Abstract： As a new mining technology, separated layer grouting has been used in various mining areas of China in recent years. The laws of motion and deformation in the rock layer were firstly studied, and then the separation position of overlying rocks was found according to the theory of arch-beam balance. By filling medium in the upper separation layer, such as sand, fly ash, desulfurization gypsum, coal gangue, the movement of the upper separation layer could be reduced to achieve the goal of controlling and stabilizing the surface. The judgment of key layer was one of the most important links for grouting. The judgment method of key layer of separated layer grouting was studied in this paper and provided a theoretical basis for the design of grouting filling parameters.
