Calculation and monitoring analysis of stress distribution in a coal mine gob filled with waste rock backfill materials

Crushed backfill materials are used to backfill the gob during solid backfill mining (SBM). Thus, the stress distribution in the coal mine gob is different from that found when using other methods including caving and paste backfill mining. The compaction properties of crushed waste rock backfill materials (WRBM) with different particle sizes were tested using a test machine and a self-made compaction device in order to analyze the stress distribution in the coal mine gob. Moreover, based on the stress-strain relationship for such WRBM, a method for calculating the stress distribution in a gob filled with backfill materials was proposed and a stress calculation model was established. In addition, taking engineering practice as a case study, stresses in the gob of an SBM-worked panel were calculated, measured on site, and analyzed. The calculated result is consistent with that measured on site, thus verifying the feasibility of the research. In addition, the influences of four primary factors including backfill material particle size, mining height, mining depth, and coal seam dip angle on the stress distribution in the gob were analyzed.