Abstract: This study investigates the abrasion effects of coarse aggregate-modified paste on 16Mn steel elbow pipes used in mining pipeline backfill systems. Incorporating coarse aggregates into paste backfill is an effective strategy to increase the backfill strength and reduce costs. However, it increases the risk of abrasion in pipeline elbows, which can shorten pipeline life and compromise slurry transport safety and efficiency. Elbow sections are also vulnerable to wear from flow direction changes and particle impacts; thus, understanding these effects is key to pipeline reliability. The objective of this study is to establish the abrasion influence laws of coarse aggregate-modified paste on elbow pipes. To this end, the study uses contact stress and indentation depth as key indices to systematically evaluate pipeline wear severity. Using Hertz contact theory, quantitative models are developed to describe the interaction between spherical coarse particles and the inner wall of the elbow pipe. These models enable the calculation of contact stress and indentation depth as functions of particle size, sliding velocity, and elbow curvature. The study also employs a combination of gray relational analysis and the SHapley additive exPlanation (SHAP) method to determine the contributions of various factors to the abrasion process. Specifically, it investigates the influence of coarse aggregate particle radius, slurry sliding velocity, and elbow pipe radius on wear. Gray relational analysis provides a measure of the correlation between each factor and the abrasion indices, while SHAP analysis quantifies the impact of each factor in a predictive model analysis. The results reveal clear trends in how the influencing factors affect abrasion. The analysis identifies sliding velocity as having the most pronounced effect on contact stress and indentation depth, with both increasing as the coarse aggregate radius and sliding velocity increase. This relationship follows an approximate power-law form, indicating nonlinear sensitivity to changes in particle size and velocity. Larger elbow pipe radii (gentler curvature) lead to lower contact stresses and shallower indentations for particles of a given size and speed. The peak contact stress is 105.9 MPa, which is approximately 30.7% of the typical yield strength of 16Mn steel (approximately 345 MPa). This indicates that under these conditions, the pipe wall does not experience plastic deformation due to individual particle impacts. Instead, wear is attributed to repetitive impacts causing fatigue damage. Observations of worn pipe surfaces suggest that the dominant abrasion mechanisms are fatigue cracking and thin-layer spalling. Small cracks initiate and propagate under cyclic loading, ultimately causing thin layers of material to spall off the surface. In conclusion, the study clarifies the hierarchy of factors influencing abrasion in pipelines transporting coarse aggregate-modified backfill and identifies the dominant wear mechanisms. These insights provide guidance for mitigating pipe wear in practice. For example, optimizing the elbow geometry (increasing the radius of curvature), selecting the appropriate aggregate size distribution (to limit the effect of large particles), and applying surface treatments or coatings to the pipe wall are recommended to mitigate abrasion effectively. Implementing these strategies can significantly extend pipeline service life and reduce maintenance requirements in abrasive slurry transportation.