Shallow Foundations

Settlement

G. R. Dodagoudar

DEPARTMENT OF CIVIL ENGINEERING

I I T MADRAS, CHENNAI - 600 036.

See!

Understand!

Understand!

Introduction

A comparison !

Results from elastic theory indicate that the increase

in vertical stress in the soil below the centre of a strip

footing of width B is approximately 20% of the

foundation pressure at a depth of 3B.

In the case of a square footing the corresponding

depth is 1.5B.

For practical purposes these depths can normally be

accepted as the limits of the zones of influence of the

respective foundations and are called the significant

depths.

An alternative approach is to take the significant

depth as that at which the vertical stress is 20% of the

effective overburden pressure. It is essential that the

soil conditions are known within the significant depth

of any foundation.

It is practically impossible to prevent settlement of

shallow foundations.

At least, elastic settlement will occur.

Your task as a geotechnical engineer is to prevent

the foundation system from reaching a

serviceability limit state.

Total Settlement

Some Facts !

Immediate Settlement

Immediate Settlement

Solution:

Example 2

Example 3

Example 4

Example 5

Set-up for plate load test

Set-up for plate load test

Procedure

For square footings in granular soils

Problems