When we design the foundation of a building structure we have to first find out the loading on the column in the basement. That means the load carried to the foundation through the column from the superstructure it self. For this we can use a computer package such as Etabs, Sap 2000, Prokon, Midas Gen or Staad pro. We will discuss about the handling these software's for foundation loads later.
Then what we need to design the foundation is the bearing capacity of the subsurface soil. For that we will usually have a value like 150kN/m2. Guessing or deciding this value is needed testing the soil or site soil strata investigation method. There are three major methods for finding out the bearing capacity of the soil. They are, Test pit method, Macking prob tetst and SPT method.
(1). Test pit method : We have to dig a 1mx1mx1m pit in the ground surface and we can get in to the pit and we can visually observe the soil strata in it. From that we can see weather the soil condition is stiff or weather several types of soil layers available in the subsurface or are they loos or are they sandy or clay or laterite. We call a single word for this. It is "Stratification" This method is usually used for deciding the bearing capacity for single or double story house constructions on surfaces with no or less issues. If the soil is badly marshy, we have to go for an another costly method although it's a house construction.
