1991-09-26_REVISION - C1981035 ‎(4)‎

• Permit No: C1981035
• IBM Index Class Name: REVISION
• Doc Date: 9/26/1991
• Doc Name: Updates and Modification to Wastebank Design
• From: National king Coal
• To: DMG
• Type & Sequence: TR1
• Media Type: D
• Archive: No

R WORKSHEET 3
----------------------------------------------------------------------
Worksheet #3 -- Slope Stability Analysis, Factor of Safety
----------------------------------------------------------------------�
Limit equilibrium analysis method, see attached sheets for derivation
;and equations.
i ,
;reference: Stability Analysis of Earth Slopes, Y.H. Huang, Van
Nostrand Reinhold Publ. , 71-78, 1983, ISBN 0-442-23689-1.
----------------------------------------------------------------------�
***** INPUT BLOCK *****
** SECTION ANALYZED: XS-4 (largest sectional area)
;Geometric Variables Soil Properties
Ll = 93 ft effective cohesion, c = 0.2 tsf
' L2 = 85 ft effect. frict. angle, f = 32 deg
i
alpha, a = 27 deg unit weight of waste,Gs = 86 lb/ft3
area,Al = 1162 sq-ft pore press. ratio, ru = 0.25
area,A2 = 774 sq-ft Wl, W2 - weight of each block
----------------------------------------------------------------------
***** COMPUTE QUADRATIC COEFFICIENTS *****
i
Wl = 99932 al = 30219.4 = 30219.4
' W2 = 66564 a2 = 33145.4 69524.1 34000.0 = 136669.5 ,
i
a3 = 10553.1 13285.9 = 23839.0 ,
----------------------------------------------------------------------
i
;Quadratic eq. for factor of safety, F: al*F^2 + a2*F + a3 =0 ,
***** TRIAL AND ERROR SOLUTION TO QUADRATIC *****
' F RHS F RHS
i
-------------------- ------------------ i
' 4 -87006 4.65 5933
i
' 4.2 -64780 4.66 -4486 ,
i
' 4.4 -40137 4.67 -3033
' 4.6 -13076 4.68 -1574
i
' 4.8 16403 4.69 -110 ,
i
' 5 48299 <--- 4.7 1361 <---- Solution
i
' S.2 82613 4.71 2838
----------------------------------------------------------------------
i
(FACTOR OF SAFETY = 4.7
----------------------------------------------------------------------