Numerical modeling of mine backfilling associated with production enhancement at the barapukuria coalmine in Bangladesh

The present article deals with the finite element (FE) method numerical simulation of longwall mine excavation associated with magnitudes and distribution contours of major principal stress (s1), minor principal stress (s3), absolute verthideical displacement, and strength factor that are essential for the backfill study of the Barapukuria coalmine in northwest Bangladesh. Backfill refers to any material that is placed into voids mined underground. Consideration of a suitable backfill material along mine voids is a common technique in coalmines for the control of ground pressure; manage of deformation of surrounding rock strata of a mine panel, and prevention of the ground movement and fracturing of overburden strata. Four stages of calculations have been considered in the present modeling. The magnitudes and distribution contours of major principal stress (s1) imply that the allowable compressive strength of backfill material for the Barapukuria underground coalmine would be ranged between 0.8 MPa to 1.3 MPa. The absolute vertical displacement value was ranging from 0.024 m to 0.028 m at the immediate roof before backfilling. Strength factor with variable results were obtained in all stages of simulation. After extraction of coal, the strength factor at the immediate roof associated with surrounding of the excavation zone was ranging from 0.43 to 0.86. However, subsequent to backfilling, strength factor was increased to 1.71 within the excavation area, which indicates a reasonable factor of safety to prevent ground movement. Finally, it is suggested to think about backfill technology associated with longwall mining at the Barapukuria coalmine that would increase production rate and mine safety.