---
title: "Shear strength tests (lab and field)"
subject: "Soil Mechanics"
chapter: 10
key: "semester_4/soil_mechanics:shear-strength-tests-names"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/shear-strength-tests-names
site: BCT Engineering
---

# Shear strength tests (lab and field)

Soil Mechanics · Chapter 10: Shear Strength of Soil

- Asked in: 2073 Bhadra, 2 marks; 2078 Baisakh, 1 marks; 2078 Poush, 3 marks (asked 3 times)
- Video: [Direct Shear Test | Elementary Engineering](https://www.youtube.com/watch?v=1Cwyuu7ve90) — Elementary Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/soil_mechanics/shear-strength-tests-names
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-10

## Question

List out / name the laboratory and field tests for determining the shear strength parameters of the soil. Also state which tests are appropriate for which type of soil.

## Short answer

Lab tests include direct shear, triaxial (UU, CU, CD), unconfined compression, vane, ring shear. Field tests: vane, SPT, CPT, pressuremeter, plate load. Sands: direct shear, CD triaxial, SPT/CPT. Soft clays: UU, UCS, vane. Stiff clays: UU/CU. Long-term clay: CD/CU with pore pressure.

## Answer

**Laboratory tests**

1. Direct shear test (shear box).
2. Triaxial compression test: unconsolidated undrained (UU), consolidated undrained (CU) with or without pore pressure measurement, and consolidated drained (CD).
3. Unconfined compression test (UCS).
4. Laboratory vane shear test.
5. Ring shear test (for residual strength).

**Field tests**

1. Field (in-situ) vane shear test.
2. Standard Penetration Test (SPT).
3. Cone Penetration Test (CPT / static cone).
4. Pressuremeter test.
5. Plate load test.

**Suitable tests for each soil**

| Soil type | Appropriate tests |
|---|---|
| Clean sand and gravel (cohesionless) | Direct shear; CD triaxial; SPT and CPT in the field (undisturbed samples are hard to get) |
| Soft to medium saturated clay | UU triaxial, UCS, laboratory and field vane shear |
| Stiff or fissured clay | UU and CU triaxial; UCS not reliable if fissured |
| Clay with long-term (drained) loading | CD or CU with pore pressure measurement (effective stress parameters) |
| Silts and silty sands | Direct shear (drained); CU triaxial |
| Residual strength of clay (slope failures) | Ring shear; reversal direct shear |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which list contains only tests that determine shear strength?
   A. Sieve analysis, Atterberg limits, specific gravity, proctor
   B. Direct shear, falling head, consolidation, hydrometer
   C. Triaxial, sand cone, Liquid limit, vane shear
   D. Direct shear, triaxial, unconfined compression, vane shear
   Answer: D. Direct shear, triaxial, UCS and vane shear tests all measure strength parameters. (Key point: Tests for shear strength)

2. Which tests suit soft to medium saturated clay?
   A. Direct shear and SPT only
   B. UU triaxial, UCS, and vane shear
   C. CPT and plate load only
   D. Ring shear only
   Answer: B. Soft saturated clay is tested undrained for short-term strength, using UU, UCS and vane tests. (Key point: Test for soft clay)

3. Which are appropriate for clean sand and gravel?
   A. UCS and lab vane shear
   B. UU triaxial and UCS
   C. Direct shear and CD triaxial in the lab, SPT and CPT in the field
   D. Ring shear only
   Answer: C. Sand is cohesionless, drained and hard to sample undisturbed, so drained tests and field penetration tests are used. (Key point: Test for clean sand)

4. Which test gives residual strength of clay for slope failures?
   A. Unconfined compression test
   B. Field vane test
   C. Standard penetration test
   D. Ring shear test
   Answer: D. Ring shear permits large continuous displacement to reach residual strength. (Key point: Residual strength)

## Related in Soil Mechanics

- [Lab and field permeability tests](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Apermeability-test-names) — Soil Mechanics, chapter 6
- [Shear tests; direct shear calculation](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Ashear-tests-direct-shear-strength-calc) — Soil Mechanics, chapter 10
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- [UCS test soil type and parameters](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aunconfined-compression-soil-type-mohr) — Soil Mechanics, chapter 10
- [Role of effective stress in shear strength](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Arole-effective-stress-shear-strength) — Soil Mechanics, chapter 6

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