1 / 30

The Ground Response Curve, Pillar Loading and Pillar Failure

The Ground Response Curve, Pillar Loading and Pillar Failure. G.S. (Essie) Esterhuizen Chris Mark Michael Murphy.

sasha
Download Presentation

The Ground Response Curve, Pillar Loading and Pillar Failure

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Ground Response Curve, Pillar Loadingand Pillar Failure G.S. (Essie) Esterhuizen Chris Mark Michael Murphy The findings and conclusions in this presentation are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

  2. Background • Review of retreat pillar mining • Role of overburden response in loading and failure of pillars Gob Gob Gob

  3. Overburden response • Pillar loading • Pillar failure

  4. Overburden response

  5. Overburden response can determine whether pillars fail or not Stiff strong overburden Weak-soft overburden Well developed pressure arch Poorly developed pressure arch

  6. Overburden behavior can be represented by a “ground response curve” Overburden stress 1600 Stress Load transferred to abutments by arching Weak Strong 30% 10% 20% 0 Load transferred to abutments by arching Convergence Load carried by internal supports

  7. Ground response curves can be estimated using realistic numerical models 3500 ft Strong beds 2500 ft Coal bed Extraction panels

  8. Ground response development conditions Ground response recorded at center of panel

  9. Effect of panel width on ground responseDevelopment conditions - Depth 1500 ft - Western US geology 2,000 1,500 1,000 500 0 Overburden stress Stress (psi) Width 80 ft 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Convergence (inches)

  10. Effect of panel width on ground responseDevelopment conditions - Depth 1500 ft - Western US geology 2,000 1,500 1,000 500 0 Overburden stress Stress (psi) Width 150 ft Width 80 ft 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Convergence (inches)

  11. Effect of panel width on ground responseDevelopment conditions - Depth 1500 ft - Western US geology 2,000 1,500 1,000 500 0 Overburden stress Stress (psi) Width 150 ft Width 250 ft Width 80 ft 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Convergence (inches)

  12. Effect of panel width on ground responseDevelopment conditions - Depth 1500 ft - Western US geology 2,000 1,500 1,000 500 0 Overburden stress Stress (psi) Width 500 ft Width 150 ft Width 250 ft Width 80 ft 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Convergence (inches)

  13. Effect of panel width on ground responseDevelopment conditions - Depth 1500 ft - Western US geology 2,000 1,500 1,000 500 0 Overburden stress Stress (psi) Width 1000 ft Width 500 ft Width 150 ft Width 250 ft Width 80 ft 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Convergence (inches)

  14. Ground response at the pillar extraction line Ground response was recorded at center of extraction line Gob Extraction line

  15. Ground response at the pillar extraction line Panel width 500 ft at 1500 ft depth – Western US geology 6,000 4,500 3,000 1,500 0 At extraction line Stress (psi) Stress (MPa) Overburden stress Development conditions 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Convergence (inches) Convergence (m)

  16. Pillar response

  17. Pillar response curves Distributed stress over entire panel

  18. Combined pillar and ground response curvesPillar W:H = 8 Overburden stress

  19. Effect of panel width on pillar loading Pillar W:H = 8 Overburden stress

  20. Effect of panel width on pillar loading Pillar W:H = 8

  21. Effect of panel width on pillar loading Pillar W:H = 6 Overburden stress

  22. Effect of panel width on pillar loading Yield pillar W:H = 3 Overburden stress 80 ft

  23. Pillar loading at the extraction line500 ft wide panel at 1500 ft depth Western US geology Extraction line Development

  24. Pillar loading at the extraction line500 ft wide panel at 1500 ft depth Western US geology Extraction line Development

  25. Pillar loading at the extraction line500 ft wide panel at 1500 ft depth Western US geology Extraction line Development

  26. Pillar loading at the extraction line500 ft wide panel at 1500 ft depth Western US geology Extraction line Development

  27. Pillar failure

  28. Structural failure of pillars 14.0 Structural strength = peak resistance 12.0 10.0 Stress (MPa) 8.0 W:H = 6 6.0 Structural failure 4.0 2.0 0.0 0.0% 2.0% 4.0% 6.0% 8.0% 10.0% Convergence

  29. Functional failure of pillars Functional failure Convergence

  30. Conclusions • Ground response and pressure arch formation are affected by: • Rock stiffness and strength • Panel width • Ground response affects: • Pillar loading • Ultimate success/failure of pillars • Ground response evaluation has demonstrated: • Importance of panel width on success of pillar mining • Structural failure of pillars does not necessarily imply functional failure • Functional failure appears to be related to ultimate pillar strain (%conv)

More Related