roof step

This paper introduces the successful experience of over roadway extraction in complex geology that has roof step, face roof collapse with cavity, passing through fault etc.

介绍了135采煤队在顶板台阶下沉、漏顶、压力大、过断层等复杂地质因素影响下，跨巷道高档普采成功回采的经验。

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Take the sand-asphalt cushion displacement of# 1 floating roof tank in Linyi Initial Station as an example, this paper introduces the lifting process of pontoon's center stand, lifting step, calculation of lifting force and method of material selection.

以临邑首站1号浮顶罐罐底板和沥青砂垫层全部更换为例，介绍了浮船中央立柱提升技术的施工工艺、施工步骤及提升力计算和材料选用的方法。

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