1. A fill is to be placed over the soil profile shown below. The groundwater tab
ID: 1921073 • Letter: 1
Question
1. A fill is to be placed over the soil profile shown below. The groundwater table is level with the original ground surface. (a) Divide the clay layer into 7 sublayers with the following respective thickness: 2 ft, 2 ft, 2 ft, 2 ft, 2 ft, 2 ft, and 1 ft. Calculate the ultimate primary consolidation in the clay layer. (b) Calculate the time factor T and average degree of consolidation U at the following respective time after the placement of the fill: 0.25 yrs, 0.5 yrs, 0.75 yrs, 1 yrs, 2 yrs, 5 yrs, 10 yrs. (c) Develop a plot of consolidation settlement versus time. Comment on the plot.Explanation / Answer
A) initial effective stress at mid depth of clay layer before placing fill
= (100*13)- (10*13)= 1170 lb/sq.ft assuming Yw=10lb/cu.ft.
effective stress after fill will be = (118*10)+(100*13)- (10*13)=2350 lb/sq.ft
therfoer change in effective stress dp=2350-1170=1180lb/sq.ft
given that Cc/(1+e)=0.180
therfore therfore de/(1+e)= .180*log(2350/1170)= 0.05452
therfore primary consolidation = 0.05452*13= 0.708 ft
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