Retaining walls are structures that hold back soil or rock from falling due to landslides caused by gravity or erosion. Watertight retaining walls (cofferdams) are employed in conjunction with an appropriate dewatering scheme to hold back water and clay in wet areas. In deep excavations, these walls have to withstand great lateral earth pressures and hydrostatic pressures caused by ground water. Depending on design requirements, several pile types and configurations are used to construct retention systems.
Closely spaced piles used to form retaining walls in areas where water inflows are not significant. Their main use is in clay soils and they may also be used to retain dry granular materials or fills. In water bearing granular soils, seepage is likely to occur in the gaps between the piles which can be prevented by grouting these gaps to form a watertight retaining wall.
