Rigid inclusions are used to improve the overall strength and stiffness or soft of loose soils. Whilst not intended to carry full structural loads the rigid inclusions are designed to reduce stresses in the weaker soils thereby improving the performance of the ground in terms of settlement and overall strength. The rigid inclusions can be formed by a number of methods including conventional piling techniques such as CFA piling, driven piling or displacement auger piling.
Whilst requiring more detailed design input compared to conventional deep foundations, rigid inclusions can offer significant cost and programme advantages compared to deep foundations. This is due to reduced depth and number of piles compared to conventional piles and generally reduced structural strength of the inclusions compared to conventional piles.
Rigid inclusions are often constructed in combination with a rigid surface slab, similar to a piled raft, or a load transfer platform comprising engineered granular material. The method can be applied to building developments, infrastructure projects or land development.
The design of the rigid inclusions and load transfer platform requires specialist knowledge of soil structure interaction and commonly adopts the use of 3D finite element modelling such as Plaxis 3D. The staff of CMW Geosciences have been involved in the design and construction of several schemes incorporating rigid inclusions and can provide advice from concept design through to detailed design, construction supervision and performance monitoring.