is most effective for combining visual (Fig. 4), instrumental and geophysical control with numerical analysis of the rocks stress-strain state by the finite element method [1,14,26]. This approach allows, on the one hand, to verify accuracy of the calculations, determine stage of the deformation process, and combine objective data of the instrumental observations with the data obtained by calculation using local models of the rock state.…”

Development of methods and software algorithms for state forecast of the ultimate stressed rock massif

“…As a consequence of the massif dangerous manifestations, there is an increase of methane emissions, an increase of the mixture radioactivity, dust content, pressure and speed of the outgoing air jet, acoustic vibrations, electromagnetic radiation, etc. [1][2][3][4][5][6][7]. Existing methods for assessing of the coal-rock massif hazardous state in mining are based on the analysis of the main informative parameters that determine the gasdynamic phenomena: the magnitude and structure of the rock pressure, the output of the gas contained in the coal, the physical and mechanical properties and the state of the coal-rock massif.…”