There are several types of foundations used in building construction. The purpose of a foundation is to secure a building in place and transfer building loads into the ground. Commonly, houses are designed using shallow foundations. Before construction, the soil must be analyzed for load bearing capacity. If a soil strata analysis is completed and soil is determined to be too loose or incapable of holding proper building weight without sinking, a deep foundation will be used.
Deep foundations are required when soil and superficial ground content is not stable or thick enough to support heavy loads. Deep foundations are achieved by forcing vertical structure components several feet below the ground’s surface. The depth of the foundation is decided by how far stable soil lies beneath the ground surface.
Pile foundations are generally required to maintain safety in multi-story buildings. In addition, deep foundations in southern or coastal areas like Louisiana are necessary to gain stability despite a high water, silt, and loose clay ground content. In contrast, bedrock provides the most stable and safe building foundation. Pile foundations work to emulate a rock platform to provide a sturdy base.
Any raised structure will also require a pile foundation due to the concentration of building forces over a small area. The load bearing capacity of a pile depends on soil and structural capacity of the material from which the pile was made. Pile foundations also provide a reinforcement against seismic activity and wind forces.
Pile driving is a method of deep foundation application. Piles can be fabricated from concrete, timber, or steel. Piles can also be constructed of a mix of steel and concrete, called composite piles. Piles can take the shape of capped columns or form full underground wall-like support. Piles may be brought to the site and forcefully placed, or holes can be drilled into the ground which forms a cavity that can then be filled with concrete. This method is called in-situ piling or augercast piling. Basement walls are also considered a form of piling.
Piles can gain structural ability by placement friction. When physical piles are driven into the ground, they become stronger by the friction created when they are placed into the ground. Pile driving causes resistance between the pile and surrounding earth which creates an optimal foundation for further construction.