EMPIRICAL EQUATIONS BASED ON SPT VALUES FOR FOOTINGS ON COHESIONLESS SOILS.

Footings on granular soils are sometimes proportioned using empirical relationships. Teng (1969)
proposed an equation for a settlement of 25 mm based on the curves developed by Terzaghi and
Peck (1948). The modified form of the equation is


Meyerhof (1956) proposed the following equations which are slightly different from that of Teng



Experimental results indicate that the equations presented by Teng and Meyerhof are too conservative.

Bowles ( 1 996) proposes an approximate increase of 50 percent over that of Meyerhof which can also be applied to Teng's equations. Modified equations of Teng and Meyerhof are,

Teng's equation (modified),


If the tolerable settlement is greater than 25 mm, the safe bearing pressure computed by the above equations can be increased linearly as,


where q's = net safe bearing pressure for a settlement S'mm, qs = net safe bearing pressure for a settlement of 25 mm.

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