Analysis on Rockbolt Support Interaction with Roof Dilatancy Above Roadside Backfill Area in Gob-Side Entry Retaining

To overcome the challenge to the roof dilatancy deformation control above roadside backfill area of gob-side entry retaining for confining pressure decreasing, a mechanical model of rockbolt reinforcement to the roof above roadside backfill area was established. The shear strength of the shear sliding zone above roadside backfill area considering rockbolt support was deduced. Factors and effect of rockbolt reinforcement to the shear sliding zone of the roof above roadside backfill area based on the 3107 working face of Xinyuan coal mine were obtained. Moreover, a numerical model was established to analyze rockbolt support for roof dilatancy deformation control. Mechanical results show that the shear strength increment from rockbolt axial force is positively related with rockbolt arrange density and rockbolt pretension while the shear strength increment from rockbolt shear force is positively related with rockbolt diameter, rockbolt arrangement density. Numerical results indicate that rockbolt support improves the confining pressure environment around the gateway excavation and effectively restrains roof dilatancy deformation of lower confining pressure region. Field tests and field monitoring indicated that the gob-side entry retaining in the 3107 working face with a width of 2.0 m roadside backfill body and high-strength rockbolt support for the roof above roadside backfill area could meet the requirement for gas drainage and ventilation when 3107 working face was retreating.