GATE CE 2023 Set 1 — Question 18

MCQ+1 / -0.33MediumTriaxial TestShear Strength of SoilsGeotechnical EngineeringDirect Shear TestStability of Slopes

Geotechnical Engineering → Shear Strength of Soils → Direct Shear Test

Last updated 5 September 2026

Question

A possible slope failure is shown in the figure. Three soil samples are taken from different locations (I, II and III) of the potential failure plane. Which is the most appropriate shear strength test for each of the sample to identify the failure mechanism? Identify the correct combination from the following options: P: Triaxial compression test Q: Triaxial extension test R: Direct shear or shear box test S: Vane shear test

Correct answer (A) I-Q, II-R, III-P Solution The appropriate shear strength test depends on the stress state at different points along the failure surface: 1. Location I (Active Zone/Top of Slope): The soil is being stretched horizontally as it moves downward. This state of stress, where the horizontal stress decreases, is best simulated by a Triaxial extension test (Q) . 2. Location II (Middle of Failure Plane): The failure is primarily due to sliding along a relatively flat portion of the failure surface. This is best simulated by a Direct shear or shear box test (R) . 3. Location III (Passive Zone/Toe of Slope): The soil at the toe is being compressed by the weight of the sliding mass above it. This state of stress is best simulated by a Triaxial compression test (P) . Therefore, the correct combination is I-Q, II-R, III-P. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (A) I-Q, II-R, III-P Solution The appropriate shear strength test depends on the stress state at different points along the failure surface: 1. Location I (Active Zone/Top of Slope): The soil is being stretched horizontally as it moves downward. This state of stress, where the horizontal stress decreases, is best simulated by a Triaxial extension test (Q) . 2. Location II (Middle of Failure Plane): The failure is primarily due to sliding along a relatively flat portion of the failure surface. This is best simulated by a Direct shear or shear box test (R) . 3. Location III (Passive Zone/Toe of Slope): The soil at the toe is being compressed by the weight of the sliding mass above it. This state of stress is best simulated by a Triaxial compression test (P) . Therefore, the correct combination is I-Q, II-R, III-P.

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