11
fully grouted rib bolts with an anchorage capacity of 1.13
ton/in, contributes to stability. Additionally, the underly-
ing coal seam, 3.2-ft to 4-ft thick and with a compressive
strength of 3,747 psi, provides a solid foundation. The
coal pillar ribs maintain their integrity for at least the first
24 in., evidenced by a minimal horizontal displacement of
about 0.04 in., indicating overall rib stability. Effective roof
caving during pillar retreat has reduced stress transfer, lead-
ing to slight roof convergence (0.1 in.) and minimal front
abutment loads. This results in favorable stability factors of
1.76 during development loading and 1.56 during retreat
loading, further preventing rib brow formation.
STUDY LIMITATIONS
During the site preparation tour, we observed that the study
mine has the potential for rib brow formation, particularly
near pillar corners. However, no rib brows formed in the
instrumented pillar, making the collected data specific to
this site. Although the monitoring data and visual obser-
vations provided insights into the loading mechanisms
affecting the instrumented pillar, these findings are highly
site-specific and may have limited applicability to other
mining sites, especially those with different geological or
geometric characteristics. Furthermore, this study assumed
no multi-seam interactions based on ACPS calculations
and did not attempt to correlate field observations or moni-
toring results with potential multi-seam effects.
ACKNOWLEDGMENT
The authors would like to express their gratitude to Mr.
Todd Minoski for his work in preparing the data collection
system, Mr. Mark Mazzella for setting up the instruments,
and Mr. James Addis for his invaluable assistance with field
instrumentation.
DISCLAIMER
The findings and conclusions in this study are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health (NIOSH), Centers for Disease Control and
Prevention (CDC). Mention of any company or product
does not constitute endorsement by NIOSH.
The authors from the Missouri University of Science
and Technology acknowledge the financial support from
the Alpha Foundation for the Improvement of Mine Safety
and Health, Inc. The views, opinions, and recommenda-
tions expressed herein are solely those of the authors and do
not imply any endorsement by the Alpha Foundation and
its Directors and staff.
REFERENCES
[1] Colwell, M. (2006). A Study of the Mechanics of
Coal Mine Rib Deformation and Rib Support as a
Basis for Engineering Design. Ph.D. Thesis. University
of Queensland. Queensland, Australia.
[2] Esterhuizen, G. S., Gearhart, D. F., and Tulu, I.
B. (2018). Analysis of monitored ground sup-
port and rock mass response in a longwall tailgate
entry. International Journal of Mining Science and
Technology, 28(1), 43–51. https://doi.org/10.1016
/j.ijmst.2017.12.013.
[3] Geokon, Inc. (2024). “Model 3200 Borehole
Pressure Cell Instruction Manual,” https://www
.geokon.com/content/manuals/3200/index
.html#t=topics%2Fcover.htm.
[4] Heritage, Y. (2019). Mechanics of rib deformation
– Observations and monitoring in Australian coal
mines. International Journal of Mining Science and
Technology, 29(1), 119–129.
[5] Jones, T., Mohamed, K., and Klemetti, T. (2014).
“Investigating the Contributing Factors to Rib
Fatalities through Historical Analysis.” In Proceedings
of the 33rd International Conference on Ground Control
in Mining, Morgantown, pp. 113–122.
[6] Klemetti, T. M., Van Dyke, M. A., and Tulu, I. B.
(2018). Deep cover bleeder entry performance and
support loading: A case study. International Journal of
Mining Science and Technology, 28(1), 85–93. https://
doi.org/10.1016/j.ijmst.2017.11.012.
[7] Klemetti, T. M., Van Dyke, M. A., Compton, C.
S., Tulu, I. B., Tuncay, D., and Wickline, J. (2019).
Longwall gateroad yield pillar response and model
verification – A case study. 53rd U.S. Rock Mechanics/
Geomechanics Symposium.
[8] Klemetti, T. M., Van Dyke, M. A., Evanek, N.,
Compton, C. C., and Tulu, I. B. (2021). Insights
into the Relationships Among the Roof, Rib, Floor,
and Pillars of Underground Coal Mines. Mining,
Metallurgy and Exploration, 38(1), 531–538. https://
doi.org/10.1007/s42461-020-00313-7.
[9] Mark, C., Chase, F. E. (1997). Analysis of Retreat
Mining Pillar Stability. NIOSH IC 9446. In:
Proceedings of the NIOSH Technology Transfer Seminar.
Pittsburgh, PA: USBM 1997. p. 17–34.
