Floor deformation control for roof cutting and pressure relief in gob-side entry retaining of deep buried mines

Currently, research and practice on roadway floor heave mainly explore the deformation mechanism and control technology of roadway floor. The mechanical analysis of floor before and after roof cutting and pressure relief in gob-side entry retaining is not comprehensive. In order to solve the above problem, mechanical models of the surrounding rock and floor of the roadway before and after roof cutting are constructed based on the features of coal partition failure. The effects of solid coal, roadway support, and goaf on the floor are analyzed. The analytical solutions for the floor heave of the roadway before and after roof cutting are obtained. The conclusion is drawn that the elastic-plastic zone of the coal wall beside the roadway, the support structure of the roadway, and the load on the floor of the subsidence zone jointly affect the magnitude of the roadway floor heave. Numerical simulation is used to verify the features of rock mass failure, stress distribution, and changes in floor heave in gob-side entry retaining before and after roof cutting and pressure relief. The results show that roof cutting and pressure relief technology can effectively reduce the damage area on the solid coal side and top of the roadway, and maintain the stability of the roadway rock mass structure. The maximum stress of the roadway floor, the resistance of the roadway side support, and the amount of roadway floor heave all decrease, with an average decrease of 25.78%, 56.14%, and 54.07%, respectively. The on-site application results show that the amount of floor heave of thick hard top in gob-side entry retaining is reduced from 709.345 1 mm to 320.965 8 mm. The roof cutting and pressure relief technology can optimize the stress structure of the surrounding rock of the roadway, suppress the floor heave of the roadway, and effectively improve the floor damage.