SERVICE LOAD OF SHORT LARGE-DIAMETER BORED PILES

Field loading tests of 10 short nondisplacement piles are analyzed usi ng the writer's method of calculating the service load of long piles. The method is based on the analysis of over 200 field loading tests. A hyperbolic relation is assumed between the specific skin friction q(s ) or toe pressure q(t) and the slenderness L/D (length/diameter) of pi les. The assumption is affirmed statistically to be acceptable for lon g piles (since q(t) --> 0 for L/D --> 0). Using the method, an express ion is deduced relating the skin friction share of the total service l oad to the pile slenderness. This forms a simple and uniform basis of the calculation of service load of piles of different slenderness and of soils of different consistencies and densities. The calculated serv ice load of short piles was overestimated. This was explained by the t oe pressure having been reduced by the heavy disturbance of the soil e xperienced at the pile toe by boring.