GENERAL46230

• Permit No: C1981016
• IBM Index Class Name: General Documents
• Doc Date: 5/6/1981
• Doc Name: MEMO
• Permit Index Doc Type: GENERAL CORRESPONDENCE
• Media Type: D
• Archive: No

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;~~ ~'~i•r.:i•~r`i,r'i~`i~ [~r~tii~ul['~.1:•~•u`.1.:~. I .. _ ~ /.. ~ _ .:. ~ .
r 111..I//ii~ ___ q
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- 'ti`=` - ~ calculations made with logarithmic spiral and circular arc as (ailuit sari .
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_ -_ _ _ _ _-_ __ ~ give_very close results. Extensive studies by Swedish rnginern n(slope fa i'
- _ - •_~ _ ~'_.'~~y in cla Burin ~ the rrrl -
-'- y ~ g y part of this ceniury' also rcveakd the[ [he fa
'~ - --D/It = u , ,~- • ~'. surface closely approaches the circular. arc: Th_r analysis of shpt ira~
~~ ---n'/r ^ 1 '.' ~~ `using a''circtllar slip surface was ilevrloped b_y' Fellenitls (1y36) and ct.
`= I \` _.__ - - •, - • ` - _'~'and is often referred to :isahe S~rcrAisll cirrlr idethoJ.,Fi;ure J.'_2 sho~ii
.._ ~~'~. ._ 1 displacemeui of the soil mass produced by :i slope failure. ,
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Fib. 5:!II.Oauing capa:it) numhrn (or Liwula•
' liana with inclined loads,. rAfler Atcyerhotf(I`liJ).~

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Ir~:~. S:!1. Circular arc mcihod ul' ~lopc an,llysis.
Cvru/ur arc nlefhod. Ficurc S'1(u) shows a soil m;lsi bounded hv'`
slip sur(acr aGcd. Since the circular arc is an :ustiiiled ,lip sur(nct, its pusiti.
is nut dttenninate. Thr err ubrd is therefore an arbnranlp asiume.! arc. T. .'
Fumes acting uli ihr soil Ill:IiS fr/Yl/:Ifr tltr w'CICI71 Jf the SOII Illai) tl' aml '
force on the failure surlau. The force im :iny elrntent he rf the slip sur..
' .is rumpuxd of a normal component dF, and shear or ran_•rntial componc
r/F, parallel to it.:~.t failure, dF, must br prjual to dte shear strr~eth of t'-
soil :u cxprtssal by Ey. (7._')• which in~this case can be written as
r/F, = c dl -!- r/F, tan q