Study on failure mechanism of withdrawal channel's surrounding rock during last mining period

doi:10.16265/j.cnki.issn1003-3033.2022.02.022

Abstract

Abstract:

In order to make the working face withdrawal safe and efficient, the stress distribution and failure characteristics of withdrawal channel's surrounding rock in fully-mechanized area during last mining period were studies through theoretical analysis and field observation. Then, failure mechanism and method for roof surrounding rock control by supporting force of cog timbering were proposed, and calculation method of minimum initial support force of cog timbering was obtained. The results show that concentrated stress of the withdrawal channel's surrounding rock is gradually superimposed with the bearing pressure in front of working face, which leads to the gradual failure of remaining coal pillar from both sides to the middle. When the failure areas on both sides are connected, the direct top span above coal pillar is increased by 2 times, and the load is large. When the stress and span meet the instability conditions of direct roof, the latter is damaged before working face is cut through, thus leading to roof fall before penetration. Adjusting the initial support force of cog timbering can reduce superimposed stress value of coal pillar at the side of withdrawal channel, corresponding coal pillar width when remaining coal pillar loses stability and the span of direct roof, thus avoiding shear failure and ensuring smooth withdrawal.

Key words: equipment withdrawal channel, failure mechanism, supporting force of chock support, end mining period, superimposed stress

HE Yanjun, SONG Yaxin, SHI Zhanshan, LI Junqi, CHEN Kai, LI Zhiping. Study on failure mechanism of withdrawal channel's surrounding rock during last mining period[J]. China Safety Science Journal, 2022, 32(2): 158-166.

Figures/Tables 12

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