Factor affecting bearing capacity

Factor affecting bearing capacity?

The bearing capacity of soil is influenced by various factors-

-The physical features of foundation

   Type of foundation

   Size of foundation

   Depth of foundation and

   Shape of foundation significantly affects the bearing capacity

-The amount of total and differential settlement is one of the main controlling factors for the

   bearing capacity of the soil.

-The relative density in the case of granular soil and consistency in the case of cohesive soil play a               decisive role in influencing the bearing capacity.

-The physical as well as engineering properties of soils such as

  Density

  Cohesion and friction

  Position of water table

  Original stresses are the other factors governing the soil bearing capacity.

Bearing Capacity of Granular (Cohesionless) Soils

In the case of sands the cohesion, c is absent. Hence, for sands, the bearing capacity equation is of the form:

 

---------------------------(1)

The Equation (1) shows that the bearing capacity in sands increases as the depth and width of foundation and soil unit weight, increase.

The presence of water table at the surface or at the base of the foundation reduces the bearing capacity significantly.

Bearing Capacity of Cohesive Soils

In the case of cohesive soils the angle of internal friction  is zero. Accordingly,  and Nq = 1. Hence, for clays, the bearing capacity equation is of the form:

  

-----------------------------------------------------(2)

The Equation (2) shows that the bearing capacity in cohesive soil increases as the depth of foundation and soil unit weight, increase.

The presence of water table at the surface or at the base of the foundation reduces the bearing capacity significantly.

The bearing capacity is independent of the width of foundation.