Evaluation of the Effect of Coal Seam Dip on Stress Distribution and Displacement around the Mechanized Longwall Panel

Abstract

The main purpose of this research is to evaluate the effect of coal seam dip on the front abutment and side abutment stresses distribution around the longwall panels by FLAC3D software. For this purpose numerical modeling of five longwall panels in coal seam with dip angle of 0, 12, 22, 32 and 42 degree have been done. The results of numerical modeling have been shown that in all models, peak value of front abutment stress was found to act at a distance about 1–3 m in front of the panel face and the difference between this stresses in front of the working face is about 9.7 MPa. In this distance, the peak vertical stress is in the order of approximately 4–5 times the in-situ stress and then gradually decreases toward the initial field stress. Moreover numerical modeling results have been shown that increasing coal seam dip has no significant effect on the peak value of side abutment stress at the edge of pillar, but the side abutment stress concentration is nearer to the edge of pillar. At coal seam dip of zero and 12 degrees, maximum vertical stress occurs at a distance of 5.4 m from the pillar edge, whereas at the coal seam dip of 42 degrees, this stress occurs within 3 m of the pillar edge. However, increasing the dip of coal seam caused to increase entry roof displacement. The results are in good agreement with field observation.