Applicability of the calculation formula of dynamic bearing capacity and the dynamic load test for the small diameter steel pipe pile constructed by rotary penetration

摘要

The applicability of the dynamic load test and the calculation formula of dynamic bearing capacity was examined in detail compared with the results of the static axial compressive loading test only for the small diameter steel pipe pile constructed by rotary penetration. In this dynamic load test set so that the impact energy does not exceed the buckling stress of the small diameter steel pipe pile, the characteristics such as the yield and elastic return of the ground in the static axial compressive loading test were largely reproduced, and the upper limit of the estimated ultimate bearing capacity generally satisfied the target for this pile. The quantities of penetration and rebound in the dynamic load test were affected by the ground strength of the tip and the peripheral of the pile, the product of the impact energy and the penetration quantity showed a relation inversely proportional to the ultimate bearing capacity, and the product of the impact energy and rebound quantity showed a direct relationship with the ultimate bearing capacity. These were most consistent with the Hiley formula induction process. In addition, a high correlation was obtained between the dynamic ultimate bearing capacity by Hiley formula and the static ultimate bearing capacity by the static axial compression loading test. Therefore the applicability of Hiley formula and also effectiveness to the cases remaining high of the design length or the pre-drilling were confirmed.