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Pressure Law of Roof and Supporting Technology of Roadway When Working Face Passing through Abandoned Roadway

Unlike conventional long-wall mining, the roofing activity is more intense when the long-wall face passes through the abandoned roadway. Technically, the coal pillar between the abandoned roadway and the long-wall face will suddenly fail with a certain critical value of its width, leading to the roof breaks in advance and other production-restricted problems because of the support loss, which will be a great threat to underground mining activities. In order to guarantee safe mining conditions, it is a great necessity to uncover how the roof breaks in advance and how to deal with it. From the stability maintaining of the key block perspective, this study looked at research from the 12404–1 long-wall face of Wulanmulun coal mine, China. The critical value of the coal pillar’s width was determined to be about 4.75 m by theoretical analysis, and likely, the appropriate supporting force of the abandoned roadway’s roof is about 1073 kN per meter. In this study, a numerical simulation method was adopted to study the ground pressure when the long-wall face is passing through the abandoned roadway. Correspondingly, a compound supporting technology involving the roof presplit technique, anchor cable supporting, and pumping pillar supporting was proposed for the roof of the abandoned roadway, and it practically worked well.