The correspondence of angular and linear parameters of the undermined rocks displacement and the crustal movement to their values determined according to the normative document has been established. Based on the surveying observations over the reference points movement on the earth surface and the stope face advance, the empirical curve of the trajectory of the earth surface maximum subsidence is determined from the points of maximum subsidence. The curve of the maximum subsidence of the earth surface points when removing the stope face from the face entry has been experimentally established, which allowed to determine the location of the point of the beginning of the crustal movement and the dimension of the stope mine working corresponding to this situation. The coordinates of the characteristic points of the earth surface subsidence above the stope face have been determined. A unified method has been developed for determining the angular and linear parameters of the undermined rocks displacement for the two stages of shift troughs formation on the earth surface. The nonconformities have been established between the recommended parameters and the experimental data normative documents during the anthracite seams mining.
Purpose: to establish a possible correspondence between metamorphic processes with artificial thermal destruction of coals and their ashing in order to identify the components of mineral impurities that can affect the manifestation of the hazardous properties of coal mine seams. Methodology is based on a comparison of metamorphic processes that took place at a certain temperature mode in the bowels of the Earth and the production of artificial coals and their ashing. Results: The research made it possible to reveal the important role of mineral impurities in the formation of the hazardous properties of coal seams. This is due to both the significant possible content of mineral impurities in fossil coals, and the simultaneous presence of the main components that determine the hazardous properties of coal seams (carbon, hydrogen, sulfur, oxygen and moisture), both in the organic and in the mineral parts of fossil coals. To improve the regulatory framework for the safe conduct of mining operations, it is necessary to take into account features of the properties of fossil coals due to the presence of mineral impurities in them. In modern regulatory documents on the safe conduct of mining operations, in general, several indicators are used without proper scientific justification: the mass yield of volatiles during the thermal decomposition of coal, the volumetric yield of volatile substances, the thickness of the plastic layer and the logarithm of the electrical resistivity of anthracites. Their values are related to the dry ash-free mass of organic matter only. This excludes consideration of the influence of mineral impurities on the manifestation of the hazardous properties of coal mine seams during mining operations. In many cases, the content of moisture and sulfur is a criterion for the manifestation of hazardous properties of coal seams. They belong to the integral components of both organic and mineral constituents of fossil coals. The share of mineral impurities in the coals of individual coal seams can be more than 40%. The presence of oxygen, hydrogen, sulfur and moisture in mineral impurities significantly affects the manifestation of the hazardous properties of coal seams during mining. The content of mineral impurities in fossil coals in engineering calculations can be determined on the basis of the ash content of coals according to known empirical relationships, corrected for the content of total sulfur and, in some cases, carbon dioxide. Scientific novelty: the significant influence of mineral impurities in fossil coals on the manifestation of hazardous properties of coal seams during mining operations has been proved. Practical value: the results obtained allow substantiating the methodology for the combined use of the composition of organic and mineral components of fossil coals for a reliable forecast of the manifestation of hazardous properties of coal seams and improving the regulatory framework for their safe mining.
A theoretical scheme of gas release from the coalbed under production by treatment workings has been developed. The sizes of zones of different intensity of gas release from the working thickness are set according to the characteristic points of muld shift of the earth's surface. Total amount of releasing gas is determined by the area of the developed space, over which there is an intensive movement of the mined coal. The formation of this area is associated with the development of cleaning operations within the boundaries of the excavation site and the speed of movement of the treatment face. During the development of the theoretical scheme, several assumptions were made, the validity of which was verified on the basis of experimental data obtained in the conditions of four mines at fifteen excavation sites. Coal seams with coals of grades G and A were worked out by them at a depth of 300-1195 m, the capacity of coal seams was 0.90-2.20 m, cleaning works were carried out at a depth of 300-1195 m, the length of the lavas was in the range of 74÷270 m. The monthly movement of the treatment faces and the amount of gas released during this period were taken into account for each excavation site. It is established that the relative gas release per unit area of the developed space remains a fairly constant value for some mining and geological conditions, if the total amount of gas is attributed to the area that determines the active movement of rocks over a moving treatment face. This allows you to use the previously obtained results of determining the categorical danger of mines by relative gas release per ton of coal production in terms of improving the forecast of gas release from the coalbed under production more efficiently.
The parameters are established in the work of the stope mine workings and rocks displacement, which correspond to the maxima of gas emission into the gas drainage boreholes. The angular and linear parameters of the crustal movement and rocks displacement have been calculated with the use of empirical dependences. These parameters correspond to the maxima of gas emission into the gas drainage boreholes. The obtained positive results for determining the possible areas of maximum gas emission allow us to recommend the empirical dependences for calculating the angles of maximum subsidence and complete displacements at the stage of stope works development, as well as the dimensions of the stope mine workings, at which the processes of rocks displacement reach the earth surface. The established relations between the gas drainage boreholes location and the rocks displacement zones with discontinuity make it possible to design the optimal schemes of draining-out of gases from the gas-and-coal deposits. For the first time, three independent methods have been used to determine the changes in dimensions of rocks displacement zones with discontinuity after the primary main roof squeezing until the formation of stable upper boundaries of these zones.
Purpose: to establish the quantitative dependences of gas emissions from the forged coal seam outside the operated areas on the degree of development of treatment works in the mine field. Methodology: the method provides for a comparative analysis of experimental data obtained during the development of several benches in the wing of the minefield. Results: the theoretical model of formation of zones of possible gas evolution from the forged coal seam outside the operated excavation sections at discrete increase of the produced space of the mine field wing by the length of the spent lava is considered. The maximum gas emission both on the excavation site and outside it is associated with the subsidence of the main roof as the development of treatment works and the removal of the treatment face from the split work. Activation of the shift of the counterfeit coal seam outside the excavation section causes an intensive increase in gas evolution, which can significantly exceed its release within the operated excavation section. Such circumstances, to a large extent, affect the safety of mining operations and indicate the need to improve the regulatory framework for the forecast of gas emissions in coal mines. Scientific novelty: statistical processing of experimental data allowed establishing the dependence of the level of gas emissions in mine workings and degassing wells simultaneously from three main factors – coal production and the degree of development of treatment works at the excavation site and within the minefield wing. Practical value: the analysis of long-term experimental results of observations of gas evolution from the forged coal-bearing stratum within the exploited sites and outside them is carried out. With sufficient development of treatment works in the wing of the mine field, the gas emissions outside the operated excavation site can significantly exceed the gas emissions in the site workings and degassing wells.
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