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| Key parameter | Influencing factor | Corresponding measures |
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| Optimization of the support structure | Equipment performance | Increase the support strength and setting load. Design the hydraulic support ZZC10000/20/40 for solid backfill coal mining with a support strength of 0.82 MPa and a setting load of 8,322 kN |
| Optimize the support structure. Shorten the top beam length of the hydraulic support to 8,045 mm to reduce the distance of face roof under control |
| Design a full-seam tamping mechanism to achieve full-height compaction and increase the tamping capacity to 2 MPa |
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| Optimization of filling material formula | Mechanical properties | Adjust the sieving and crushing settings to crush the gangues down to sizes of 50 mm or lower to reduce the backfill body compression ratio |
| Filling material properties | Add water during transportation to optimize the moisture content of the solid filling materials, improve the material adhesiveness, and minimize the natural rest angle |
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| Preroof subsidence | Roof conditions | Install two layers of metal mesh in cases of false roof or broken roof |
| Backfilling technique | Parallel operations of mining and backfilling to reduce the time and span of unsupported roof before filling |
| Using hydraulic roof support to ensure prompt support and reduce roof deformation |
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| Tamping strokes | Backfilling technique | Ensure that the tamping counts for each backfilling are more than 10 strokes |
| Improve the initial loaded stress on the backfill body and reduce the compression ratio |
| Determine the initiation of the next cycle of coal extraction by the backfilling quality |
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| Dynamic monitoring of the filling ratio | Monitoring | Install equipment for monitoring support resistance, tamping force, and filling ratio to achieve real-time filling quality monitoring |
| system | Establish a step-by-step inspection system to check and rectify the filling quality |
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| Common measures | Operating specification | Establish complete training and assessment specifications and improve the technical capabilities of backfilling operators |
| Form a five-people team to perform backfilling alternatively and minimize the influence of personal reasons on the filling quality |
| Adjust salary based on filling quality to motivate operators |
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