The foundation structure is used to transfer loads (from the building that is constructed on top of it) to the ground. In some cases, foundations also provide a smooth and stable building surface. If a foundation is not used or is poorly designed it can lead to soil ‘shear failure’, which in turn can lead to the damage or demolition of the building itself.
Potential Problems
There are several different problems that a foundation can encounter, and the foundation engineer must consider all of these issues during the design process. Differential settlement after construction (one area of soil built upon settles more than another area), for example, results in sagging, foundation cracks, and sometimes the collapse of buildings. Scour, caused by flowing water eroding soil and rock from around and underneath the foundation, can also lead to serious damage.
In cold climates, frost heave, permafrost, and soil moisture changes must also be considered. The swelling and shrinking of soil (known as ‘soil distortion’) caused by cold weather patterns or rapid changes in temperature between seasons is a common problem confronted by foundation engineers in the UK.
Solutions
Luckily, a correctly designed foundation should be able to withstand any of the above problems and ensure the stability and safety of the building or structure. The engineer will consider whether to employ a shallow foundation (spread-footing, mat-slab, or slab-on-grade foundations) or deep foundation (using piles, drilled shafts, caissons, or piers). Each alternative suits a specific soil and climate type, meaning that theoretically there should be a solution to every foundation problem.
Also, existing foundations can be rescued by the expertise of a well-trained and accredited engineer. If a foundation is deteriorating it can be stabilised and strengthened by the use of underpinning techniques, preventing a catastrophic failure of the building structure.