Study on the shape of the space stress arch shell in steeply dipping coal seam mining

The evolution law of the spatial stress field in roof,and the space form of surrounding rock structure after the coal seam mining in steeply dipping seam mining is unconventionally complex compared with the mining of gently-in- clined coal seam,which is due to the buried conditions of the steeply dipping seam. Based on the results of the physi- cal simulation experiments and numerical simulation of steeply dipping seam mining,the basic mechanical characteris- tics of the space shape of arch shell after coal seam mining was analyzed. It revealed that the space shape of arch shell after coal seam mining,which is belong to mining disturbance,is an optimal structure. The shell structure is symmetric along coal seam strike but not along the inclination of coal seam. Accordingly,considering waste rock filling effect,the model of stress arch along coal seam strike and inclination of coal seam is established. The rational axis equation along coal seam strike and inclination of coal seam is obtained. The results show that when working face advancing distance is far greater than the length of the working face,the shell structure configuration is independent with the working face advancing distance. The arch height and span length of symmetric stress arch increase firstly and decrease later along the inclination of coal seam. The maximum caving height is in the middle and upper part of the inclination direction, and the arch height and span length of symmetric stress arch is the largest in that zone.