Abstract:The phenomenon of filling body delamination caused by multiple filling has brought many unknown factors to the follow-up support design of the mine. In this paper, three lime sand ratios of 1:4, 1:6 and 1:8 are set by indoor experiment; 66, 67 and 68 mass concentrations; 1. Two and three layers are arranged to combine 27 groups of filling bodies. Uniaxial compression tests were carried out on each group of backfill to explore the influence of delamination characteristics on the strength of backfill, and combined with FLAC3D software, the "interface" function was used to analyze the changes of stress state and failure mode of different layered backfill when conducting uniaxial compression tests. The results show that: (1) The delamination characteristics will affect the corresponding relationship between the lime sand ratio, mass concentration and the strength of the filling specimen. The greater the number of delaminations, the smaller the increase of the strength of the filling specimen with the lime sand ratio and mass concentration; (2) The delamination interface will change the failure mode of the specimen under uniaxial compression. When the number of delaminations increases from one to three, the failure mode changes from tensile failure parallel to the loading direction to shear failure close to the upper delamination to tensile failure through the two delaminations. At the same time, the shear dislocation phenomenon at the interface is more obvious.