A 2.5 cm thick sample of clay was taken from the field for predicting the time of settlement for a proposed building which exerts a uniform pressure of 100 kN/m^2 over the clay stratum. The sample was loaded to 100 kN/m^2 and proper drainage was allowed from top and bottom. It was seen that 50

Question

A 2.5 cm thick sample of clay was taken from the field for predicting the time of settlement for a proposed building which exerts a uniform pressure of 100 [latex]100 \mathrm{kN} / \mathrm{m}^{2}[/latex] over the clay stratum. The sample was loaded to 100 [latex]\mathrm{kN} / \mathrm{m}^{2}[/latex] and proper drainage was allowed from top and bottom. It was seen that 50 percent of the total settlement occurred in 3 minutes. Find the time required for 50 percent of the total settlement of the building, if it is to be constructed on a 6 m thick layer of clay which extends from the ground surface and is underlain by sand.

Accepted Answer

T for 50% consolidation = 0.197.

The lab sample is drained on both sides. The coefficient of consolidation [latex]C_{y}[/latex] is found from

[latex]c_{v}=\frac{T H_{d r}^{2}}{t}=0.197 imes \frac{(2.5)^{2}}{4} imes \frac{1}{3}=10.25 imes 10^{-2} \mathrm{~cm}^{2} / \mathrm{min}[/latex]

The time t for 50% consolidation in the field will be found as follows.

[latex]t=\frac{0.197 imes 300 imes 300 imes 100}{10.25 imes 60 imes 24}=120 ext { days. }[/latex]

Question 7.8: A 2.5 cm thick sample of clay was taken from the field for p...

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