2021-02-05_PERMIT FILE - C1980007A ‎(5)‎

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 2/5/2021
• Doc Name: SUBSIDENCE EVALUATION
• Section_Exhibit Name: Exhibit 60E Subsidence Evaluation for the South of Divide and Dry Fork Mining Areas
• Media Type: D
• Archive: Yes

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