Research on Parameter Optimization of Active Advance Support with Reinforced Anchor Cables for Mining Roadways

Single hydraulic props are widely adopted as passive advance support for working faces with hard roofs in deep mining, yet this support scheme has prominent drawbacks including insufficient overall bearing capacity, heavy labor burden for frontline workers and low level of mechanization matching. Taking the transportation roadway of fully-mechanized mining face in Xinji No.1 Coal Mine as the engineering background, this paper develops a complete set of active advance support technology centered on grouting-reinforced anchor cables. By virtue of FLAC3D three-dimensional numerical simulation, multi-scheme comparative optimization is carried out on three core equipment parameters of reinforced anchor cables, namely pre-tension force, total length of steel strand and layout row spacing. The optimal matching parameters are determined as follows: total anchor cable length of 8200 mm, transverse row spacing of 2000 mm and tension preload of 200 kN. Combined with the composite anchoring structure of end anchoring plus full-length anchoring and double-liquid grouting construction technology, an integrated mechanized construction system for advance support is established. The monitoring results of underground industrial tests indicate that the maximum roof subsidence of the roadway reaches 270 mm, the maximum relative convergence of roadway ribs is 230 mm, and the maximum actual working load of anchor cables is 250 kN. In the monitoring of roof rock separation, the maximum separation at shallow base points is 21 mm while that at deep base points is merely 6 mm. On the premise of guaranteeing qualified surrounding rock control effect, the active advance support scheme with grouting-reinforced anchor cables realizes mechanization upgrading of advance support procedures and greatly reduces the labor intensity of underground workers in transporting and erecting support components.