Research on the Relationship between the Dynamic Stiffness and Pile Bearing Capacity

Abstract

The previous researches on the mechanical impedance method for pile testing mostly only stay on the basis of low strain. The method of calculating the pile bearing capacity has been controversial because the impact force is relatively small. However, a large amount of engineering practice data shows that the dynamic stiffness is closely related to the pile bearing capacity, and it is not advisable to negate it completely. A certain relative displacement is generated between the pile and the soil because the impact force is large enough during the high strain dynamic testing. At this time, the soil around the pile has entered the plastic deformation stage, and side resistance and end resistance have been fully stimulated. It is very valuable to explore the relationship between dynamic stiffness and the bearing capacity under this background. This paper discusses the relationship between the dynamic stiffness and the maximum impact force and the measured bearing capacity based on the measured data of high strain dynamic testing under the same geological conditions, pile length and pile diameters of the same project. The results show that the bearing capacity is positively correlated with the dynamic stiffness; the greater the dynamic stiffness, the greater the corresponding bearing capacity. The pile bearing capacity can be estimated by the measured dynamic stiffness value when the curve of dynamic testing is poor and the traditional mechanical impedance method can be used for the auxiliary analysis of high strain dynamic testing.