177_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

# 177_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 - 0...

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SL4 F N = Normal Force F H 04 Seepage _------JJ- ~ __ -- ------ -- - -·LII!·==T:=::S::=:--S-~~~~ Force ) o Consider a unit width slice of soil on an infinite slope with a surface angle ~: o Since the slope is infinite, the side forces are equal and opposite and can be ignored o Assume that the phreatic surface is at soil surface o For steady state seepage, the flow lines are parallel to soil surface and the equipotential lines are perpendicular to it. o The pore water pressure at base = u = 'Yw (Hcos ~)(cos ~) = 'Yw H cos 2 ~ o W = weight of slice = 'Ysat LH o EFH = T cos ~ - N sin ~ = 0 ~ T = N tan ~ o EF v = T sin ~ + N cos ~ - W = 0 ~ N tan ~ sin ~ + N cos ~ = W ~ N = 'Ysat LH cos ~ o Area which shear force acts on = _L_ cos~ N 'YHLcos~ 2 o normal stress =
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Unformatted text preview: 0' = (_L_J = (_L_J = 'YS8tHcos ~ cos~ cos~ T Ntan~ 1'satHLcos~tan~ . o shear stress = 't = (_L_J = (_L_J = (_L_J = 'Ys8tHcos~sln~ cos~ cos~ cos~ • Infinite Slope with Seepage o 't d = Cd + O"tant\ld = Cd +(j'Hcos 2 ~-'YwHCOS2 ~)tant\ld = Cd + yHcos 2 ~ = 't = 'Ys8tHcos~sin~ o--.SL = cos ~ sin ~- cos 2 ~i tan t\ld = cos 2 ~(tan ~-i tan t\ld) ~H ~ ~ o Cd = 'Ys8tHcoS2 ~(tan~-. ..i. .tant\ld) 1'sat . c tant\l o substitute Cd =-and tant\ld =--FS FS o get o if c FS= c 1" tant\l 'Ys8tHcoS2 ~tan~ +---'YS8t tan~ = o then FS y tan. 1 Can. J = 'YS8t tan~ = 2 tan~ and H = c cr cos 2 ~('Y sat tan ~-y tan t\l)...
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