Numerical-modeling-based assessment of the impact of two-end-type cable support on failure characteristics of yield pillars

Abstract

Yield pillars must be designed to bear the abutment load. Therefore, their stability is a major concern in underground coal mines. However, few scholars have investigated the impact of active support on the bearing capacity of coal pillars. In this study, field tests were performed on a 6-m-wide coal pillar in the Tashan coal mine in China to study the deformation and vertical stress distribution in coal pillars strengthened using the two-end-type cable support. Field monitoring indicated that the maximum deformations of two pillar ribs reached 267 and 135 mm. The maximum vertical-stress-concentration factor of the yield pillar increased from 0.88 to 0.97. Furthermore, the effect of the two-end-type cable support on the stability of the yield pillar was studied based on more than 40 numerical models of various pillar width/height (w/h) ratios and two-end-type-cable-based support designs. The peak and residual strengths exhibited an increasing trend for all models as the row spacing decreased; however, the rates of increase decreased with an increase in the w/h ratio. Variations were observed in the sensitivities of peak and residual strengths with respect to the row spacing. This phenomenon was attributed to the differences in support stress distributions caused by different cable axial forces. Finally, the global model results indicated that the bearing capacity of the coal pillar increased as the row spacing decreased, thereby causing a decrease in the peak stress of the bearing system.