Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to (typically a steep, near-vertical or vertical slope). Retaining walls may fail by overturning, failure of the foundation or by sliding.
ESP are able to undertake Site Investigation and Geotechnical Tests to assess material properties to support the design of new retaining structures, and to investigate and remedy those which may have failed.
Forces acting upon structures retaining soil can be considered in terms of earth pressure. There are three main types of earth pressure that bear upon the movement of the wall:
Earth pressure at rest: This applies when the wall is at rest and the material is in its natural state.
Active earth pressure: As the wall moves away from the backfill, there is a decrease in the pressure on the wall which continues until reaching a minimum value that then remains constant.
Passive earth pressure: As the wall moves towards the backfill, there is an increase in the pressure on the wall which continues until reaching a maximum value that then remains constant.
Very broadly, retaining walls are ‘cut’ walls, in which the wall is cut into the existing slope, or ‘fill’ walls in which the retaining wall is built in front of the slope, and then the space behind It is filled. There is a wide variety of types of retaining walls and some typical examples are presented below:
Other examples can involve free-draining gabion baskets, green/cellular walls, reinforced soil, crib-walls, and anchored earth walls using soil nails.
Retaining walls may fail by overturning, failure of the foundation or by sliding. There is both a vertical force and a lateral force operating on them, and the combination tends towards overturning. When designing and building a retaining wall, there are a variety of factors to consider. Before you begin designing your wall and choosing the aesthetics, you need to understand the location and environmental factors that can make your wall fail. Building a retaining wall takes advanced planning and careful design in order to avoid it becoming a hazard.
Examples of ESP experience:
- Symonds Yat Landslide: Site Investigation and Development of Conceptual ground Model to assess landslide mechanisms occurring and affecting a complex of retaining walls.
- Mumbles Road Retaining Wall Failure: Review of factors affecting and mechanisms occurring which may have contributed to retaining wall failure.