Effect of interface roughness on mechanical properties of layered cemented tailings backfill

Research on the roughness parameters of the layered interface of the layered cemented tailings backfill (LCTB) is of great significance to improve the cementation quality of layered layers and reduce the strength reduction rate caused by layering for the safety and stability of the mine structure. Using the sedimentation mechanism of tailing sand particles, different roughness interfaces with different solid densities (SDs) and number of layered layers were designed, and the influence mechanism of interface roughness on the cementation quality of layered layers was studied by using uniaxial compression test, surface roughness detection and particle size detection. The results show that the existence of stratified surfaces can significantly reduce the uniaxial compressive strength (UCS) of the LCTB, which is defined here as the Stratified reduction rate (SRR).When the number of stratified layers is constant, the strength reduction rate caused by stratified layers decreases with the increase of SD, and the increase of SD will increase the shear resistance of the coarse particles in the slurry, making it less prone to segregation and subsidence. As a result, the larger the proportion of coarse particle size distribution on the layered surface, the macroscopic surface roughness increases. The SRR has a good linear fitting relationship with surface roughness Ra, and the SRR decreases with the increase of Ra, indicating that to a certain extent, the greater the surface roughness of the stratified plane, the better the cementation quality of the delamination surface, and the weaker the reduction effect of the delamination on the strength of the LCTB.