JUSTIFICATION OF THE METHOD OF DETERMINING THE DESTRUCTION TIME OF THE ROOF LAYERS OVER THE MANUFACTURED SPACE OF BENCHES TAKING INTO ACCOUNT THE CRACK RESISTANCE OF ROCKS

Purpose. Study of the process of destruction and collapse of rocks of the main roof during cleaning operations in difficult mining and geological conditions. Justification of the method of determining the time of roof destruction taking into account the crack resistance of rocks. Method. The method of laboratory studies of rock fracture toughness; the method of physical modeling of rock mass collapse processes over the created space, analytical studies of the process of layering and destruction of rock mass. Results. As a result of laboratory experiments, the results of fracture viscosity, specific energy of crack formation for sandstone were obtained. As a result of physical modeling studies, analytical calculations, dependencies were established: the step of the collapse of the main roof, the height of delamination, for each scheme under different technological and geological working conditions, and the time of destruction of the roof layers, taking into account the crack resistance of the rocks. A justified expression for determining the height of delamination taking into account the crack resistance of rocks. A well-founded method of determining the rate and time of destruction of the roof layers above the created space, taking into account the crack resistance of rocks. Reasoned formulas for determining the parameters of primary and periodic collapse of roof layers over the created space, taking into account the crack resistance of rocks in complex mining and geological conditions. Scientific novelty. For the first time, the dependencies of the main roof collapse step were established for each scheme, under different technological and geological working conditions, taking into account the crack resistance of the rocks. For the first time, the dependence of the height of delamination, taking into account the crack resistance of rocks, was established. For the first time, the dependence of the time of destruction of the roof layers, taking into account the crack resistance of the rocks, was established. Practical significance. The practical significance lies in forecasting the processes of layering, destruction and collapse of the main roof rocks in the complex mining and geological conditions of working out coal seams. Establishing the time of destruction of the immediate and main roof will allow determining the nature of the destruction of the roof, and will allow adjusting the further management of the roof. Key words: main roof, crack resistance, fracture toughness, specific energy of crack formation, delamination height, roof collapse step, time of destruction of rock layers of the roof