Coal Pillar Stability

In the 1990’s, the Analysis of Longwall Pillar Stability (ALPS) inaugurated a new era in coal pillar design. ALPS was the first empirical pillar design technique to consider the abutment loads that arise from full extraction, and the first to be calibrated using an extensive database of mining case histories. ALPS was followed by the Analysis of Retreat Mining Stability (ARMPS) and the Analysis of Multiple Seam Stability (AMSS). These methods incorporated other innovations including the Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar strength formula, and the pressure arch loading model. They also built upon ever larger case history databases and employed more sophisticated statistical methods.

Today, these empirical methods are used in nearly every underground coal mine in the US. However, the piecemeal manner in which these methods have evolved resulted in some weaknesses. For example, in certain situations, it may not be obvious which program is the best to use. Other times the results from the different programs are not entirely consistent with each other. The programs have also not been updated for several years, and some changes were necessary to keep pace with new developments in mining practice.

The Analysis of Coal Pillar Stability (ACPS) now integrates all three of the older software packages into a single pillar design framework. ACPS also incorporates the latest research findings in the field of pillar design, including an expanded multiple seam case history data base and a new method to evaluate room and pillar panels containing multiple rows of pillars left in place during pillar recovery. ACPS also includes updated guidance and warnings for users, and features an upgraded help file and graphics.

Below is a timeline of the initial release and updates as well as links to download the program and help information.

  • ACPS was officially released in December 2018.
  • Aug 06, 2019 update (v1.0.77): Added numerous example files as well as help associated with each example.
  • Aug 14, 2019 update (v1.0.78): Corrected a couple of bugs in the input data reporting module.
  • Sep 21, 2019 update (v1.0.79): Corrected a couple of bugs in the metric version of the program. Updated a couple of pdf files in the examples.
  • Feb 13, 2020 update (v1.0.80): Updated to allow up to 6 entries in longwall gateroad analysis.
  • March 14, 2020 update (v1.0.81): Corrected a bug related to the warning messages in the multiple seam analysis.
  • May 07, 2020 update (v1.0.82): Corrected CMRR output for manual settings and a formatting issue with the help file.
  • July 01, 2020 update (v1.0.83): Corrected issues with not correctly saving the manual CMRR setting options. Updated the help file with the recommended procedure for estimating depth of cover over longwall gates under mountainous terrain.
  • July 27, 2020 update (v1.0.84): Corrected reporting of LFBAR.
  • Sept 19, 2020 update (v1.0.85): Updated example files and documentation.
  • Nov 3, 2020 update (v1.0.86): Updated pillar bearing capacity plot and clarified leave row widths in output.
  • Jan 11, 2021 update (v1.0.87): Updated pillar bearing capacity output in LW gates to tons/ft. Added new multiple seam paper in documentation.
  • March 06, 2021 update (v1.0.88): Updated multiple seam paper in documentation.
  • April 02, 2021 update (v1.0.89): Updated load calculation for barrier pillars. Updated installer.
  • April 30, 2021 update (v1.0.90): Updated help file and resource files with information on massive gob collapse.
  • May 19, 2021 update (v1.1.01): Updated resource files with ARMPS database and ACPS paper.
  • Aug 06, 2021 update (v1.1.02): Updated the installer so that ACP files are now associated with ACPS.
  • March 06, 2022 update (v1.1.03): Corrected issue with saving FPA. Added FPA warnings before calculations.
  • Aug 13, 2022 update (v1.1.04): Corrected issue of resetting data to condition 1 in retreat screen after hiding window.
  • Sept 3, 2022 update (v1.1.06): Updated installer file.
  • Nov 17, 2022 update (v1.1.07): Updated help file and added guidance on remnant pillar in previous seam.
  • Feb 05, 2023 update (v1.1.08): Fixed issue with Zoom on mine plan view.
  • April 27, 2023 update (v1.1.09): (a) Fixed issue with plotting pillar sizes on angled cross-cuts (b) fixed plotting issues in several multiple seam graphs under metric units.
  • Aug 01, 2023 update (v1.1.10): Added the ACPS multiple seam database (Excel file) under Resources.

Click here to download the paper on ACPS which was presented at the 2018 International Conference on Ground Control in Mining, July 24-26, Morgantown, WV.

Click here to download the ACPS presentation to the 2018 Kentucky Professional Engineers in Mining Seminar (PEM) held in Lexington, KY on Sept 14, 2018.

Click here to download the latest ACPS help file in pdf format. This file will automatically be installed in your system upon installing ACPS.

The current version of the ACPS package is 1.1.10 and was released on Aug 01, 2023. Click here to download.