---
title: "Foundation settlement causes and treatment"
subject: "Building Technology"
chapter: 2
key: "semester_6/building_technology:foundation-settlement-treatment"
source: https://www.bctengineer.com/q/semester_6/building_technology/foundation-settlement-treatment
site: BCT Engineering
---

# Foundation settlement causes and treatment

Building Technology · Chapter 2: Foundations

- Asked in: 2066 Bhadra (old course), 16 marks
- Video: [How to Prevent Differential Settlement in Foundation | Settlement in foundation | soil settlement](https://www.youtube.com/watch?v=zTB_3xbtqr0) — Civil Engineering Mastery
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/foundation-settlement-treatment
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Define foundation with its types. What are the causes of foundation settlement and how can we provide treatment for foundation settlement?

## Short answer

A foundation is the lowest part of a structure transferring loads to the ground; types include shallow (spread, strip, raft) and deep (pile, pier, well). Settlement is caused by consolidation, weak or non-uniform soil, water table changes, overloading, adjacent works and earthquakes. Treatment includes underpinning, enlarging footings, grouting, drainage, load reduction, piles/micropiles and crack repair.

## Answer

#### Foundation
A **foundation** is the lowest part of a structure, in direct contact with the ground, which transfers the loads of the structure safely to the soil.

#### Types
- **Shallow foundations**: spread (isolated) footing, strip (wall) footing, combined footing, strap footing, raft (mat) foundation, grillage.
- **Deep foundations**: pile foundation, pier foundation, well (caisson) foundation.

```text
 Shallow: [__|__]      Deep:  |   |   |   piles
 ----------------------     weak soil
                            ===hard layer===
```

#### Causes of foundation settlement
1. **Consolidation** of compressible clay and silt layers under load.
2. **Weak, loose or filled soil** and poor compaction.
3. **Non-uniform soil strata**, giving differential settlement.
4. **Lowering of ground water table** or seasonal shrinkage and swelling of clay.
5. **Overloading** or unequal loading of foundation.
6. **Adjacent excavation and construction**, and vibrations.
7. **Tree roots** drawing moisture.
8. **Loss of soil by erosion or leakage**, and underground voids.
9. **Earthquake** causing densification and liquefaction.
10. **Faulty design or construction**: footing too small or shallow.

#### Treatment of settlement
1. **Underpinning**: Pit method, pile method, or by extending the footings deeper to a firm stratum.
2. **Enlarging the foundation** to spread the load.
3. **Soil improvement**: Grouting (cement, chemical), compaction grouting, jet grouting.
4. **Drainage**: Control surface and ground water, repair leaking pipes.
5. **Reducing the load**, or tying the structure with beams.
6. **Pile or micropile** supporting under existing footing.
7. **Removal of trees**, or root barriers.
8. **Repair of cracks** after settlement is stabilised.

## Check yourself

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

1. A foundation is
   A. The roof
   B. A wall finish
   C. The lowest part that transfers loads safely to the soil
   D. A DPC
   Answer: C. It is in contact with the ground. (Key point: Foundation)

2. Consolidation causing settlement occurs in
   A. Hard rock
   B. Compressible clay and silt
   C. Gravel only
   D. Steel
   Answer: B. Water squeezes out of clay under load. (Key point: Consolidation)

3. Underpinning is
   A. Painting footings
   B. Removing footings
   C. Extending footings deeper to a firm stratum by pit or pile methods
   D. Raising the roof
   Answer: C. It transfers load to firm soil. (Key point: Underpinning)

4. When are cracks repaired?
   A. Before any settlement
   B. Never
   C. After settlement has stabilised
   D. During settlement
   Answer: C. Repair is done once movement stops. (Key point: Repair timing)

## Related in Building Technology

- [Foundation settlement causes and underpinning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asettlement-underpinning-067as) — Building Technology, chapter 2
- [Foundation settlement, effects, black cotton soil](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asettlement-black-cotton-062ba) — Building Technology, chapter 2
- [Causes of foundation failure](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-failures) — Building Technology, chapter 2, asked 2×

## Related in other subjects

- [Treatment processes, impurities removal, settlement](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Atreatment-impurities-sedimentation-factors) — Water Supply Engineering, chapter 6, asked 2×
- [Foundation treatment before gravity dam construction](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Afoundation-treatment-gravity-dam) — Hydropower Engineering, chapter 4
- [Proportioning footings for uniform settlement](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aproportion-footings-uniform-settlement) — Foundation Engineering, chapter 6, asked 2×
- [Clay 10 m, 2.54 cm sample, half settlement](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aclay-10m-half-settlement-time-ratio) — Soil Mechanics, chapter 9