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TABLE OF CONTENTS <br />DEFINITIONOF SYMBOLS........................................................................................................................Iv <br />DEFINITIONOF TERMS...............................................................................................................................v <br />1.0 <br />INTRODUCTION...........................................................................................................................................1 <br />2.0 <br />MINING METHOD........................................................................................................................................3 <br />3.0 <br />FACTORS INFLUENCING SUBSIDENCE.................................................................................................5 <br />4.0 <br />FIELD RECOGNITION OF SUBSIDENCE AND NON -SUBSIDENCE FEATURES ABOVE THE <br />WESTELK <br />MINE......................................................................................................................................................6 <br />4.1 <br />SUBSIDENCE CRACKS AND COMPRESSION FEATURES........................................................................................6 <br />4.2 <br />CONSTRUCTION CRACKS....................................................................................................................................7 <br />4.3 <br />DESICCATION CRACKS.......................................................................................................................................7 <br />4.4 <br />PSEUDO SUBSIDENCE FEATURES (GRAVITY -INDUCED TENSION CRACKS).........................................................7 <br />5.0 <br />SUBSIDENCE PREDICTION BASED ON LONGWALL MINING AT WEST ELK MINE.................9 <br />5.1 <br />CAVED ZONE......................................................................................................................................................9 <br />5.2 <br />FRACTURED ZONE..............................................................................................................................................9 <br />5.3 <br />CONTINUOUS DEFORMATION ZONE AND NEAR SURFACE ZONE.......................................................................11 <br />5.3.1 <br />Vertical Displacement, Tilt, and Horizontal Strain.................................................................................12 <br />5.3.2 <br />Maximum Projected Depths of Surface Cracks.......................................................................................19 <br />5.4 <br />ANGLE OF DRAW..............................................................................................................................................20 <br />5.5 <br />BREAK ANGLE..................................................................................................................................................20 <br />5.6 <br />ANGLE OF MAJOR INFLUENCE..........................................................................................................................21 <br />5.7 <br />RELATION BETWEEN DYNAMIC AND FINAL SUBSIDENCE DEFORMATIONS.......................................................22 <br />5.8 <br />CRITICAL EXTRACTION WIDTH OF MINING PANELS.........................................................................................22 <br />5.9 <br />RESULTS OF COMPUTER MODELING.................................................................................................................22 <br />6.0 <br />RATE AND DURATION OF SUBSIDENCE.............................................................................................24 <br />7.0 <br />EFFECTS OF TOPOGRAPHY AND STRUCTURE ON SUBSIDENCE PROCESSES .......................25 <br />7.1 <br />EFFECTS OF TOPOGRAPHY ON SUBSIDENCE CRACKS........................................................................................25 <br />7.2 <br />EFFECTS OF RUGGED TOPOGRAPHY ON SUBSIDENCE AND MINE STRESSES......................................................25 <br />8.0 <br />FRACTURE -CONTROLLED DRAINAGES.............................................................................................27 <br />9.0 <br />WATER AND METHANE...........................................................................................................................28 <br />9.1 <br />POTENTIAL IMPACT OF WATER ON SUBSIDENCE IN WET MINING AREAS.........................................................28 <br />10.0 <br />POTENTIAL IMPACTS OF SUBSIDENCE AND MINE -INDUCED SEISMIC ACTIVITY ON <br />LANDSLIDESAND ROCKFALLS........................................................................................................................29 <br />10.1 <br />LANDSLIDES.....................................................................................................................................................29 <br />y <br />