Study on manifestation of ground pressure in"first square"return airway of inclined soft coal seam working face
A 15 m section coal pillar test was conducted under the conditions of inclined soft coal seams at the No.11501 working face in the Mengjiayao Coal Mine.After the"first square"of the working face,abnormal deformation occurred within a certain range ahead of the working face in the return airway,often accompanied by unusual sounds.Addressing this issue,the working conditions during the"first square"period of the No.11501 working face was taken as the research background.Using the 3DEC numerical simulation soft-ware,a numerical model of the No.11501 working face was established to analyze the evident patterns of ground pressure before and af-ter the"first square"at the No.11501 return airway,explaining the sources of the unusual sounds within the return airway during the"first square"period.The results showed that the influence range of the advanced support pressure at the No.11501 working face was a-bout 50-70 m.During the weighting period,the deformation rate of the lower,roof,and upper sides of the return airway accelerated sig-nificantly,and non-uniform deformation occured.During the"square"period in the working face,the main cause of the unusual sounds in the return airway was that the goaf has been broken and the roof has been broken again due to the impact of mining.This caused phe-nomena such as the sinking of the lower roof side,bulging deformation of the lower side,inwards collapse of the tray into the coal,and breakage of steel bands in the No.11501 return airway.To address this issue,non-uniform reinforcement support measures were pro-posed for the No.11501 return airway,achieving good application results.The research findings provide a scientific basis for maintaining the return airway in the subsequent mining work of the No.11501 working face and offer a reference for similar mines under inclined soft coal seam conditions.
万方数据
