We offer a variety of bored pile retaining walls when provision for temporary and permanent support for basement excavations is required. We have the expertise and technology to ensure that ground movements are controlled and an economic solution is found.
The most common methods, secant and contiguous walls are discussed on this page. However further guidance and explanation of different techniques can be found in CIRIA guide C580.
Secant piles are installed by overlapping reinforced male piles and female piles which are installed with a low strength gain concrete. They are adopted to restrict groundwater and fines inflow with retained heights of up to 8m common. Greater excavation depths may be achieved. However the geological and hydrological conditions need to be considered along with installation tolerances when determining the suitability of the application.
Contrary to their name, contiguous piles are actually installed with a gap of 100-200mm per pile. This means that the wall is not water or fines tight. However where the conditions allow, such as in cohesive soils, it can be the most economic form of retaining wall.
The choice of construction technique, CFA or Rotary, is dependent upon soil type but can range from 300-1200mm diameter.
This can provide retained heights of up to 15m with propping and 10m in a cantilever situation.