What is the swelling magnitude when a foundation is constructed on wetter soils?

The swelling magnitude when a foundation is constructed on wetter soils is most accurately represented by high magnitude with low shrinkage. In soils, particularly clay soils, water content plays a crucial role in their physical behavior. When clay soils are saturated or wetter, they tend to swell significantly because the water molecules enter the spaces between clay particles, causing them to push apart. This results in a high swelling potential.

Simultaneously, if these wet soils eventually dry out, they can experience shrinkage. However, when the soil is initially saturated, the situation is described more by the swelling from the moisture rather than shrinkage, especially if the soil is kept wet during construction or if the foundation induces additional moisture into the soil.

Therefore, in the context of the given situation, while there may be some shrinkage, the dominant behavior of wet soils is to swell, reflecting a high swelling magnitude with potentially low or minimal shrinkage, depending on the moisture condition maintained during and after construction.