Evolution path of mining-induced stress field in full-mechanized caving mining

In this paper, the evolution path of mining-induced principal stress field in top coal is studied based on the in-situ stress field on the 12309 working face of Wangjialing Coal Mine. The results show that vertical stress is bigger than minimum horizontal stress but smaller than maximum horizontal stress. The orientations of maximum and minimum horizontal stress are north-south and east-west respectively, and the stress ratios between horizontal and vertical of maximum and minimum horizontal stress are 1.52 and 0.45 respectively. The values of principal stress in top coal show a concentrated phenomenon and the stress concentration factor of maximum, intermediate and minimum are 1.90, 2.13 and 1.87 respectively. According to the evolution characteristics of principal stress field, the top coal is divided into four zones, including in-situ stress zone, stress-ascending zone, stress- released zone and roof-controlled zone. Finally, the evolution path of principal stress field is formed by selected feature points in the above zones.