Study on numerical simulation for the fracture law of gob-side entry retaining roof

The geological conditions of haulage roadway of the working face 1528 in GeQuan Coal Mine, which belongs to the JiZhong Energy Group Co., Ltd., and the research findings of Key Stratum Theory was taken into consideration, based on which established a mechanical model could reflect the basic features of rock stratum and made a profound investigation on the form and conditions of the fractures on main roofs. A systematic study on the stress, deformation, and damage characters of fractures on main roofs beyond a retained entry has been made by the numerical simulation. The simulation shows that the deeper the fracture is in the rib, the greater the differences between dimension of compression and deformation will likely be, and the greater the influences on the stability of surrounding rock will it has. At the same time, smaller is the overhanging beam in mined-out area, more beneficial to roadway maintenance. On a certain deformation of main roof, it creates subsidence that is great difference in different position of a roadway. The subsidence near those mined-out areas is much more than those near the ribs. The application of a strong and effective measure could help cut the roof out and assure its stability.