The increase of wave velocity with time in concrete piles

Abstract

Low-strain dynamic pile tests were performed on a number of engineering cases. Analysis of the relationship curves between pile-head velocity and time, and between modulus magnitude of mechanical admittance and frequency, shows that the dynamic wave velocity and pile-soil dynamic stiffness increased with time in the first month or so. The increase is attributed mainly to the enhancement of lateral constraints, corresponding to the thixotropy and consolidation of the surrounding soil. Comparison of the test results shows that the increase in wave velocity is consistent with that in pile-soil dynamic stiffness.