Local instability mechanism and countermeasures for inclined-shaft with water-abundant soft rock

The 1st air return inclined shaft of Qing Shui Ying mine in Ningxia has been seriously damaged locally, roof fall has occurred for many times in large area.Through on-site investigation in falling area to explore the reasons for destruction, and according to the engineering geological conditions of the site, finite difference procedure and physical similarity simulation experiments were used to analyze the local instability mechanism of the roof, it was identified that the effect of localization of water-conducting fractured zone and deformation was the main reason inducing change of effective stress and instability of plastic zone.Aimed at areas with light and serious falling, the joint suport program of"bolt-steel net-steel belt-groutting and no.11 mine-steel shelf beam" was proposed.Engineering results showed that the supporting technology for this type of surrounding rock was effective and economic.