Need for soil test / soil exploration

Soil exploration (soil test) is necessary for foundation design because:

1. It finds the type, thickness and sequence of soil layers and the depth of rock.
2. It gives the bearing capacity of soil, which decides the size and type of foundation.
3. It allows the probable settlement (total and differential) to be estimated, so the design is safe.
4. It locates the water table, which affects excavation, bearing capacity and dewatering.
5. It finds problem soils such as black cotton soil, peat, fill or liquefiable sand.
6. It helps to choose between shallow and deep foundations, or ground improvement.
7. It gives information for the economy and safety of the building, preventing failure and damage, and avoiding over-design.