Geotechnical Engineering

DHARM

SHALLOW FOUNDATIONS 649

13. S.B. Sehgal: A Textbook of Soil Mechanics, Metropolitan Book House Pvt. Ltd., Delhi-6, 1967.


14. Shamsher Prakash and Gopal Ranjan: Problems in Soil Engineering, Sarita Prakashan, Meerut,
    India, 1976.


15. Shamsher Prakash, Gopal Ranjan and Swami Saran: Analysis and Design of Foundations and
    Earth-Retaining Structures, Sartia Prakashan, Meerut, India, 1979.


16. A.W. Skempton and L Bjerrum: A Contribution to Settlement Analysis of Foundations in Clay,
    Geotechnique, London, 1957.


17. W.C. Teng: A Study of Contact Pressure Against a Large Raft Foundation, Geotechnique, London,
    1949.


18. W.C. Teng: Foundation Design, Prentice Hall of India Pvt. Ltd., New Delhi, 1976.


19. K. Terzaghi and R.B. Peck: Soil Mechanics in Engineering Practice, John Wiley & Sons Inc., NY,
    USA, 1948.


20. K. Terzaghi: Evaluation of Coefficient of Subgrade Reaction, Geotechnique, London, 1955.

QUESTIONS AND PROBLEMS

15.1 (a) What is the function of a ‘foundation’?
(b) Write an explanatory note on the general types of foundations, with suitable sketches.
15.2 (a) What are the general consideration in the choice of the foundation type?
(b) How is the depth of the foundation determined?
15.3 (a) How is the settlement of footings estimated?
(b) Write a note on the methods of proportioning of footings for equal settlement.
15.4 (a) How are eccentrically loaded footings designed?
(b) Write a note on the ‘useful width concept’.
15.5 (a) Explain the circumstances under which a strap footing is used.
(b) What is the basis for design of strap footings?
15.6 (a) What are the conditions under which combined footings are used?
(b) When is a trapezoidal combined footing preferred to as rectangular one?
Explain how it is proportioned.
15.7 (a) What is a ‘raft foundation’? When is it preferred?
(b) Explain the concept of floating foundation applied to a raft.
15.8 (a) Explain the conventional rigid approach to the design of a raft foundation.
(b) What is the coefficient of subgrade reaction? On what factors does it depend?
15.9 (a) Explain how a foundation may be designed when a dense stratum overlies a loose one.
(b) How is a foundation designed when soft and stiff layers alternate at a site?
15.10 (a) A building is supported symmetrically on nine columns, spaced at 4.5 m c/c.
At the chosen depth of 2 m, the allowable bearing capacity is 300 kN/m^2 ; γ = 18 kN/m^3.
(b) The column loads are as given below:
Column No. 123456789
DL (KN) 200 350 250 270 500 350 150 350 350
LL (kN) 200 400 200 270 650 350 120 300 180
Proportion the footings for uniform pressure and for equal settlement.