Roof fracture and instability law of overlying strata in fully mechanized caving mining in ultra-close thick coal seams under the room mining goaf

Roof fracture and instability law of overlying strata in fully mechanized caving mining in ultra-close thick coal seams under the room mining goaf Journal of Mining and Safety Engineering . 2020, (6): 1180 -1187 . DOI: 10.13545/j.cnki.jmse.2020.06.012