Abstract: It’s found that the compression of pile shares a high proportion of the overall settlement in overlength pile foundation. Assuming the pile foundation as a rigid body in the equivalent pier method is not appropriate. A method considering compressibility of pile is proposed to calculate the settlement of super-long pile foundation. By analyzing the existing test data of overlength piles, a fitting equation expressed by compressibility coefficient of rock-socketed pile shaft is given; and a coefficient of 0.5 for non-rock- socketed pile is obtained. The formulas for settling ratios of pile shaft and pile tip are deduced. Meanwhile, the Matlab program is realized. At last, considering compressibility of pile, a case study is presented to calculate the settlement of overlength pile foundation; and the calculated and measured results have good agreement.

Key words: settlement of overlength pile group, compressibility coefficient of pile shaft, displacement-coordination method, settling ratio of pile shaft, settling ratio of pile tip, load factor