PERMFILE132017

• Permit No: C1981044
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 44 Subsidence Monitoring
• Media Type: D
• Archive: No

SubTerra, Inc. Pillar Stability Evaluation -EMPIRE MINE 3/26/95
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Pillar Stability using Bienawski's Pillar Strength Equation:
P~oad = 1.1 * h * Ap/At i
Where,
h =Depth (ft)
Ap =Area of Pillar
At =Total area supported by pillar
Pstrength =CRMS * (0.64 + 0.36(Wp/Hp))
Where,
Wp =Pillar Width
Hp =Pillar Height
CRMS =Coal Rock Mass Strength
1=.5 = Pstrength ~ Pload
CRWMS =UCsample * (Dsample~ s) ~ 6)
where,
UCsample = Uniaxial compressive strength of sample
Dsamp,e = Diameter of sample

h (ft) 1000 Wentry 20 Eratio (%) 36
Ap 6500 Wp 65 CRMS 765
At 10200 Hp 10
UCsample 2650 Lp 100

Pload = 1726
Pstrength = 2280
FS = 1.32

Notes:
1. The compressive strength used in the calculation was for a poor quality core
specimen. The actual coal strength is expected to be much larger.

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