Failure Mechanism and Control Techniques of Reused Roadway in an Isolated Coal Barrier Pillar

摘要

Reused roadway in double-U shaped layout with an isolated barrier pillar subjects to two adjacent panels mining and has large deformation. In order to keep the reused roadway stable in its service life, numerical simulation, theoretical analysis and field observation were applied to investigate the deformation rule and failure mechanism of surrounding rock during mining period. Research results show that low strength and high stress difference environment is a fundamental reason of shear failure, different loading and unloading path in both ribs of roadway is the primary reason of asymmetric failure, and performance of bolting support is critical for the roadway stability. Therefore, control techniques of reused roadway are put forward that 1) high-strength and yielding bolts support the roof and ribs to adjust to massive convergence of roadway; 2) yielding counter-pulled cables reinforce small-pillar rib to strengthen the stability of small coal pillar; and 3) hydraulic expansion bolts support the floor. The results have been successfully applied to a field trial.