Large-deformation mechanism and control technology of roadway injointed and brittle and extremely thick coal seam

Aiming at strong mining pressure behaviors and large deformation of the extremely thick and brittle coal seam in Luxin Mining Area, comprehensive method including theoretical analysis, numerical simulation and industrial test were adopted to research the deforming mechanism and controlling method.The large deformation mechanism of roadway under dynamic load were the spallation, cleavage of coal seam and the dilatancy induced by the synthetic action of strong unloading and dynamic load. DEM dynamic modelling showed that dynamic load intensity played the most important role in the roadway deformation，large roof separation appeared and load bearing structure failed when dynamic load reached 15 MPa, while in excess of 25 MPa roof was instable. The integral support method of intensive surface protecting and high impact toughness was put forward, whose core was the ductility, impact toughness of supporting materials and intensive surface protecting of support components,underground test showed that roadway deformation was safely controlled to 240 mm roof convergence and 130 mm two-sides displacement. Loads of roof cables were fluctuant and loading variation rules of bolts in two sides were different in case of the relation of joints and excavating orientation and coal seam dip.