Study on stress state of immediate roof above backfill area in gob-side entry retaining and its application

In order to overcome the problems with the immediate roof control of gob-side entry retaining (GER) in a fully-mechanized top-coal caving longwall,a compound roof longwall and other soft cracked longwall,an elastic damage mechanics model of immediate roof above roadside backfill area (IRRBA) in GER was established,the stress distribu- tion expression of IRRBA in GER was deduced,and the stress distribution evolution of IRRBA in GER was researched based on the space-time movement characteristics of IRRBA in GER. Then,the tensile stress depth and horizontal dis- location region calculation formulas of IRRBA in GER,and the corresponding evolution laws were obtained. Results show that the stress state of IRRBA in GER are associated with the main roof rotation angle and the immediate roof damage variable,and that the tensile stress depth decreases and the horizontal dislocation region increases with the in- crease of main roof rotation angle. Combined with the 3107 longwall engineering geological conditions of Xinyuan Col- liery,the dynamic regional consolidation control countermeasures for IRRBA in GER were put forward. Field practice shows that the application of control countermeasures has achieved an expected effects for the subsidence of IRRBA and surrounding rock stability control in GER.