---
title: "Lab and field permeability tests"
subject: "Soil Mechanics"
chapter: 6
key: "semester_4/soil_mechanics:permeability-test-names"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/permeability-test-names
site: BCT Engineering
---

# Lab and field permeability tests

Soil Mechanics · Chapter 6: Principle of Effective Stress, Capillarity and Permeability

- Asked in: 2074 Bhadra, 2 marks
- Video: [Constant Head Permeability Test](https://www.youtube.com/watch?v=B3gvVN29u8E) — 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/permeability-test-names
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-6

## Question

Write down the names of the testing methods for determining the coefficient of permeability in the laboratory and field.

## Short answer

Laboratory: constant head test (coarse soils), falling head test (fine soils), indirect methods like consolidation test or Hazen’s formula. Field: pumping out test, pumping in (auger hole) test, packer test (rock), and tracer tests.

## Answer

**Laboratory methods**
1. Constant head permeability test: for coarse-grained soils (sand, gravel).
2. Falling (variable) head permeability test: for fine-grained soils (silt, clay).
3. Indirect: from consolidation test; horizontal capillarity test; empirical formulae such as Hazen's $k = C\,D_{10}^2$.

**Field methods**
1. Pumping out test (unconfined and confined aquifer, with observation wells)
2. Pumping in test (auger hole / borehole test)
3. Packer test (for rock/deep strata)
4. Tracer tests.

## Check yourself

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

1. The constant head test suits:
   A. Clay
   B. Silt and clay
   C. Coarse-grained soils (sand, gravel)
   D. Rock only
   Answer: C. Coarse soils pass enough flow to measure under constant head. (Key point: Constant head)

2. The falling head test suits:
   A. Gravel
   B. Fine-grained soils (silt, clay)
   C. Clean sand only
   D. Rock
   Answer: B. Low flow in fine soils is measurable through a small standpipe. (Key point: Falling head)

3. Hazen's empirical formula for k is:
   A. k = C D10^2
   B. k = C D10
   C. k = C / D10
   D. k = C e^3
   Answer: A. k = C D10^2 with D10 the effective size. (Key point: Hazen's formula)

4. The packer test is used for:
   A. Soft clay
   B. Rock or deep strata
   C. Sand in a mould
   D. Laboratory samples
   Answer: B. Packer tests measure permeability of rock/deep strata in the field. (Key point: Field method for rock)

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