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GATE 2022 CE (CE1) – Question 17

Geotechnical Engineering · Permeability and seepage: flow nets, uplift pressure, piping, capillarity · 1 mark · Multiple choice

Four different soils are classified as CH, ML, SP, and SW, as per the Unified Soil Classification System. Which one of the following options correctly represents their arrangement in the decreasing order of hydraulic conductivity?

  1. SW, SP, ML, CH
  2. CH, ML, SP, SW
  3. SP, SW, CH, ML
  4. ML, SP, CH, SW

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Correct answer: (A) SW, SP, ML, CH

Explanation

Coarse granular sands generally conduct water much more readily than silts, while high-plasticity clays have very low conductivity. This places the two sands first, ML next and CH last.

Among the offered choices, **SW, SP, ML, CH (A)** is the only one with that broad order. However, USCS labels alone cannot reliably order the two sands: their grain sizes and fines content are not specified.