Analysis of Pressure Relief Effect of Coal Seam Slot Cutting by Diamond Beaded Wire Saw

Deep underground coal mines are severely threatened by dynamic coal rock disasters such as mine pressure bumps and coal and gas outbursts, and coal seam pressure relief technology is widely recognized as the key measure for mitigating these hazards. To investigate the pressure relief effect of coal seam slot cutting using a diamond beaded wire saw, a combined strategy integrating physical similarity simulation and numerical simulation was applied. The stress distribution characteristics of the coal and rock mass during the wire saw cutting procedure were evaluated, and the influence of beaded wire saw diameter on pressure relief efficiency was further examined. (1) Wire saw cutting can substantially decrease the vertical stress within the coal seam; the average pressure relief rate above the slot can reach as high as 61.70%, and the pressure relief effect is clearly stronger than that below the slot. (2) After slot cutting along the roadway, the fully pressure-relieved zone displays an annular spatial pattern; the pressure relief effect at both ends of the slot and around the roadway is particularly evident, whereas the pressure relief degree in the middle part is comparatively low because of the closure effect. (3) Slot closure causes notable changes in the pressure relief state. Before closure, the pressure relief effect above the slot remains satisfactory; after closure, stress recovery appears in the middle part, but the overall pressure relief rate still stays above 10%, and the pressure relief rate at both ends of the slot and near the roadway exceeds 50%, with the fully pressure-relieved zone still maintaining an annular distribution. (4) A positive correlation exists between the wire saw diameter and the height of the fully pressure-relieved zone. For every 0.5 cm increase in diameter, the height of the fully pressure-relieved zone rises by an average of 0.6 m. When the wire saw diameter reaches 3 cm, the full-thickness and adequate pressure relief of a 3 m thick coal seam can be realized.