All the civil engineering structures whether buildings, dams, bridges, etc. are built on soils. A base is required to transmit the load of the structures on a large area of soil. The base of the structure should be designed so that the ground below will not fail in the shear nor will there be an excessive settlement of the structure. The conventional method of foundation design is based on the concept of load capacity. The soil is considered by the engineer as a complex material produced by the weathering of solid rock. The soil is the most important material used for the construction of civil engineering structures. Among all the parameters, the load capacity of the soil to support the load over unit area important. There are several methods to calculate the soil carrying capacity presented by the specialist. The main factors that influence the ultimate load capacities are the type of soil, the foundation width, the weight of the soil in the cutting area and the surcharge. Structural rigidity and contact voltage distribution do not greatly influence the load capacity. The analysis of the load capacity assumes a uniform contact pressure between the foundation and the underlying soil. With other factors unchanged, the type of soil failure, the depth of foundation and the effect of groundwater table control the bearing capacity of the soil.
When a soil is stressed due to loading, it tends to deform. The resistance to soil deformation depends on factors such as water content, bulk density, internal friction angle and the way the load is applied to the ground. The maximum load per unit area that the earth or rock can transport without yielding or moving is called bearing soil capacity. Soil properties, such as cut resistance, density, permeability, etc., affect the load capacity of the soil, dense sand will have more load capacity than loose sand as a unit