Quantifying the benefit of cable bolts as supplementary support in coal mines using the strength reduction method.
47th US Rock Mechanics/Geomechanics Symposium, June 23-26, 2013, San Francisco, California. Alexandria, VA: American Rock Mechanics Association, paper no. ARMA-2013-143, 2013 Jun; 1:426-437
The National Institute for Occupational Safety and Health has recently implemented the strength reduction method to evaluate coal mine entry stability in FLAC3D. The method can evaluate the performance of a support system and calculate a stability factor for the entry. For this paper, two studies were analyzed to quantify the impact that cable bolts have on the stability of the entry. The first study investigated the impact of replacing fully grouted bolts with cable bolts for a variety of mining conditions. The strength reduction method was useful for quantifying the additional stability provided by the cable bolts for the mining conditions evaluated. The results were validated with case histories from the Analysis of Roof Bolt Systems (ARBS) database. The second study investigated the benefit of using an angled cable bolt with a steel strap. It was found that with a strap, the cable bolts are better utilized to provide stability. The study also found that the capacity of the cable bolt was not sufficient to provide adequate roof support when used with thicker roof straps. The strength reduction method was useful in quantifying the effectiveness of the cable bolts and determining the weakest link in the support system.
Mining-industry; Coal-mining; Rock-mechanics; Rock-falls; Cables; Mining-equipment; Structural-analysis; Ground-control; Ground-stability; Equipment-reliability; Quantitative-analysis; Environmental-control-equipment
M. M. Murphy, Office of Mine Safety and Health Research, National Institute for Occupational Safety and Health, Pittsburgh, PA, USA
47th US Rock Mechanics/Geomechanics Symposium, June 23-26, 2013, San Francisco, California