Forecast of potentially dangerous rock pressure manifestations in the mine roadways by using information technology and radiometric control methods
I. Slashchov1, V. Shevchenko1, V. Kurinnyi2, O. Slashchova1, O. Yalanskyi2
1Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, Dnipro, Ukraine
2Dnipro University of Technology, Dnipro, Ukraine
Min. miner. depos. 2019, 13(4):9-17
https://doi.org/10.33271/mining13.04.009
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ABSTRACT
Purpose. To reduce risk of emergency and injury-risk situations while improving the methods for predicting stress-strain 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 (Po218) 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.
Keywords: geomechanical processes, permeability, filtration, radiation monitoring, rock mass modeling, forecast of geomechanical state
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