Bieniawski Coal Pillar Strength Calculator

Underground Coal Mining Geomechanics: Calculate ultimate pillar compressive strength ($\sigma_p$), tributary overburden stress ($\sigma_v$), and safety factors ($SF$).

Pillar Geometry & Mining Depth

Pillar Width $w_p$ (m):

Mining Seam Height $h$ (m):

Entry / Room Width $B$ (m):

Depth of Cover $H$ (m):

Rock & Coal Mass Properties

In-Situ Coal Strength $\sigma_c$ (MPa):

Overburden Density $\gamma$ (kN/m³):

Stability & Load Analysis

Pillar Safety Factor ($SF$)

Target: SF ≥ 1.50 (Main Entries)

Pillar Strength ($\sigma_p$)

-- MPa

-- psi

Average Pillar Load ($\sigma_{\text{load}}$)

-- MPa

Virgin Stress: -- MPa

Areal Extraction Ratio ($e$)

-- %

Width/Height Ratio: --

Design Guidelines:

• $w/h \ge 5.0$: Squat pillar confinement prevents sudden catastrophic violent burst.

• Recommended Safety Factors: Mains $\ge 1.6 - 2.0$, Submains $\ge 1.5$, Production panels $\ge 1.3$.

• Tributary area theory assumes uniform stress distribution across the entire extraction tributary.

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Bieniawski Coal Pillar Strength Calculator

Pillar Geometry & Mining Depth

Rock & Coal Mass Properties

Stability & Load Analysis

Frequently Asked Questions