Study On Stability Prediction Of Mined-out-area In Shallow Close Distance Seams

The mined-out-area floor of shallow-contiguous seams have a large impact on face behindits and constraints safe mining.The study aims at the stability prediction of mined-out-area in the conditions of shallowclose distance seams of1402working face at Shaanxi Fengjiata Mine, be in the specialcondition of shallow-contiguous seams, based on the field survey, physical simulationexperiment, numerical calculation and in-situ monitoring, study and forecast its safe andefficient mining. Results have shown that the roof first pressure step distance of about65.0m,cycle pressure step distance of about15.0m; strata above the coal pillar did not happenabscission, but between the coal pillar, strata generate abscission and the maximum height ofabout1.5m; numerical calculation results show that the fractured zone in the range of50.0-75.0m, the rock of near the protection coal pillar formation stress concentration, coalpillar surrounded by a plastic zone, the surface formation a unsymmetrical sink basin aftermining; radar showed that with top coal about1.2m-1.5m vertical range and1.5m-8.6m roofhave been destroyed cause by underground pressure redistribution and tunneling; cause theoriginal designing of roadways support is unreasonable, through redesigned, the stability hasbeen significantly improved than before.The study can been used at fully mechanized coal face mining in similar burial conditions.