Caisson Wall

A caisson wall is an excavation support system constructed by vertically drilled holes to form an interlocking secant wall. A sequence of soldier piles and caisson fillers make up the shoring wall with the piles reinforced with steel beams and fillers left unreinforced and filled with low strength concrete. Piles are typically spaced on a two or three filler sequence. Depending on the excavation depth requirements, piles can be cantilevered or braced with walers, rakers, struts and/or tiebacks.

Advantages of caisson walls:

• Rigid shoring system
• Eliminates ground loss. Ideal for shoring adjacent to existing buildings and other sensitive infrastructure
• Can be installed in poor soils and below the water table
• Improved control of groundwater. Can be designed as a cut-off wall to retain water and reduce project dewatering requirements

Challenges associated with caisson walls:

• Drilling tolerances must be tight to ensure design interlock is maintained
• More costly than soldier piles and lagging/shotcrete shoring solutions due to higher material usage requirements and increased vertical drilling duration