Estimating Low Back Loads of Underground Mine Roof Bolter Operators using Digital Human Simulations

NIOSH researchers conducted a study to evaluate the severity of muscle recruitment and spine loads resulting from performance of the roof bolting cycle in different work postures and mine seam heights. Ten male and two female subjects performed three repetitions of a mine roof bolting in each of seven posture/seam height combinations, while researchers obtained motion data of their actions using a motion capturing system. A database containing forces on L4/L5 spinal joint and on back muscles was generated by processing the captured motions from each subject using UGS PLM Solution Jack software’s task analysis toolkit – lower back analysis. An analysis of variance was performed using the maximum values for spinal forces and moments and estimated muscle forces for ten trunk muscles in the resulting database. Results of this study indicate that the roof bolter operator’s standing posture significantly increases the forward bending moment, compression force and trunk muscle activity more than either kneeling posture. Also the kneeling postures in a 45-inch seam height significantly increases, compared to a 60-inch seam height, the forward bending moment, twisting moment, compression force, and trunk muscle activity for lateral movements and extending the torso. Impact: Mining industry can use this information to reduce loads on the low back through better work postures from redesigning the machine’s workstation and modifying bolting cycle work procedures.