Substantiation into "rock massive - Underground gasifier" system adaptability of Solenovskyi site in the Donetsk coal basin

Purpose. Research on stress-deformed state of rock massive around underground gasifier taking into account the change in the continuity of the roof rocks and the thermodynamic stresses in them. Methodology. Conducting analytical studies was based on the accepted physical and mathematical models, for the development of which the rock massif movement theory of Professor A. V. Savostianov is adopted, reflecting the features of the rock strata behavior over the gasifier (stratification, the fractures and stratification cavities formation, layers movements relative to each other). Findings. Multivariant calculations of the stress-deformed state of the rocks around the underground gasifier are performed with the establishment of the load diagrams parameters for the sub-layers of the massif, depending on geological, technological and temporal factors. Originality. Dependencies of the underground gasifier bearing pressure zones distribution on the adjacent roof level of the coal seam were established, taking into account gasification channel length (30 and 60 m) and the velocity of combustion face advance from 0.5 to 2.0 m/day. For the first time, dependencies representing the rock layers subsidence parameters in the underground gasifier roof from geomechanical factors, as well as thermal stresses along the gasification channel length and the velocity of combustion face advance, were obtained. Practical value. A mathematical mechanism was proposed for the determination of stresses in various rock massif sections in case of borehole underground coal gasification in order to establish the conditions for the "Rock massive - underground gasifier" system adaptability, taking into account geomechanical factors and thermal stresses along the gasification channel length. The obtained dependencies make it possible to predict the necessary velocity of the combustion face advance to ensure technological effectiveness of the gasification process.