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Rigid Inclusions (Controlled Stiffness Columns)

Rigid inclusions is a ground improvement technique that transfers loads through weak strata to a firm underlying stratum using high modulus, controlled stiffness columns. A bottom-feed mandrel with a top-mounted vibrator is advanced through the weak strata to the underlying firm stratum. Granular bearing soils are densified by displacement. Concrete is then pumped through the mandrel, which opens as it is raised. The mandrel may be raised and lowered several times within the bearing depth to construct an expanded base if required by the design. The mandrel is then extracted while a positive concrete head is maintained. The concrete fills the void created by the mandrel during extraction, and terminates in an upper strong stratum or is subsequently overlain by an engineered relieving platform. The improved performance results from the reinforcement of the compressible strata with the high modulus columns. The technique has been used to increase allowable bearing pressure and decrease settlement for planned structures, embankments and tanks.

Contact your local Hayward Baker office for more information.

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