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52_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

# 52_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 - =...

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Degree of Consolidation Example: A surcharge load is applied to a clay layer. At a depth of 21 ft after 4 months find: a) the degree of consolidation b) excess pore pressure remaining c) total pore pressure d) vertical effective stress 3.0 ft 14.5 ft 14.0 ft uniform surcharge q = 2100 psf p35 =116pcf = 116 pcf before surcharge: =( ... .s')( "'PLIo)t- L3.r')(I""'pcl-): 'l,HL{YJ{ = (t.lr_~ I) ((,:1.11 pet) = ":l"?, pst: = ).3 ' .,- /IJ3= 1")..:)1 pst at time t = 0, uz,o = Uo = 2100 psf (water carries entire surcharge) (remember, only the clay consolidates!) , ......... -~S\-_ ,A., (''''I h.1 '-fl. J I) a) at t = 4 months Z = z = 3.5 ft = o. S' (H/N) (14 ft /2) T = c y t = 13.6ft2/ yr (4 mo)(1 yr/12 mol = (7. 0"1 ~s- (H/N)2 (14/2)2 fro P&B plot Uz,t
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Unformatted text preview: = 0.24, i.e. the degree of consolidation = 24% at 21 ft note: for Case 1 with T = 0.0925 the average degree of consolidation is U = 34.3°k b) Uz,t =(1-Uz,t ) ~ 0.24 = (1-Uz,t ) ~ IS'f {, (JSf. uz,o 2100 lU"t,l : ~ H~ fC-Mo.;.,;") ,). ( ol s.5 f ",.<:. .-~ILO fJr<: HvV't.) c) U = Uj + Uz,t = 'I?-3 I I PI (, ~ 2 11 ~ p s( d) ay = aYI + q = 23~~1 2/00::: 'f'1?l/ flS[ a'y = ay - U = 1'/'1'-/'" ~ +/1 :: /1 ~j psC or . '~ degree of consolidation U z = 0, ~ 1 •. {\J dcr'v-: o. l.lf ( ;( loa) :-!)oij IJ{ and a'y = a'yO + tia'y = 1'l"'}I . . ~o'/ : '14 r (lsf-...
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