SUBSTANTIATION OF PARAMETERS OF ROOM-AND-PILLAR MINING WITH REGULAR EXTRACTION OF PILLARS AND ROOF CAVING AT A LARGE DEPTH
Effective performance of mining operations is largely determined by the choice of safe technology of extraction, taking into account the real geomechanical processes occurring in the rock mass. The use of open stope systems is determined by increased technological risks associated with ensuring the stability of the rock mass. The main production method that increases the safety of extraction operations in these geotechnologies in conditions of considerable depth is the multiple increase in the sizes of various types of pillars, which leads to a significant increase in the losses of the mineral. Known methods of development with stowing of worked-out space, ensuring a high level of ore extraction, increasing the stability of mine structures under rock bump hazard conditions and high safety of mining operations, are characterized by an unreasonably high cost of production and erection of an artificial massif. Production costs of medium and low value minerals are not justified, thus referring these geotechnologies to the category of unprofitable. A promising direction under these conditions is the development and justification of new resource-saving technologies combining the development systems with different methods of rock pressure control, which allow us to increase the advantages and minimize the shortcomings of each of them. Therefore, the development of scientifically justified options and parameters of combined geotechnologies is an urgent task for the further development of safe and efficient mining methods requiring the detailed study. The aim of the study is to develop and substantiate the parameters and conditions for the safe application of the board-and-pillar development system in combination with the roof rock caving. The main study method is a three-dimensional finite element simulation of the stress-strain state and stability of a rock massif in structural elements of underground geotechnology. The basic parameters of temporary columnar pillars and the area of safe application of technology are established for a depth of 1000 m in massif with gravitational distribution of initial stresses.