Test of Inclined Roof Bolts & Analysis of Their Effectiveness in Roof Control in Coal Mines.
For Reference Only At Bureau Libraries :139 pages
A comparison was made to determine the relative effectiveness of roof bolts installed at an angle over the rib with that of bolts installed vertically at the side. During the investigation, 235 bolts were installed (45 inclined and 190 vertical) in two adjacent intersections. Of these 235 bolts, 30 were installed with load cells and 38 were tested for anchor capabilities. In addition, the deformation of the opening was measured by convergence meter on nine lines throughout the two test areas. A borescope and photoelastic gages were utilized to obtain information on the roof action beyond the surface. Theoretical analyses indicated that inclined bolts may provide slightly more support than vertical bolts. However, the results of the study show no significant difference between the support capabilities of the two systems. The information gathered does supply supplementary information on the mechanics of roof support systems and the general acceptability of field instrumentation methods.
CP; Final Contract Report;
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Foundation Sciences, Inc.