Effect of longwall gob on distribution of mining-induced stress

With the development of a variety of gateroads within or close to gob, the effect of gob on the distribution of mining-induced stress is increasingly important. In view of the fact that the studies in this respect are few, Zhenchengdi colliery is investigated through theoretical analysis, physical modelling, numerical modelling and field observation. Several research means show that the more load the gob bears, the less the abutment pressure and vice versa. The longwall mining with split-level gateroad (LMSG) has an asymmetrical panel geometry, which results in asymmetrical stress distribution. It has larger gob stress and smaller abutment stress on elevating section side and smaller gob stress and larger abutment stress on non-elevating section side. The caved rock cushion is conductive to avoiding dynamic ground pressure behavior for the LMSG gob-side entry. The method for calculating the subsidence and rotation of the key blocks based on gob effect is obtained. The smaller the angle of break, the smaller the gob pressure and the smaller the gob edge pressure. The gob affects the stress concentration degree, the area and location of the stress concentration zones as well as the area of the yielded zone. The theoretical analysis, physical modelling, numerical modelling and field observation have a good consistency.