heading and bench mining 下向梯段式回采

top heading and bench method 顶导坑及平台法

heading and bench method 台阶掘进法

heading and bench tunneling method 导洞与层阶法

heading-and-bench [矿业] 梯段掘进

Heading-and-bench drilling 台阶钻孔机

inverted heading and bench 上向回采梯段

heading-and-bench blasting 平巷梯段爆破

heading and bench excavation 导洞与台阶开挖