2011-02-14_PERMIT FILE - C1980007A ‎(3)‎

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 2/14/2011
• 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

n
U
TABLE OF CONTENTS
DEFINITIONOF SYMBOLS ................................................................................... ............................... iv
DEFINITIONOF TERMS ......................................................................................... ............................... v
1.0 INTRODUCTION ....................................................................................................... ..............................
2.0 MINING METHOD .................................................................................................... ..............................
3.0 FACTORS INFLUENCING SUBSIDENCE .............................................................. ..............................
4.0 FIELD RECOGNITION OF SUBSIDENCE AND NON - SUBSIDENCE FEATURES IN THE WEST
ELKMINING AREA ............................................................................................................ ............................... 5
4.1 SUBSIDENCE CRACKS AND COMPRESSION FEATURES .......................................................... ..............................
4.2 CONSTRUCTION CRACKS ................................................................................................... ............................... 6
4.3 DESICCATION CRACKS ...................................................................................................... ............................... 6
4.4 PSEUDO SUBSIDENCE FEATURES GRAVITY- INDUCED TENSION CRACKS) ............................ ............................... 6
5.0 SUBSIDENCE PREDICTION BASED ON LONGWALL MINING AT WEST ELK MINE ............... 8
5 .1 CAVED ZONE ................................................................................................................ ............................... 8
5.2 FRACTURED ZONE ........................................................................................................ ............................... 8
5.3 CONTINUOUS DEFORMATION ZONE AND NEAR SURFACE ZONE .................................... ............................... 10
5.3.1 Vertical and Horizontal Displacement, Tilt, and Horizontal Strain ...................... ............................... 10
5.3.2 Maximum Projected Depths of Surface Cracks .................................................... ............................... 14
5.4 ANGLE OF DRAW ........................................................................................................ ............................... 16
5.5 BREAK ANGLE ............................................................................................................ ............................... 16
5.6 ANGLE OF MAJOR INFLUENCE ..................................................................................... ............................... 17
5.7 RELATION BETWEEN DYNAMIC AND FINAL SUBSIDENCE DEFORMATIONS .................... ............................... 17
5.8 CRITICAL EXTRACTION WIDTH OF MINING PANELS ..................................................... ............................... 17
5.9 RESULTS OF COMPUTER MODELING ............................................................................ ............................... 18
6.0 RATE AND DURATION OF SUBSIDENCE ........................................................... .............................19
7.0 EFFECTS OF TOPOGRAPHY AND STRUCTURE ON SUBSIDENCE PROCESSES ..................... 20
7.1 EFFECTS OF TOPOGRAPHY ON SUBSIDENCE CRACKS .................................................... ............................... 20
7.2 EFFECTS OF RUGGED TOPOGRAPHY ON SUBSIDENCE AND MINE STRESSES .................... ............................... 20
8.0 FRACTURE- CONTROLLED DRAINAGES ......................................................... ............................... 22
9.0 WATER AND METHANE ...................................................................................... ............................... 23
i