Verification Method and Engineering Practice for the Operational Characteristics of Paste–Solid Composite Backfilling Hydraulic Supports

Coal mine backfilling mining technology has developed rapidly in recent years. Composite backfilling technology, which integrates two single backfilling methods, is an approach that achieves multiple engineering objectives, including improved backfilling efficiency, enhanced stability of the backfilling body, effective control of surface deformation, reduced backfilling costs, and rational disposal of solid waste. As the core equipment of composite backfilling technology, the paste–solid composite backfilling hydraulic support is key to achieving the coordinated injection of both slurry and bulk materials in the composite backfilling working face. Verification of its operational characteristics is therefore necessary to ensure that the support meets the requirements for roof support and rear-area backfilling. This paper establishes an indicator system for the operational characteristics of the paste–solid composite backfilling hydraulic support and proposes assessment methods for six characteristic categories: structural, support, load-bearing, sealing, spatial compatibility, and backfilling coordination. For the Ji16-17-24100 working face at Pingmei No. 11 Coal Mine, the ZC13000/30/65D support was selected with a rated working resistance of 13,000 kN. The selected side-throwing belt speed is 3.5 m/s, within the calculated admissible range of 0–5.48 m/s, and the maximum allowable conveying resistance of the suspended belt is 33,640 N. The case study is a design-stage assessment under the specified engineering conditions; field performance should be evaluated using monitoring data.