Dr. S. K. Prasad
Professor of Civil Engineering
S. J. College of Engineering, Mysore
7.0 Syllabus
1. Definition of ultimate, net and safe bearing capacities, Allowable bearing pressure 2. Terzaghi’s and Brinch Hansen’s bearing capacity equations – Assumptions and Limitations 3. Bearing capacity of footings subjected to eccentric loading 4. Effect of ground water table on bearing capacity 5. Plate load test, Standard Penetration Test, Cone Penetration Test (8 Hours)
7.1 Definitions
Bearing capacity is the power of foundation soil to hold the forces from the superstructure without undergoing shear failure or excessive settlement. Foundation soil is that portion of ground which is subjected to additional stresses when foundation and superstructure are constructed on the ground. The following are a few important terminologies related to bearing capacity of soil.
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|Fig. 7.1 : Main components of a structure including soil |
7.1.1 Ultimate Bearing Capacity (qf) : It is the maximum pressure that a foundation soil can withstand without undergoing shear failure.
7.1.2 Net ultimate Bearing Capacity (qn) : It is the maximum extra pressure (in addition to initial overburden pressure) that a foundation soil can withstand without undergoing shear failure. qn = qf - qo
Here, qo represents the overburden pressure at foundation level and is equal to үD for level ground without surcharge where ү is the unit weight of soil and D is the depth to foundation bottom from Ground Level.
7.1.3 Safe Bearing Capacity (qs) : It is the safe extra load the