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EXAMPLE CALCULATION <br />T.A.L. _ (120)(120)(158)(1200) = 1,365,120 tons <br />• ~ 2000 <br />off = [6.944 X 10'3 (158)(1200)] = 1,317 psi <br />Tan B = 1 + Sin 40° = 4.60 <br />1 - Sin 40° <br />o „ _[(1,317)(4.60) + 600] = 6,657 psi <br />Y = 13 In 6,657 = 4,05 ft, <br />4,60 (4,60-1) 600 <br />L = 7.2 X 10-2 (6,657) [1002-2(100)(4.05) + 4 (4.05)2] <br />3 <br />= 4,415,286 tons <br />Safety Factor = 4,415,286 = 3.23 <br />1,365,120 <br />• Pillar loading for all pillars was estimated on the basis of full (maximum) <br />tributary area loads, i.e, halfway to each adjacent pillar and all the way <br />to the surface. Although load transfer distances could be used, T.A.L, will <br />gig ~ the n~ost conservative estimate. <br />An initial comparison can be made between the East Mains and the 1st West <br />Mains to determine if the area directly under the Renewable Resource Lands <br />will be permanently stable. The strength of the 1st West Mains is then com- <br />pared to the strength of the West Main panels. Two analyses of West Main <br />panels are done, one being adjacent to the 1st West Mains under 600 ft, of <br />overburden and another adjacent to partial pillaring at 800 ft. of over- <br />burden. <br />All pillar sizes analyzed in this report are adequate for permanent support <br />with safety factors greater than 1.5. <br />• The following table summarizes these safety factors, <br />