What is foundation or Sub-Structure?
In any structure the lowest part is called foundation. In general cases, structures comprise two parts: upper part and lower part. The part lying above the ground surface is upper part where as the part buried below the ground surface is lower part. Being the portion above the ground surface, the upper part is called super-structure while the lower part, the sub structure or foundation. The foundation acts as an interface between the super-structure and that part lying under the soil. Therefore the foundation can be considered as a medium as it receives the load from the super-structure and transmits it to the sub-soil underneath.
Every structure whether it is a bridge, a building, a tower, a tunnel, a dam, a highway, a pipe line, an embankment, an irrigation canal, a hydraulic structure, an earth retaining structure, an underground power house etc should be built on soil, by soil, or into soil. As we are already aware of the fact that the soil is a multi-phase material having diversified physical as well as engineering property. Under the action of external loads, its behavior is very complex.
Engineers and architects during building some projects provide due emphasis to the aesthetics, design and construction of super structure and design of foundation, which is actually the most vital part of the project is given least importance. We can say, the design of foundation is given the treatment as that of a stepchild in a family. The reason behind the ill treatment of foundation is because of the fact that the foundation is the buried structure and cannot be seen directly like the superstructure. We realize the visible features of foundation distress only through the results of its inadequacy shown by the superstructure in the forms of cracks, tilts, distortion and sometimes the complete collapse of the structure itself. Due to these reasons it would not be improper to say that the design of foundation has no magnificence.
And, therefore the professionals responsible for the project often leave this unglamorous work of foundation design in the hands of other professionals who are not familiar with the performance of supporting soil under external load as well as the art of the foundation design. Since the expenses are borne by the owners, the professionals do not bother much about the cost. This unscientific trend has reflected its consequences in the form of distresses in many of the recently designed and constructed buildings. The negligence or lack of attention in the design of sub-structure (foundation) can be costly to the owners as well as the professionals involved. It can be very embarrassing and results in loss of investment, property and sometimes loss of human life as well. Thus, the foundation which is a vital part of any structure, shall be provided due importance for the establishment of a proper structure.