The loud of the is ultimately coming on the soil and hence it is of most important to know the strength and behavior of soil. the term bearing power or capacity of the soil is used to indicate the maximum load per unit area which the soil will resist safely without displacement. the bearing capacity of the soil used for the design of foundation [i.e. for determining the dimensions of the foundation ]. The soil has a tendency to behave in a complex manner when loaded and it gets deformed when stressed due to the loading. the resistance of the soil to such deformation will depend, upon the physical properties of the soil such as shape, size, density, surface texture, voids. Frictional resistance, cohesion, and moisture retaining capacity.
Ultimate Bearing Capacity:- The ultimate bearing capacity is defined as the maximum load per unit area that the soil below foundation can carry before failing in shear.
Safe Bearing Capacity:- The term is used to denote the maximum load per unit area that the soil can resist safely without displacement.
This is obtained by dividing the ultimate bearing capacity by a certain factor of safety and is the value which is used in the design of foundation. The factor of safety normally varies from 2 to 3.
Allowable Bearing Pressure:- It is the net loading intensity at which neither the soil fails in shear nor there is excessive settlement detrimental to the structure in question. The allowable bearing pressure thus depends both on the subsoil and the type of building concerned and is generally less than and never exceeds the safe bearing capacity.