Research on mechanism and parameters of reaming anchorage for grouted anchor cable in roadway floor

For design of reaming parameters of grouted anchor cables borehole in coal mine roadway of weak floor, the influence of reaming parameters, such as reaming diameter, length, number of segments and spacing, on the anchoring performance was investigated by conducting theoretical analysis, numerical simulation and laboratory tests, and the optimal reaming parameters for floor anchor cables borehole was ultimately determinated. The results show that the anchorage force of floor reamed anchor cables is positively correlated with both reaming diameter and segment length. The growth rate of anchorage force initially accelerates and then gradually slows down with the increase of reaming diameter, while it exhibits an almost linear increase with the segment length. Multi-segment reaming outperforms single-segment reaming, but beyond three segments, the improvement becomes negligible. The anchoring force of floor reamed anchor cables increases first and then decreases with the increase of reaming spacing, achieving the peak at 50 mm in space. By orthogonal simulations and pull-out test validation, the optimal reaming parameters were determined as a reaming diameter of 90 mm, a segment length of 100 mm, two reaming segments, and a spacing of 50 mm. The research results can advance the application of reamed anchorage technology in floor strata control of coal mine roadway.