Pop-upcavities

Abstract

Theobject of this paper is research into the understudied for now process of cavities, preserved in the sub-surface coal-bearing strata in the Donets Basin, moving from the places of their original location towards the surface. Case study approach. The recorded cases became known as pop-up cavities that occur in coal mining practice are analyzed. Prediction computation of stage-by-stage popping-up of relatively undestroyed mine opening (cavity) in coal-bearing strata of different strength is made. Research results. The conditions and factors contributing to the popping-up of the remaining cavities towards the overlying levels are determined. Relations of the popping-up cavity height, its initial size and depth of location from the surface, the strength of rock layers and the potential triggers are determined. With increase in proportion of low-strength rocks within the solid the height of cavity increases and presence of strong rocks minimizes the height of cavity popping-up to and including its preservation. Any subsequent cavity pops-up to lower height and with smaller dimensions. The number and height of popping-up in each particular case are individual. The scientific novelty. Popping-up of cavities implies continuation of the process of ground movement after seemingly complete elimination of the cavity due to caving of it by overlying rocks. Evaluation of the remained mine working (cavity) possible caving should not be limited to a stage of its self-cleavage and its popping-up should be taken into account. Practical importance. The necessity of this process to be taken into account in evaluating the danger level of the surface areas, damaged by abandoned mine workings at shallow depths due to their potential caving capability is justified that improves prediction accuracy.