PILES AND PILE CAPS
Piles are commonly used when the soil immediately beneath a structure’s spread footing cannot bear its weight. They are also used to transfer loads to firmer strata located deeper underground or to protect against soil that is affected by seasonal changes. The pile’s bearing capacity, which is the amount of weight it can carry, is made up of two components: the end bearing capacity and the skin friction capacity between the pile’s peripheral area and the surrounding soil. However, the contribution of each component varies significantly depending on the soil conditions. For instance, sandy soils have lower skin friction resistance than clayey soils. Typically, the load to be supported is greater than what a single pile can bear, necessitating the use of a group of similar piles. The group is then capped with a spread footing or cap, which distributes the load evenly across all piles. In some cases, it may be more cost-effective to create a piled raft, which is formed by using a single large cap instead of individual caps when dealing with many closely spaced piles.
