Based on the shear strength model of underground paste filling interface and shear test research

The shear performance of the interface between rock and cemented paste backfill (Rock-CPB (P)) and the interface between cemented paste and cemented paste (CPB (R) -CPB (P)) is of great significance to the safety and stability of underground backfill. Based on the interface adhesion force and ploughing force, a theoretical model of shear strength of filling interface suitable for underground mining is derived. The model considers the influence of surface roughness coefficient, physical and mechanical parameters and normal stress of rock or filling body on the interfacial shear performance. The correctness of the model is verified by a series of direct shear tests. At the same time, the relationship between interfacial shear strength and concrete surface roughness coefficient, normal stress and curing age was explained by direct shear test. The results show that the interface shear strength and shear displacement have typical elastic-plastic characteristics. The shear strength and interface roughness coefficient increase linearly. With the increase of curing age from 3d to 7d, the shear strength of the interface shows an increasing trend. The shear strength and normal stress of the interface increase with the Allometric function. The grey correlation theory is used to analyze the primary and secondary effects of various factors on the interface shear strength. The results show that the normal stress has the greatest influence on the shear strength, followed by JRC, and finally the curing age. Finally, the applicability and limitations of the theoretical model and test are discussed.