Upward Segmented Backfilling in Multi‐Step Mining: Self‐Supporting Mechanism and Stability Control

ABSTRACT To address the challenges of self‐supporting backfill stability and surrounding rock control in multi‐step mining, this study proposes an innovative upward segmented backfilling approach tailored to the lithological characteristics of gold deposits. The method aims to optimise backfill structural integrity, mitigate ground instability risks, and ensure safe mining operations under complex multi‐stage extraction conditions. The method involved a combination of theoretical analysis, experimental research, and numerical simulations to investigate the self‐supporting and stability of multi‐step backfilling and explore the strength and structural characteristics of the backfill design. The results indicated that the determined backfill ratios were as follows: graded tailings (concentration 74%) at a 1:4 ratio, with an R 28 strength of 2.453 MPa; full tailings (concentration 64%) at a 1:4 ratio, with an R 28 strength of 1.75 MPa. The length and height of the backfill have a positive correlation with the self‐supporting strength of the backfill, while the width of the backfill has a negative correlation. For thin vein mining, priority should be given to the backfill height. It is recommended that the segmented height of thin vein mining should not exceed 20 m to improve the self‐supporting nature of the backfill.