---
title: "Causes of preconsolidation"
subject: "Soil Mechanics"
chapter: 9
key: "semester_4/soil_mechanics:preconsolidation-causes"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/preconsolidation-causes
site: BCT Engineering
---

# Causes of preconsolidation

Soil Mechanics · Chapter 9: Compressibility of Soil

- Asked in: 2074 Bhadra, 2 marks
- Video: [Determination of Preconsolidation Stress | Elementary Engineering](https://www.youtube.com/watch?v=DtN5ufXMcOg) — 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/preconsolidation-causes
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-9

## Question

What are the different causes of preconsolidation of soil?

## Short answer

Preconsolidation is caused by erosion or removal of overlying soil, melting of glaciers, desiccation, lowering and later rise of water table, removal of structures, and secondary compression, aging, cementation, or tectonic effects.

## Answer

A soil is preconsolidated when it has once carried a greater effective stress than at present. The causes are:

1. **Erosion** or removal of overlying soil layers.
2. **Melting of glaciers/ice sheets** which once loaded the soil.
3. **Desiccation** (drying) of the upper soil layer, which causes capillary stress, followed by re-wetting.
4. **Lowering and later rise of the water table**, or fluctuations of the ground water level.
5. **Removal of buildings or other structures** (past loading and unloading).
6. **Secondary compression, aging and cementation** (chemical effects), and tectonic effects.

## Check yourself

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

1. A soil is preconsolidated when it
   A. has never been loaded
   B. once carried a greater effective stress than at present
   C. is partially saturated
   D. has high permeability
   Answer: B. Preconsolidation means past effective stress exceeded the present one. (Key point: Definition)

2. Which is a cause of preconsolidation?
   A. Erosion of overlying soil
   B. Rapid loading by a new building
   C. Rise in clay content
   D. Increase in void ratio only
   Answer: A. Removal of overlying layers by erosion leaves the soil with a past higher stress. (Key point: Unloading causes)

## Related in Soil Mechanics

- [Settlement with preconsolidation 125 kPa](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aprimary-consolidation-settlement-preconsolidated) — Soil Mechanics, chapter 9
- [NC/OC clay, e-log p, preconsolidation](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aconsolidated-clay-e-log-p-preconsolidation) — Soil Mechanics, chapter 9
- [Causes of slope failure](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aslope-failure-causes) — Soil Mechanics, chapter 11, asked 4×
- [Compressibility and its causes](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Acompressibility-causes) — Soil Mechanics, chapter 9

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