Rigid Inclusions

SCS Drill Rig and PumpRigid Inclusions (used as Displacement Columns for structural load transfer or as Controlled Stiffness Columns (CSC's) for ground improvement) are a quiet, vibration free and economical foundation or ground improvement element that produces virtually no spoil arising. The process is ideally suited to soft soils overlying stiff bearing strata and for contaminated sites where handling excavated spoil is environmentally unacceptable. CSC’s are sometimes known as Concrete Injected Columns (CIC) or Controlled Modulus Columns (CMC). CSC’s are often used as an economical alternative to Screw piles, or Timber Piles. When combined with appropriate ground slab design, very economical solutions can be provided for warehouses and other moderately loaded building structures. CSC’s are also used in ground improvement on road and rail infrastructure projects (typically between piled bridge abutments and untreated road pavements).

When fully reinforced they can transfer structural loads. When appropriately designed they can improve the bearing capacity of a wider soil block and are typically used in this manner beneath road or railway embankments.

CSC Ground Improvement

CSCs are not intended to directly support the loads imposed by a structure, but to improve the global response of the soil in order to control settlement. The dimensions, spacing, and composition of the CSCs are based upon the development of an optimal combination of support from the columns and the surrounding soil to limit settlements for the project within the allowable range, and to obtain the required value for the equivalent composite deformation modulus of the improved soil.

Two different techniques can be used to construct Rigid Inclusions', either a Full Displacement Auger or a Vibrated Steel Tube. The full displacement auger construction principal is similar to CFA piles however a specially designed displacement auger is used in conjunction with a high torque drill rig to displace the soil and facilitate placement of concrete through the drill head stem to construct columns in the ground.

A typical displacement auger is shown in the photo adjacent.

During the drilling process the ground is loosened by the auger teeth and transported through the auger flights until it reaches the widest point of the displacement body. Here, the soil is pushed in the adjacent ground, compacting the surrounding soil and, usually, improving the skin friction of the pile.
Concrete placement and reinforcement cage installation are carried out in the same manner as for CFA piles.
Typical diameters for this pile type are 360mm, 450mm and 520mm. Pile lengths can be up to 30m.

Piling Contractors offers design and construct or construct only solutions and will carry out in-house on site verification through appropriate load tests.