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