Improving Coal Mine Roof Stability by Pillar Softening.
Maxwell-B; Zink-G; Wang-F
NTIS: PB 276 474 Available for Reference At Bureau Libraries :105 pages
The deformation modulus of coal mine pillars theoretically can be reduced by drilling holes in advance of the mining face. This reduction of modulus along the edge of the pillar has the effect of decreasing the stress concentration in the roof; control of roof caving is thereby predicted. Initial field work indicated that a high horizontal stress field existed at the field test site. Subsequent field work was undertaken to confirm this stress field and to attempt to relieve the horizontal stress in the immediate roof. A method of softening pillars in conjunction with normal mining activity was developed. Significant stress reduction caused by pillar softening was indicated, but the effect of this reduction on roof stability was not established. The vertical roof slots relieved the horizontal stress in the immediate roof very effectively, and observations of roof conditions indicated that the slots definitely improved roof stability.
CP; Final Contract Report;
NTIS Accession No.
NTIS: PB 276 474 Available for Reference At Bureau Libraries
Colorado School of Mines