Deformation mechanism and control technology of large section gateway with top coal in coal mine

In order to solve the support problem of large section gateway with top coal in coal mine, the 7105 working face haulage gateway in Wangzhuang coal mine was taken as engineering example, large section top-coal roadway plastic zone form, displacement and stress evolution law of surrounding rock when naked entry equilibrated conditions were analyzed by using numerical simulation.Based on platts' natural equilibrium arch theory, the top-coal roof of large section roadway with stable coal-walls caving arch mechanical model was established, and layered caving arch height was obtained by mathematical calculation, using the roadway sides plastic zone mechanical model was used to work out the plastic zone width of the top-coal roadway sides. And combined with numerical simulation method, the rock bolt, cable combined support reasonable supporting parameters and support schemes were designed and applied to practical engineering.The results showed that a plastic zone looks like "frog" formed in surrounding rock, the regularly dome-shaped tensile failure zone was in conformity with the platts' arch effect of roadway roof and the top-coal serious bed separation leading to the caving arch height larger than top-coal thickness;Under such conditions, two sides plastic zone was smaller and the sides were relatively stable;As the thick top coal exists, the deformation characteristic of large section top-coal roadway was roof as the biggest, followed by sides and floor.Field monitoring results proved that top-coal roof of large section roadway with stable coal-walls caving arch mechanical model and roadway sides plastic zone mechanical model, combined with numerical simulation comparison the roadway bolt supporting parameters and support schemes determined, can effectively control the deformation of surrounding rock and keep the stability of roadway.