Research on variation law of secondary stress on working face of Guotun Coal Mine

For deformation and failure situation of roadway on 1304 working face of Guotun Coal Mine, the secondary stress of the working face was measured. Three monitoring drills were constructed at one point of the roadway on 1304 working face, and four HI sensors were set in the boreholes at 150 m away from the working face, which were used to monitor the secondary stress variation generated by rock mass at different positions influenced by mining. The field test results show that peak position of advancing abutment pressure is at about 6.9 m ahead of the working face, and stress concentration factor is about 2. In order to avoid the peak value of the advancing abutment pressure, the size of small coal pillar should be less than 6.9 m. Vertical stress of the laneway’s side is higher, which is 56.7 MPa. Therefore, the roadway should be timely supported to improve carrying capacity of the small coal pillar.