Mining Project: Underground Stone Mine Pillar Design in Challenging Conditions

Keywords: Pillar design Pillars Stone mining
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Principal Investigator
Start Date 10/1/2016
End Date 9/30/2021
Objective

To build the framework for expanding pillar design criteria in challenging multiple-level, deep, and dipping mining environments by undertaking thorough pillar response investigations in representative conditions at case study mine sites and by developing design criteria for these scenarios.
Topic Area

Research Summary

From 2005 to 2015, fatalities related to ground control in underground stone mines accounted for 50% of the total fatalities. The injury rate had increased significantly from 2013 to 2015. Likewise, the fatality rate in the underground stone sector had increased overall during the past decade. The risks driving these trends were likely to increase as operations mined under deeper cover with steeper dips and more adverse geological conditions.

NIOSH developed and made public the first pillar design software program (S-Pillar) for underground stone mining in 2011, which has been widely accepted and used regularly by mining operations and the Mine Safety and Health Administration (MSHA). The empirically based S-Pillar software was designed to meet the pillar design needs of the majority of the underground stone mine industry, but this software did not address several uniquely challenging environments. Stakeholder discussions had indicated to NIOSH researchers that these environments would likely be encountered more often at future mining operations. Analyzing case histories for the conditions outside the scope of the previous research was necessary to provide a detailed analysis of the hazards associated with these insufficiently studied environments.

This project involved five research aims, summarized as follows.

Research Aim 1. Develop an empirical database of existing limestone operations in multiple levels, deep cover, and dipping seams, and document fundamental pillar design parameters and qualitative performance assessments.

Research Aim 2. Identify study mines and conduct exploratory investigations to determine rock mass characterization, material properties, stress conditions, geologic features, and measured pillar responses at target locations that support a parametric assessment of pillar stability.

Research Aim 3. Identify pillar instability mechanisms occurring in challenging environments, such as multiple levels, deep cover, and dipping seams, and identify differences compared to instability mechanisms in less challenging environments that form the basis of current pillar design guidelines.

Research Aim 4. Develop and calibrate numerical models that replicate pillar responses and failure mechanisms and validate against case study mine observations and measured responses in challenging mine environments.

Research Aim 5. Assess global stability issues and develop pillar design criteria based on case study results that will form the basis for establishing universal design guidelines for stone mining in challenging environments, such as multiple levels, deep cover, and dipping seams.

Research occurred at underground stone mines in Pennsylvania, Ohio, and Tennessee, with seismic, stress, and laser scan data collected and analyzed to help better design underground mines in challenging environments. During the execution of the project, a number of technical papers were published as specific milestones. Results were presented the Annual Underground Stone Seminar, the International Conference on Ground Control in Mining, and the U.S. Rock Mechanics/Geomechanics Symposium throughout the life of the project, ultimately culminating in two journal articles on pillar design criteria in these challenging environments.

