Soldier piles, are steel wide flange H-beam piles spaced 1 to 3 meters apart. They are driven into the ground prior to excavation by a vibratory or impact hammer or may be installed in drilled shafts and backfilled with concrete. Their main purpose is to provide permanent or temporary shoring for vertical excavation.
After insertion into the ground, the area between each two piles is excavated and timber, steel or pre-cast reinforced concrete panel lagging is inserted between the H-pile flanges as the soil is excavated in stages downward. The void space behind the lagging is then backfilled and compacted. Lateral earth pressures are transferred from the lagging onto the soldier piles. In high water table conditions, an extensive dewatering scheme is required with this type of retention system.