Objective With the adjustment of the mining face layout in mines, the overburden roof of the mining face for coal pillar recovery is frequently difficult to control when the mining face passes through abandoned roadways.

Methods To address this challenge, this study investigated the coal pillar mining face outside the No.2 panel in the Zhaogu No.2 Coal Mine in Henan Province, which passes through abandoned roadways. Using methods like theoretical analysis, numerical simulation, and in-situ tests, this study examined the composite structure of the mining face and the broken overburden of abandoned roadways, followed by simulation of the full-cycle evolutionary patterns of the stress and displacement of the mining face roof under different support strengths. Finally, it analyzed the mine pressure behavior on the mining face and proposed corresponding control technology.

Results and Conclusions  The results indicate that the breaking forms of the main roof significantly influenced the mine pressure behavior. The breaking of its key blocks might occur above the coal pillar, abandoned roadway, or solid coal. The mechanical mechanisms underlying the advance breaking of the main roof were explored using the established mechanical models of the mining face passing through an abandoned roadway. The main roof was found to be supported by the support system consisting of the abandoned roadway, coal pillar, and mining face, which formed a stable bearing structure in the form of a masonry beam. The critical support strength of the abandoned roadway in the case of the sliding instability of the main roof was determined at 4.6 MPa. The numerical simulation results indicate that the superimposed effects of the advance support pressure of the mining face and the stress concentration in the abandoned roadway significantly affected the coal pillar. As the mining face advanced to 5 m away from the abandoned roadway, the coal pillar experienced instability failure, and the main roof was prone to undergo advance breaking. When the mining face passed through the abandoned roadway, the advance support pressure of the coal pillar shifted from the bimodal to unimodal distribution. The roof stress exhibited varying distribution characteristics under different support strengths, and it was discovered that the support strength of 4.5 MPa of the abandoned roadway could prevent the advance breaking of the main roof. For the coal pillar mining face outside the No.2 panel in the study area, cable anchors were employed as the reinforced support of the abandoned roadway roofs. Consequently, when the mining face passed through the abandoned roadways, the working resistance of hydraulic supports fell within the safe range in the study area, avoiding accidents such as roof collapse and support crushing. This study addressed the technical challenges faced when the coal pillar mining face outside the No.2 panel passed through abandoned roadways, providing a reference for similar mining face.