Compressible Inclusion Against Expansive Soil

Another application for utilizing EPS geofoam is to use it as a compressible inclusion adjacent to a structural element when it is in contact with expansive soil (Horvath 1996). Expansive soils or swelling soils are those soils that have the ten-dency to increase in volume when water is available and to decrease in volume if wa-ter is removed (Ranjan and Rao, 1993). Figure 2-17 shows part of a structure on pile foundations. The compressible inclusion EPS geofoam is utilized below the structural slab. Upon soil heave EPS geofoam compresses according to its own stress strain re-lation as shown in figure 2-3. The stresses on the structural slab will be limited to a specified value depending on the density of the EPS geofoam. The geofoam will also act as a form for the slab.

On the Channel Tunnel project in England EPS geofoam was utilized as a compressible inclusion (Horvath, 1995a). The purpose of utilizing EPS geofoam was to reduce heave pressure below the floor system of the channel tunnel.