Stability mechanism and control technology for fully mechanised caving mining of steeply inclined extra-thick seams with variable angles

Rock deformation and failure mechanisms, overburden bearing structures, and working characteristics of supports at the no. 120210 working face of the Zaoquan coal mine (Shaanxi, China) have been studied using physical simulations, field tests, and theoretical analysis. Overburden rock movement has distinct regional characteristics, with a large caving height (to the main roof layer) in the upper area, and lower caving height (to the lower main roof) in the lower area. Support loading is regional and unbalanced along the inclined direction. The critical layer of overlying strata migrates, and bearing structures formed by breaking the critical layer exhibit cross-layer generalisation along the inclination. The upper region has a cantilever beam structure in the basic roof rock layer; the lower region has an inclined masonry structure with multistage ladders in the breakage basic roof rock layer. Application of a false-inclined working face layout with the tailgate ahead of the headgate and an arc arrangement (radius 28.65 m, arc length 10-20 m) in variable angle areas, and regional control of support working resistance and top-coal caving amounts, control regional failure overburden. Safe and efficient mining was achieved, with monthly production and recovery rates reaching 344,900 t and 85.86%, respectively. The results could expand the scope of fully mechanised top caving mining.
Rock deformation and failure mechanisms, overburden bearing structures, and working characteristics of supports at the no. 120210 working face of the Zaoquan coal mine (Shaanxi, China) have been studied using physical simulations, field tests, and theoretical analysis. Overburden rock movement has distinct regional characteristics, with a large caving height (to the main roof layer) in the upper area, and lower caving height (to the lower main roof) in the lower area. Support loading is regional and unbalanced along the inclined direction. The critical layer of overlying strata migrates, and bearing structures formed by breaking the critical layer exhibit cross-layer generalisation along the inclination. The upper region has a cantilever beam structure in the basic roof rock layer; the lower region has an inclined masonry structure with multistage ladders in the breakage basic roof rock layer. Application of a false-inclined working face layout with the tailgate ahead of the headgate and an arc arrangement (radius 28.65 m, arc length 10-20 m) in variable angle areas, and regional control of support working resistance and top-coal caving amounts, control regional failure overburden. Safe and efficient mining was achieved, with monthly production and recovery rates reaching 344,900 t and 85.86%, respectively. The results could expand the scope of fully mechanised top caving mining.