When advancing and uncovering coal in roadway, better construction method is vibration shot, metal framework, borehole bleed-off and hydraulic hole, of which vibration shot is principal.
井巷掘进揭煤时,较好的施工方法是震动放炮,金属骨架,钻孔排放和水力冲孔,尤以震动放炮为主。
Bleed photos off the edge of the page.
把照片从页面边缘上撕下来。
Up to 20 percent of the top airflow should bleed off down the sidewalls.
高达20%的顶部气流应由侧壁向下流动。
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