GATE 2018 CE (CE1) – Question 56
Soil has void ratio 0.55 at effective normal stress 140 kPa and compression index 0.25. To reduce void ratio to 0.40, the required effective-stress increase, to one decimal, is ______ kPa.
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Correct answer: 416.0 to 420.0
Explanation
Use $e_1-e_2=C_c\log_{10}(\sigma_2^\prime/\sigma_1^\prime)$. Thus the log stress ratio is $(0.55-0.40)/0.25=0.6$, giving final stress $140(10^{0.6})=557.350$ kPa. The requested increase is $557.350-140=417.4$ kPa.