Laserfiche WebLink
<br />TABLE III.4 <br />MINIMUM FACTOR OF SAFETY AGAINST PILLAR FAILURE <br /> <br />MINING <br />METHOD LOCATION DEPTH (FT) PILLAR <br />HEIGHT <br />(FT) LOAD <br />TRANSFER <br />DISTANCE <br />(FFT) MIN. <br />FACTOR OF <br />SAFETY' APPROX. <br />PILLAR <br />SIZE <br />ROOM & <br />PILLAR RP1 400 7.5 NIA 3.19 <br /> RP2 400 8.0 N/A 3.50 <br />LONGWALL LW1/LW2 600 8.4 148 1.76 80x100 <br /> LW21LW3 700 8.3 171 1.58 80x100 <br /> LW3/LW4 850 8.5 204 1.37 80x100 <br /> LW41LW5 950 8.7 226 1.27 80x100 <br /> LWS/LW6 1000 8.8 236 1.22 80x100 <br /> LW6/LW7 1150 9.1 266 1.22 85x100 <br /> LW7/LWB 1250 8.8 285 1.21 95x120 <br /> LW8/LW9 1345 8.5 302 1.22 97x120 <br />'Assumes angle of internal friction (on of 38.50 and pillar edge strength of 560 psi. <br />• Permit Renewal #3 (Rev, 8/99) III-18 <br />