Room-and-Pillar Layout Designer

Tributary-area stress + Bieniawski pillar strength, plan view

FS ≥ 1.5 safe 1.0–1.5 marginal < 1.0 unsafe

Pillar width W_p 15 m

Room (opening) width W_r 6 m

Seam / pillar height H_p 3 m

Depth of cover H 200 m

Overburden density γ 2500 kg/m³

In-situ strength S₁ 6.2 MPa

Layout

Extraction ratio

–

fraction of seam removed

Tributary-area pillar stress σp

–

σp = γ·H / (1−e)

Pillar strength Sp (Bieniawski)

–

Sp = S1·(0.778+0.222·Wp/Hp)

Safety factor FS = Sp / σp

–

Recovered ore rate

–

relative to full seam removal