RETAINING WALL

Retain soil at a slope which is greater than it would naturally assume, usually at a vertical or near vertical position.

In building work, retaining wall are required to support difference in level of soil, fuel, chemical and waste material-solid or liquid.

The major function of any retaining wall is to act as on earth retaining structure for the whole or part of its height on one face, the other being exposed to the elements.

BASIC FUNCTION OF RETAINING WALL

The design of any retaining wall is basically concerned with the lateral pressures of the retained soil and any subsoil water.

It must be design to ensure that:

(i) Overturning does not occur

(ii) Sliding does not occur

(iii) The soil on which the wall rest is not overloaded (It may fail due to the loss of bearing capacity of the soil supporting the base)

(iv) The materials used in construction are not overstressed

DESIGN PRINCIPLES

DESIGN PRINCIPLES

FAILURES OF RETAINING WALL

Retaining wall must be designed to resist the following factors:

Overturning

Overstressing of the material in the wall

Forward sliding

Settlement due to overstressing of soil under the wall

Circular slip/slip plane

FAILURES OF RETAINING WALL

There are several type of retaining wall:

(i) Gravity Wall / Mass Retaining Wall

- constructed of brickwork, masonry, mass concrete or

enclosed soil

(ii) Cantilever Walls

- constructed of reinforced concrete

(iii) Counterfort Retaining Wall

- constructed of reinforced or pre-stressed

(iv) Pre-cast Concrete Retaining Walls

(v) Pre-cast Concrete Crib retaining Walls

(vi) Reinforced Masonry Retaining wall

TYPES OF RETAINING WALL

TYPES OF RETAINING WALL

GRAVITY WALLS

Sometimes called mass retaining wall.

There are generally only economic up to a height of 1.800m.

Mass walls can be constructed of semi-engineering quality bricks, stone, or plain concrete.

TYPES OF RETAINING WALL

CANTILEVER WALLS

Usually of reinforced concrete and work on the principles of leverage

Two basic forms can be considered, a base with a large heel so that the mass of earth above can be added to the mass of the wall for design purpose.

Reinforced cantilever walls have an economically constructed using pre-stressing techniques.