Study on deep and shallow hole grouting reinforcement technology of coal rock interbedded composite roof in coal mining face

In order to solve the problems of broken loose, separated layer and falling off, overall leaking gangue serious and even large area roof caving in coal rock interbedded composite roof, taking 9104 working face of Xinyuan Coal Mine as the engineering background, through the method of field investigation, theoretical analysis and numerical simulation, the instability failure mechanism of coal rock interbedded composite roof in working face was studied. The basic treatment areas, key treatment areas and important treatment areas with length of 3 m, 25 m and 23 m respectively were divided, the main treatment idea of regional reinforcement and key reinforcement of composite roof in working face was determined. On this basis, the regional composite advance pre-grouting reinforcement technology of "two deep holes, one shallow hole, two materials, three regions" was put forward. According to the field engineering practice, engineering analogy and theoretical calculation formula, the grouting materials and key grouting parameters were determined. The field engineering application shows that this technology can effectively solve the problems of large area leaking gangue, roof caving and mining obstruction caused by the broken and soft characteristic of coal rock interbedded composite roof, so as to ensure the safe mining at normal speed in working face.