Secant Pile Walls:
Secant pile walls can be used for temporary rigid support of excavation or to form permanent earth retention systems. This technique is suited for dense, urban environments. Walls are constructed by the sequenced drilling and construction of overlapping, reinforced concrete piles. Although more costly than sheeted excavation support, this system offers greater alignment flexibility and increased wall stiffness and can be drilled through bouldery or cobbly soils.
Tangent Pile Walls
Tangent pile wall construction is similar to that used for secant pile walls except that the piles are designed to touch rather than overlap. Since tangent pile wall construction eliminates the need to drill through previously placed wall elements, construction is faster. This type of system is typically not used where a groundwater cut-off is required.