[10] Mark C., Agioutantis, Z. (2019). Analysis of coal pil-
lar stability (ACPS): A new generation of pillar design
software. International Journal of Mining Science and
Technology, Volume 29, Issue 1, January 2019, Pages
87–91.
fully grouted rib bolts with an anchorage capacity of 1.13
ton/in, contributes to stability. Additionally, the underly-
ing coal seam, 3.2-ft to 4-ft thick and with a compressive
strength of 3,747 psi, provides a solid foundation. The
coal pillar ribs maintain their integrity for at least the first
24 in., evidenced by a minimal horizontal displacement of
about 0.04 in., indicating overall rib stability. Effective roof
caving during pillar retreat has reduced stress transfer, lead-
ing to slight roof convergence (0.1 in.) and minimal front
abutment loads. This results in favorable stability factors of
1.76 during development loading and 1.56 during retreat
loading, further preventing rib brow formation.
STUDY LIMITATIONS
During the site preparation tour, we observed that the study
mine has the potential for rib brow formation, particularly
near pillar corners. However, no rib brows formed in the
instrumented pillar, making the collected data specific to
this site. Although the monitoring data and visual obser-
vations provided insights into the loading mechanisms
affecting the instrumented pillar, these findings are highly
site-specific and may have limited applicability to other
mining sites, especially those with different geological or
geometric characteristics. Furthermore, this study assumed
no multi-seam interactions based on ACPS calculations
and did not attempt to correlate field observations or moni-
toring results with potential multi-seam effects.
ACKNOWLEDGMENT
The authors would like to express their gratitude to Mr.
Todd Minoski for his work in preparing the data collection
system, Mr. Mark Mazzella for setting up the instruments,
and Mr. James Addis for his invaluable assistance with field
instrumentation.
DISCLAIMER
The findings and conclusions in this study are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health (NIOSH), Centers for Disease Control and
Prevention (CDC). Mention of any company or product
does not constitute endorsement by NIOSH.
The authors from the Missouri University of Science
and Technology acknowledge the financial support from
the Alpha Foundation for the Improvement of Mine Safety
and Health, Inc. The views, opinions, and recommenda-
tions expressed herein are solely those of the authors and do
not imply any endorsement by the Alpha Foundation and
its Directors and staff.
REFERENCES
[1] Colwell, M. (2006). A Study of the Mechanics of
Coal Mine Rib Deformation and Rib Support as a
Basis for Engineering Design. Ph.D. Thesis. University
of Queensland. Queensland, Australia.
[2] Esterhuizen, G. S., Gearhart, D. F., and Tulu, I.
B. (2018). Analysis of monitored ground sup-
port and rock mass response in a longwall tailgate
entry. International Journal of Mining Science and
Technology, 28(1), 43–51. https://doi.org/10.1016
/j.ijmst.2017.12.013.
[3] Geokon, Inc. (2024). “Model 3200 Borehole
Pressure Cell Instruction Manual,” https://www
.geokon.com/content/manuals/3200/index
.html#t=topics%2Fcover.htm.
[4] Heritage, Y. (2019). Mechanics of rib deformation
– Observations and monitoring in Australian coal
mines. International Journal of Mining Science and
Technology, 29(1), 119–129.
[5] Jones, T., Mohamed, K., and Klemetti, T. (2014).
“Investigating the Contributing Factors to Rib
Fatalities through Historical Analysis.” In Proceedings
of the 33rd International Conference on Ground Control
in Mining, Morgantown, pp. 113–122.
[6] Klemetti, T. M., Van Dyke, M. A., and Tulu, I. B.
(2018). Deep cover bleeder entry performance and
support loading: A case study. International Journal of
Mining Science and Technology, 28(1), 85–93. https://
doi.org/10.1016/j.ijmst.2017.11.012.
[7] Klemetti, T. M., Van Dyke, M. A., Compton, C.
S., Tulu, I. B., Tuncay, D., and Wickline, J. (2019).
Longwall gateroad yield pillar response and model
verification – A case study. 53rd U.S. Rock Mechanics/
Geomechanics Symposium.
[8] Klemetti, T. M., Van Dyke, M. A., Evanek, N.,
Compton, C. C., and Tulu, I. B. (2021). Insights
into the Relationships Among the Roof, Rib, Floor,
and Pillars of Underground Coal Mines. Mining,
Metallurgy and Exploration, 38(1), 531–538. https://
doi.org/10.1007/s42461-020-00313-7.
[9] Mark, C., Chase, F. E. (1997). Analysis of Retreat
Mining Pillar Stability. NIOSH IC 9446. In:
Proceedings of the NIOSH Technology Transfer Seminar.
Pittsburgh, PA: USBM 1997. p. 17–34.
[10] Mark C., Agioutantis, Z. (2019). Analysis of coal pil-
lar stability (ACPS): A new generation of pillar design
software. International Journal of Mining Science and
Technology, Volume 29, Issue 1, January 2019, Pages
87–91.