Study on the technology of roof cracking caused by static crushing agent in Xiaochang Coal Industry

In view of the difficulty of hard roof caving in mine, taking the 30217 headentry of Xiaochang Coal Industry of Jinneng Holding Group as the engineering background, the static crushing agent (SCA) was used for roof caving. The practical effect of SCA was studied through the combination of experimental analysis, numerical simulation and engineering practice. The results show that the radial swelling pressure of SCA increases with the increase of inner diameter of steel pipe. Generally, the radial swelling pressure at the bottom of steel pipe is greater than that in the middle. The larger the inner diameter of steel pipe, the greater the difference between the radial swelling pressure at the bottom and the middle of steel pipe. When the inner diameter of steel pipe is the same, the radial swelling pressure of steel pipe also increases with the increase of constraint degree. After the action of SCA, the roof subsidence of 30217 headentry increases by about 148 mm. After the presplit hole of 30217 headentry is filled with SCA, the roof collapse step of auxiliary 30217 working face is reduced by about 10 m. The successful application of the project has a reference significance for mines with the same mining problems.