Numerical Investigation on Factors Affecting the Performance of Roof Bolts for Continuous Miner Working

Optimum support design of roof bolts based on axial load of the bolt plays the major role for effective development of coal seam with continuous miner. Axial load on the roof bolts gives a clear understanding of the behaviour of roof bolts in different working conditions. Therefore, estimation of axial load on the bolts is important for supporting the immediate roof, helps in higher production, productivity and safety. By using the software FLAC 3D, the axial load for different gallery widths and working depths was estimated. From the simulation results, it was observed that for shallow depths of 100 and 200 m, the axial load acting on the bolt is 15% of the bolt capacity at gallery widths of 4 m and 5 m. Whereas for moderate depths 300 m and 400 m, its value is found to be 75% at gallery widths 6 m and 7 m. But, for deeper depths of 500 m and more, its values reaches maximum capacity of roof bolts.

Also, the roof convergence in junction, for moderate and deeper depths is 80 mm to 150 mm, whereas for shallow depths its value is 10–25 mm, at 6 m, 7 m and 8 m gallery widths.