We have carried out the design of many earth and water retaining structures and have considerable experience in this field.
Due to the varying nature of sub-soils and the surrounding environment, retaining walls require design analysis. Retaining wall designs need to take into account the slope of the ground behind the wall, height of the wall, the nature of the soil and ground water levels. The strength of foundations also requires consideration.
Many years ago there used to be a rule of thumb that the thickness of a mass masonry retaining wall should be one third of the height. This was often quite adequate for garden walls, but due to the varying nature of sub-soils, topography of land and surrounding environment, this does not always work. Any retaining wall has to be properly designed, taking into account the slope of the ground behind the wall, height of the wall, nature of soil and ground water levels.
The following are typical retaining wall systems for which we have experience:
Mass masonry walls consist of a mass of masonry such as concrete blockwork and/or stone and the mass weight of the wall holds back the soil. The bond of the masonry helps withstand more load than a dry stone wall. The wall can be faced with stone, brickwork or in fact any finish for aesthetics.
Reinforced masonry walls consist of two skins of blockwork with a reinforced concrete core. The skins of blockwork are tied together using extra-long wall ties and theses walls eliminate the need for shuttering. The walls are constructed in limited vertical lifts to ensure that the concrete pressure does not push over the blockwork. Hollow blocks can also be used, but construction can be awkward and care is necessary. There are systems of dry laid hollow blocks which are very good and worthy of consideration.
A reinforced concrete wall is a shuttered reinforced concrete walls stem linked to a reinforced foundation. This wall type is usually adopted for major works where shutting is available and it is possible to re-use the shuttering for economy on subsequent concrete pours.
Gabion baskets are wire baskets filled with stone which are often seen supporting embankments at the sides of highways. These walls are quite bulky and a reasonable amount of room for construction is required, but this can very economical.
Timber crib walls consist of a framework of timber which is infilled with soil and the mass of the wall with the soil holds back the soil behind. The thickness of construction is determined by the nature of the soils and surrounding environment.
Concrete crib walls are similar to timber crib, but constructed with reinforced concrete sections instead of timber.