Analysis of ARMPS2010 database with LaModel and an updated abutment angle equation

Area of Science:

• Mining Engineering
• Geotechnical Engineering
• Rock Mechanics

Background:

• The Analysis of Retreat Mining Pillar Stability (ARMPS) program, developed by NIOSH, aids U.S. coal mines in designing safe retreat room-and-pillar panels.
• ARMPS utilizes geometric computations and empirical rules, including the "abutment angle" concept, to determine in-situ and mining-induced loads on pillars adjacent to gobs.

Purpose of the Study:

• To back analyze stress measurements from U.S. and Australian mines with diverse overburden geologies.
• To evaluate the accuracy of the ARMPS program's abutment angle for varying depths and overburden conditions.
• To develop and validate a new equation for calculating abutment angles in deeper mining scenarios.

Main Methods:

• Stress measurements from various mines were back analyzed to assess the ARMPS program's empirical abutment angle.
• A new equation for abutment angle calculation was formulated, incorporating the panel width to overburden depth ratio.
• The new equation was tested using ARMPS2010 and LaModel against the ARMPS2010 case history database.

Main Results:

• The ARMPS empirical abutment angle of 21° was supported by case histories for depths less than 200 m.
• For depths exceeding 200 m, the actual abutment angle was found to be significantly less than the 21° empirical value.
• The newly developed abutment angle equation, when used with LaModel, demonstrated good classification accuracy for deep cover cases compared to ARMPS2010.

Conclusions:

• The standard ARMPS abutment angle requires adjustment for deeper coal mining operations.
• A novel equation based on the panel width to overburden depth ratio provides more accurate abutment angle estimations for deep cover.
• The improved abutment angle calculation enhances the prediction of mining-induced loads, particularly in deeper mines.