Mechanism and countermeasures of abandoned roadway collapse in three-roadway stope mining one side pillar

In order to find out the reason of large area roof cutting and caving in abandoned roadway during the mode of mining one side pillar and three-roadway arrangement of 202 working face in Daning Coal Mine, based on the field observation and theoretical analysis of mine pressure, the mechanical model of the overlying strata in the abandoned roadway is established, and the mechanism and countermeasures of roof cutting and caving are analyzed and practiced. The research results and field practice show that unreasonable support causes the basic roof above the roadway to break in advance, and the sliding of the “long key block” is unstable, which is the root reason of the basic roof cutting and caving. When the back-filling measures are taken and back-filling strength of the abandoned roadway is 1 MPa to 1.2 MPa, it can control the coal wall and roof subsidence effectively and the stress state around the abandoned roadway can be greatly improved to form a situation that is conducive to passing through the abandoned roadway, ensuring the mining succeed.