GATE 2022 CE (CE2) – Question 55
A saturated compressible clay layer of thickness h is sandwiched between two sand layers, as shown in the figure. Initially, the total vertical stress and pore water pressure at point P, which is located at the mid-depth of the clay layer, were 150 kPa and 25 kPa, respectively. Construction of a building caused an additional total vertical stress of 100 kPa at P. When the vertical effective stress at P is 175 kPa, the percentage of consolidation in the clay layer at P is _____________. (in integer)
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Correct answer: 50
Explanation
Initial effective stress is $150-25=125$ kPa. Ultimately the 100 kPa added load transfers to the soil skeleton, giving 225 kPa.
At the stated instant the effective-stress increase is 175−125=50 kPa, so local degree of consolidation is $50/100=\mathbf{50\%}$.