The tensile capacity of bored piles in frictional soils

Three series of 10 piles each were installed in two different locations. The lengths of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The piles were tested to failure in axial uplift and the load-displacement relations were recorded. The results from the tests have been compared with theoretical values based on current design practice and the method proposed by Fleming et al. seems to produce the best match with the test results.