Rigid Inclusions / CMC / Grout Columns
Rigid inclusions contain elements that are slender, often cylindrical in shape, mechanically continuous and typically vertical. They are laid out according to a regular mesh pattern, which must be adapted both to the nature and geometry of applied loads and to soil conditions.
Inclusion placement, combined with a load transfer platform, ultimately leads to a composite or reinforced soil volume, which tends to be stronger and less deformable than the initial soil volume, allowing the structure to lay on a shallow foundation. The general concept of the technique is the combination of an array of vertical rigid columns and a granular mattress (load transfer layer) so that loading from an embankment or slab is transferred to a deep bearing stratum.
The rigid inclusion system may be applied to all types of soil conditions. In practice however, its economic benefit remains confined to soft or medium soils, which are most often compressible. Generally, all materials containing organic matter require special attention due to the fact that they are subjected to secondary compression settlements.
The most widespread applications relate mainly to the limits of conventional soil improvement techniques because of their inability to guarantee the necessary settlement criteria or their requirement of a minimum quality threshold for the surrounding soil.
- This technique is cost effective for heavier loads and stringent settlement requirements which are not achievable by conventional soil improvement techniques.
- A wide range of techniques may be used to install inclusions.
- Less or no spoil based on the installation technique being applied.
- Faster and economical compared to piles.
- There is no connection between columns and the structure above them, which generally simplifies structural design.
- The technique provides good seismic performance when properly designed