Abstract: Waste rock backfill mining,as an efficient mining method,is widely applied in the industry but faces challenges
such as poor self-supporting capacity of the backfill,difficulties in roof contact,and insufficient strength. Collaborative
backfilling with waste rock and tailings slurry can address these issues. Conventional methods involve hoisting underground
waste rock to the surface,mixing it with tailings slurry to prepare a composite backfill,and then transporting it back underground,foundation for the resource recovery of mine waste and the research and development of green mining technologies.
which is complex and increases transportation difficulties. To overcome these limitations,this study proposes a novel
collaborative backfilling method that integrates waste rock backfilling with tailings slurry roof-contact filling,aiming to simplify
the backfilling process and enhance the performance of the waste rock backfill. Based on the engineering context of the Tieling
Hongyin Iron Mine,this study employs theoretical calculations and numerical simulations to systematically evaluate the feasibility
of this method in terms of stope backfilling effectiveness and surface subsidence control. The influence of waste rock proportion
on the stress distribution within the backfill,roof displacement,and surface subsidence is thoroughly investigated. The results
demonstrate that increasing the tailings slurry proportion significantly improves the strength and stability of the backfill.
The internal stress of the backfill is predominantly compressive,exhibiting a distribution pattern of "lower at the periphery and
higher in the center," with stress concentration prone to occur at the interface between tailings slurry and waste rock. An increase
in waste rock proportion enhances the compressibility of the backfill,weakening the support to the roof and surface,leading
to greater displacement. When the waste rock proportion is kept below 70%,the backfill effectively controls roof subsidence,
preventing large-scale plastic failure. Under these conditions,the maximum tilt deformation,curvature and horizontal deformation
of the surface monitoring line remain within the safety limits specified by regulations,further validating the feasibility
of the proposed backfilling method. By optimizing the efficient utilization of waste rock,this study provides a new theoretical