【建筑】Filling，填塞【建筑】预先进行长壁开采

mine roof support for longwall advancing

face support (longwall working), wandering

powered frame support for longwall advancing

face support (longwall working)

longwall system【矿】;longwall workings【矿】

filling longwall method【矿】

longwall pillar working【矿】

mine roof suppo瞨t for longwall advancing