Raft Foundations Design and Analysis with a Practical Approach
In 1957, when the author was a student of Civil Engineering at the Indian Institute of Technology, Kharagpur, the first institute of national importance, one of his professors of Civil Engineering at his first lecture in the class said: "Civil Engineering is 50% common sense but common sense is that sense which is quite uncommon. " After 34 years of experience in Civil Engineering construction and design, the author only wonders how true the statement of his Professor was and how much more it is true in case of foundation engineering.
1.1 Foundation engineering has been practised as an art, without help of science, since time immemorial upto 1920 when it had achieved a considerable amount of refinement. It was in the earlier 1920s that a concerted ! effort was made to study and undentand the physical laks governing the behaviour of sub surface materials, \ i.e.. soil from which foundations derived their support and on whose behaviour its own behaviour depends.
This is the time when study of soil mechanics was started and it was in 1919 when Karl Terzaghi, popularly known as 'father of soil mechanics', made successful attempt to explain the phenomenon of settlement oti a scientific basis. Though study of soil mechanics has provided us with new techniques for selecting appropriate
type of foundation and predicting the behaviour of completed structures, it has not been able to decrease the importance of the accumulated experience of the ages. Amount of uncertainty and degree of variation in the properties of soil and number of parameters on which performance of a foundation depends, make exact solution impractical, if not impossible. With so much of advancement in science and computer application,
structural design is still defined as: