Study on law of full-period mine pressure behavior of entry retaining method of self-contained entry without coal pillar

In order to stably control the gob-side entry under the condition of non-coal pillar self-contained entry mining,taking the No.S12012 working face of Ningtiaota Coal Mine as the engineering background,and adopting the research method of field measurement,the stress distribution of surrounding rock and roof deformation characteristics of the reused entry during the roadway formed process and the reused process were studied through field measurements.The results show that during entry retention period,the evolution process of entry deformation and roof support pressure can be divided into four stages:initial stable period,severe deformation period,slow transition period,and compaction stable period.The initial stable period is about 0～30 m in front of the working face,the deformation of the roadway is small,and the structural force increase is not obvious; the severe deformation period is about 30～150 m in front of the working face,and the deformation of the roadway increases rapidly,and the stress of the supporting structure in the roadway increases significantly; the range from about 150～200 m in front of the working face is a slow transition period,the deformation of the roadway and the force of the supporting structure in the roadway gradually stabilizes; about 200 m away from the working face is the stable compaction period,the entry deformation remains stable.The force of the supporting structure will no longer change significantly.During the reuse period of the remaining entry,the evolution process of entry deformation and roof support support pressure can be divided into three stages:the stage of stable mine pressure,the stage of gradual change of mine pressure,and the stage of intense mine pressure.The mine pressure stability stage is about 90 m behind the working face,the deformation of the entry is generally small,and the force of the advanced temporary support does not increase significantly; the mine pressure gradual change stage is about 25～90 m behind the working face,and the entry deformation increases at a slower rate,and the force of the advance temporary support gradually increases; the severe mine pressure is in a stage of about 0～25 m behind the working face,the entry deformation and the leading temporary support both increase dramatically.The research results can provide a reference for researchers and field engineering technicians when engaging in support work of reused entry.