Concrete Retaining Walls

A retaining wall is a structure designed and constructed to resist the lateral pressure of soil when there is a desired change in ground elevation that exceeds the angle of repose of the soil.There are two basic types of retaining wall concepts –”CANTILEVER” and “GRAVITY” are considered in Echo Prestressed hollow-core retaining wall designs.


This concept is a freestanding Echo Retaining wall without lateral support at its top or mechanical stabilization of the soil. These types of walls cantilever loads to large structural footings, converting horizontal pressures from behind the wall to vertical pressures on the ground. These walls require rigid concrete footings below ground that are cast with a heel and a toe, this is required to resist its overturning moment. This design limits the height of the wall to 5,0m maximum.

The gravity retaining walls are constructed on and with soil that is stabilized with manmade materials. This type of structure is able to retain the earth behind it by virtue of its weight. Gravity retaining walls have a degree of flexibility that allows them to adjust to minor deferential settlement without incurring structural damage.

An example of a fully supported retaining wall:

1. A kicker beam at the base.
2. Supported at level 1-3.
3.Temporarily anchored at level 3 prior to back filling – thereafter the anchoring is removed.

Gravity walling can be constructed in almost any situation where rapid change of grade is desired. Gravity walling confines the soil or other fill material allowing the material to behave as a reinforced mass. This walling solution can be used in both cut and fill applications.

Gravity retaining walls must have sufficient weight and width or be otherwise supported so that it does not overturn or slide forward due to external forces being exerted upon it. The wall must also be able to hold together all individual precast hollow-core slabs as a unit in order to function that is, the wall must be stable with respect to both the external forces that might cause it to fall and the internal forces that might cause it to lose its shape and / or deformed.

The Echo retaining wall must be designed to be stable with respect to four potential external failure modes:

  • Global stability: FSgl=1.5
  • Base sliding: FSsl=1.5
  • Overturning: FSot=2.0
  • Bearing capacity: FSbc=2.0

Internal stability refers to the ability of individual Echo Prestressed Hollow-core slabs of the retaining wall to act as one single unit.
The wall must be designed so that the individual slabs of the wall do not pull out, separate, or slide apart.
This is achieved with either of the following options.

  • Echo standard edge profile : The grout in the joints with the key formed in the slab edges.
  • Echo adapted edge profile : The tongue and groove (T & G) this is an Interlocking profile.

The Echo retaining wall concept, by itself or in combination with Geogrid is as effective as more costly alternatives such as: Cast in-situ; steel reinforced concrete retaining walls; modular block walls; or Gabion basket walls.

  • Increased productivity/reduced on site labour.
  • The Echo retaining wall method of construction is three times faster than cast in-situ.
  • Efficient light weight section. The depth and the reinforcing configuration can be varied to suit the wall height and load requirements.
  • Service openings for air – conditioning ducts etc. can be accommodated without difficulty.
  • Finished surfaces: – Pre finished in a factory to give a durable and aesthetically pleasing appearance.
  • Earth retaining – the structural capacity of the panels can be utilised to retain fill material to a height specified by the principal engineer.
  • The prestressed wall is 100% vertical, thus saving substantial space on site, compared with retaining block walls which are constructed at an angle.
  • Echo offer the full turn-key package which offers a full retaining or security wall solution.