Research on the support of roadways with different roof cutting angles in gob-side entry retaining

Gob-side entry retaining is a coal no-pillar mining technology, which can recover coal pillar resources and reduce the quantity, and cost of roadway excavation. However, due to the breaking slewing and sinking movement of the roof of the overlying rock layer, the surrounding rock of the retained roadway will produce large deformation. In order to effectively reduce the stress transfer from the overlying rock layer, the method of cutting off the immediate roof and main roof can be used. This paper proposes a combination support composed of single pillar, π-type beam, articulated roof beam and iron shoe, and analyzes the roof support structure of the combination support for gob-side entry retaining, the mechanism of cutting off the roof, and the synergistic bearing characteristics of gangue rib support. Comprehensive numerical simulation analysis and engineering practice results show that: roadway side of gob-side entry retaining is composed of combined support and gangue rib, they jointly bear the roof pressure, the formation of synergistic bearing structure. The range of plastic zone of surrounding rock for gob-side entry retaining decreases with the reduction of cutting angle. In the field operation, the damage rate of the combination support is low, and the deformation of the surrounding rock for gob-side entry retaining is small, so the effect of surrounding rock control is remarkable.