Supportingtechnology for large-section rectangular roadway over-collapsedcolumn structure

To ensure the safe and steadytraverse of the roadway across the collapsed column, withthe large collapse column in the second air return laneway in the fifth panel of Changping Mine as an example, the fracture mechanism of the ellipsoidal collapse column structural belt has been dissected based on fracture mechanics. Furthermore, limit equilibrium method has been adopted to arrive at the conclusion that the surrounding rock of the collapse column structure will be destroyed when the shear resistance is greater than the ultimate shear resistance on the periphery of the collapse column, thus it is believed that the lithology of the wall rock in the roadway crossing the collapse column must be changed. On this basis, a combined supporting method of pre-grouting in shallow wall rock + grouting in deep wall rock by flexible tubes +anchor cable net for the roadway across the collapse column tectonic zone has been proposed. Then, based on the grouting parameters and support parameters, the FLAC3D numerical simulation has been used for the supporting effect. Research indicates that the plastic zone area of wall rock greatly reduces, and the stress release rate slows down after the roadway excavation. Meanwhile, the maximum displacement of the top roof reduces by 460 mm, and the maximum displacement of roadway's sides decreases by 550 mm. Engineering applications show that the distortion of roadway wall rock tends to be stable after 24 d, and the displacements of two sides, top and plate of the roadway are controlled within 200 mm. The supporting effect of stope drift active workings is basically consistent with the FLAC3Dnumerical simulation results and can meet the engineering demand. © 2019, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.