Investigation on rational width of coal pillar and roadway support in isolated panel of extra-thick coal seam

The methods of numerical simulation and on-site measurement is used to analysis reasonable coal pillar width (CPW) and roadway support in isolated panel of extra-thick coal seam. Numerical modeling shows that a maximum vertical stress in isolated panel is 32.9 MPa, and stress concentration factor reaches 2.99, which is more affected by the mining of adjacent panel, and the peak stress on both sides is higher. By comparing the failure and deformation characteristics of different pillar widths, it is shown that a 6 m pillar can reach the load requirements of overlying strata and ensure that the roadway is in an undamaged and controllable environment. According to the asymmetry of surrounding rock deformation, the final joint control technology of asymmetric anchor cables, high intensity anchor cables, and coal pillar grouting is proposed and get good control effect on site. The research results provide guidance value for surrounding rock control under similar geological condition.