Q41GATE 2002MCQ

The time for a clay layer to achieve 85% consolidation is 10 years. If the layer was half as thick, 10 times more permeable and 4 times more compressible then the time that would be required to achieve the same degree of consolidation is

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📖 Explanation

\begin{aligned} k &=C_{v} m_{v} \gamma_{w} \\ T_{v} &=\frac{C_{v} t}{h^{2}} \\ \therefore \quad \text { and } \quad t_{1} &=\frac{h_{1}^{2} T_{v}}{k_{1}} m_{v} \gamma_{w} \\ \therefore \quad & t_{2}=\frac{h_{2}^{2} T_{v}}{k_{2}} m_{v} \gamma_{w} \\ & \frac{t_{1}}{t_{2}}=\left(\frac{h_{1}}{h_{2}}\right)^{2} \times \frac{T_{v}}{T_{v}} \times \frac{k_{2}}{k_{1}} \times \frac{m_{v 1}}{m_{v 2}}\\ \frac{t_{2}}{t_{1}} &=\left(\frac{h_{2}}{h_{1}}\right)^{2} \times \frac{k_{1}}{k_{2}} \times \frac{m_{v 2}}{m_{v 1}} \\ &=\frac{1}{4} \times 1 \times \frac{1}{10} \times 4=\frac{1}{10} \\ t_{2} &=\frac{t_{1}}{10}=\frac{10}{10}=1 \text { year } \end{aligned}

Q42GATE 2001MCQ

Identify the two FALSE statements from the following four statements. I. The consolidation of soil happens due to the change in total stress. II. When Standard Penetration Tests are performed in fine sands below the water table, the dilation correction is applied after the overburden correction is applied. III. Over consolidated clays will have predominantly cohesive strength as compared to the frictional strength. IV. Compaction of soils is due to expulsion of water.

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