短语词组短语rock blasting in cut 路堑石方爆破blasting cut out height 切口高度blasting cut length 切口长度position of blasting cut 切口位置blasting cut method 掏槽方式height of blasting cut 爆破切口高度blasting cut height 爆破缺口高度blasting cut out 爆破切口 返回 blasting cut