This paper presents the test data of field static loading tests of overlength friction piles. The analysis of the data shows that the load transfer performance of overlength piles is similar to that of end-bearing friction piles. The ultimate side soil resistance from the depth of l/3 pile length beneath the ground surface to l/6 pile length is much higher than those recommended by the Specifications

which indicates that the side resistance is strengthened. However

the ultimate side resistance of other parts is in accordance with Specifications. And the base grouting can not only improve the soil bearing capacity under the piles

but also enhance in side soil resistance. Based on the analysis of the performance of overlength pile

a simplified method to calculate the ultimate load bearing capacity of single pile is suggested

which is validated by some pile case.