Related Publications

Multiple-level Studies
  • Rashed G, Slaker B, Murphy M [2022]. Exploration of limestone pillar stability in multiple-level mining conditions using numerical models. Mining, Metallurgy & Exploration 39(5):1887-1897. https://doi.org/10.1007/s42461-022-00655-4
  • Slaker B, Murphy M, Rashed G, Gangrade V, Van Dyke M, Minoski T, Floyd K [2020]. Monitoring of multiple-level stress interaction at two underground limestone mines. Mining, Metallurgy & Exploration 38:623-633. https://doi.org/10.1007/s42461-020-00345-z
  • Rashed G, Slaker B, Murphy M [2021]. Exploration of limestone pillar stability in multiple-level mining conditions using numerical models. In: Proceedings of the 40th International Conference on Ground Control in Mining.
  • Rashed G, Slaker B [2020]. A study of the interburden stability in multilevel limestone mines. In: Proceedings of the 54th US Rock Mechanics/Geomechanics Symposium, virtual from in Golden, CO, June 28-1-July 1, ARMA 20–1949.
  • Slaker B, Murphy M, Rashed G, Gangrade V, Van Dyke M, Minoski T, Floyd K [2020]. Monitoring of multiple-level stress interaction at two underground limestone mines. In: Proceedings of the SME Annual Meeting, Phoenix, AZ. Society for Mining, Metallurgy, and Exploration, Inc., Preprint 20-079. Feb. 23-26.
Dipping Studies
Pillar Design and Challenging Conditions
  • Evanek N, Slaker B, Iannacchione A, Miller T [2021]. LiDAR mapping of ground damage in a heading re-orientation case study. International Journal of Mining Science and Technology 31(1):67-74. https://doi.org/10.1016/j.ijmst.2020.12.018
  • Evanek N, Iannacchione A, Miller T [2021]. Controlling crosscut damage in response to excessive levels of horizontal stress: Case Study at the Subtropolis Mine, Petersburg, OH. Mining, Metallurgy and Exploration, 38: 645-653. https://doi.org/10.1007/s42461-020-00357-9
  • Iannacchione A, Miller T, Esterhuizen G, Slaker B, Murphy M, Cope N, Thayer S [2020]. Evaluation of stress-control layout at the Subtropolis Mine, Petersburg, Ohio. International Journal of Mining Science and Technology 30(1):77-83. https://doi.org/10.1016/j.ijmst.2019.12.009
  • Esterhuizen G, Tyrna P, Murphy M [2019]. A case study of the collapse of slender pillars affected by through-going discontinuities at a limestone mine in Pennsylvania. Rock Mechanics and Rock Engineering 52(12):4941-4952. https://doi.org/10.1007/s00603-019-01959-6
  • Slaker B, Murphy M, Miller T [2018]. Analysis of extensometer, photogrammetry and laser scanning monitoring techniques for measuring floor heave in an underground limestone mine. Transactions of Society for Mining, Metallurgy, and Exploration, Inc, 344(1):31. https://doi.org/10.19150%2Ftrans.8746
  • Evanek N, Slaker B, Iannacchione A [2020]. LiDAR mapping of ground damage reduction in a heading re-orientation case study. In: Proceedings of the 39th International Conference on Ground Control in Mining (ICGCM), Canonsburg, PA, July 28-30, pp. 134-143.
  • Evanek N, Iannacchione A, Miller T [2020]. Controlling crosscut damage in response to excessive levels of horizontal stress: case study at the Subtropolis Mine, Petersburg, OH. In: Proceedings of the MineXchange 2020 SME Annual Conference & Expo, 23-26 February 2020, Phoenix, AZ.  https://link.springer.com/article/10.1007/s42461-020-00357-9
  • Murphy M, Esterhuizen G, Slaker B [2020]. Addressing stone mine pillar design with the NIOSH S-Pillar Software. In: Proceedings of the SME Annual Meeting, Phoenix, AZ. Society for Mining, Metallurgy, and Exploration, Inc., Preprint 20-025. Feb. 23-26.
  • Iannacchione A, Miller T, Cope N, Esterhuizen G, Slaker B, Murphy M, Thayer S [2019]. Evaluation of stress control layout at the Subtropolis Mine, Petersburg, Ohio. In: Proceedings of the 39th International Conference on Ground Control in Mining (ICGCM), Morgantown, WV, July 23-25, pp. 122-131. 

    https://www.sciencedirect.com/science/article/pii/S2095268619306093

  • Slaker B, Murphy M, Miller T [2017]. Analysis of monitoring techniques to measure floor heave in an underground limestone mine. In: Proceedings of the 2017 SME Annual Meeting, February 19–22, Denver, CO. Englewood, CO: Society for Mining, Metallurgy, and Exploration, Inc. Preprint 17-010.

Related Software

See Also
Page last reviewed: January 13, 2023
Page last updated: January 13, 2023
Content source: National Institute for Occupational Safety and Health, Mining Program