Foundations – Types of foundations
Foundations are commonly well known as substructures that are positioned below the ground level and they transfer the structural load to the ground. Foundation of a building as the name implies is the starting of a building construction on site really. Types of building, nature of soil and environmental conditions are the major determinant of type of foundation. Choosing a kind of foundation depends on, ground conditions, groundwater conditions, site – the environment (the buildings nearby) and structure of our building. Foundations should be fulfill the structural requirements such as safe, be able to carry the load of the building and constructional requirements such as schedule, minimal resources, minimal cost.
Shallow foundations are applicable where the soil surface is firm and strong enough to carry the structural load. Most of the shallow foundations are lies within a depth of 3m and constructed near to the finished earth surface. In shallow foundation mostly, the depth of the foundation is less than the width of the foundation. Shallow foundations are economy, easy and cheaper in the construction sector. These types of foundations are applicable for structures with limited weight and they are not able to withstand for heavyweight structures. The following types of foundation are considered in shallow foundation.
Isolated spread footing
Deep foundations are used where the soil bearing capacity near the earth surface is too low. Here, the structural load could transfer through long, slender material to the deep where the strong soil layer is available. The depth normally exists greater than three meters from the ground level that is greater than the depth of shallow foundations. Although the deep foundations are more expensive and suitable for complex construction process they are most effective to carry a huge structural load. When compare to shallow foundation, deep foundation need enough time period, skilled labours, heavy machinery. The deep foundation could be classified as below.