Considered are the thermodynamic conditions on the surfaces generated in coal cracks in the process of its destruction. It is shown that the temperature at the surface of cracks on the stage of destruction is comparable with the melting temperature of coal and ignition of methane. Ratios for the assessment of the development phase transitions on the surfaces of coal cracks. It is shown that the rate of methane in proportion to the total surface of the pieces of coal at de-struction. To reduce the amount of methane generation it is recommended to reduce the load on the breakage face.
The rock in a rock mass is in a tense equilibrium. This equilibrium is usually broken when mining operations are stopped. There are many theories related to rock pressure in the stoping zone. Obviously, the solution of problems on this subject is associated with the study of deformation and dislocation processes of rocks in the workings and mine shaft. Since it is difficult to conduct grandiose full-scale experiments, these problems have to be solved by new developed methods, which are very universal and informative.
Prospective directions of improving technological schemes of shale formation development under aquifers, providing technical and environmental safety of underground mining works are analyzed. The expediency of using development systems with parameters that ensure the smooth deflection of the undermined massif without the formation of cracks that unite the aquifers is substantiated.
The influence of various factors on the condition of the edge zone of the coal seam ahead of the face during the development of flat seams is assessed. All the variety of factors can be divided into mining-geological and mining-technical. Of mining-geological factors, the greatest influence on the coal deformation in the peripheral zone have such factors as power, depth of development, dip angle, presence of interlayers, of mining-technical - face length, speed of its movement, development system, type and power characteristics of the support, method of rock pressure control.
A mathematical model of interaction of a multilayer massif with a thin coal seam, including initial resolving differential equations and boundary conditions, has been obtained. The developed algorithm of numerical solution is implemented in a computational program in which the input parameters are geological characteristics of the main and immediate roof, stiffness coefficient of the coal seam in the massif and the law of its change in the edge zone, stiffness coefficient of soil rocks, stiffness coefficient of fill material, layer thickness and ultimate deformations of the roof. Accordingly, the output parameters of the calculation program are: the response of the coal seam to the action of the load from the overlying massif (support pressure), vertical and angular displacement of the roof layers over the coal seam, vertical and angular displacement of the roof over the mined-out space, the ultimate span of the roof.
A method for controlling the rock mass condition for the working faces using jetting units under unstable roof conditions has been developed. The necessity of increasing the rate of advance of the working face and the use of backfill of the mined-out space to ensure rock stability and uniform loading of the edge part of the formation has been proved. A formula for calculating the critical value of the filling mass suppression, which takes into account the caving step of the main roof, the loosening ratio, the thickness of the immediate roof rocks and can determine the compression properties of the filling mass by modern methods, taking into account the rate of advance of the face and the size of the squeeze zone, has been proposed. The proposed methodology substantiates an increase in the rate of face advance up to 4-6 m/day and the load on the working face by 30%.
The results of scientific research of the Department of Underground Mining of Mineral Deposits, carried out in 2000 on problematic issues of underground mining of coal, shale and salt deposits, are presented. The requirements to the technological schemes of reservoir development in areas with limited size when using high-capacity mechanized mining complexes are formulated. Ways of increasing the efficiency of mining thin coal seams with the use of jet installations are proposed and substantiated. The causes of dynamic collapse of the roof rocks in the lower faces of the layered systems of development are investigated. Conclusions are made about the most promising ways of development of technogenic and oil and gas fields. Recommendations on underground coal combustion for steam and power generation have been developed.
