Three-dimensional propagation of waves in piles during low-strain integrity tests

Abstract

In this note the concept of discretising the pile into virtual parts is introduced in order to derive an analytical solution that describes three-dimensional propagation of waves in piles during low-strain integrity tests, considering both vertical and radial pile displacements. The effect of transverse wave propagation on the results is quantified by comparing the proposed solution against a previously published method in which only vertical displacement was considered, results of dynamic numerical analyses, as well as the classical one-dimensional solution. Using the obtained waveforms, an attempt is made to identify and describe the mechanisms of three-dimensional propagation of longitudinal waves in piles, and how these may affect the interpretation of low-strain integrity tests.

Closed‐form formulation of vertical dynamic response of single floating piles in homogeneous viscoelastic soil

“…This so-called plane strain model has been particularly popular among researchers working on soil-pile interaction problems, and has been adopted in a number of subsequent studies. [16][17][18][19][20][21] However, an important drawback of the plane strain model is that it does not predict the formation and propagation of standing waves in the soil surrounding the pile. As a result, mathematical models based on Novak's work cannot provide accurate predictions of the dynamic response of piles in the low frequency range, and this limit their applicability to problems involving relatively high-frequency loads.…”

“…A different approach that does not suffer from this shortcoming has been proposed by Novak and his co‐workers, 14,15 in which the soil around the pile is modelled explicitly with a series of independent thin layers, that extend to infinity in the radial direction. This so‐called plane strain model has been particularly popular among researchers working on soil‐pile interaction problems, and has been adopted in a number of subsequent studies 16–21 . However, an important drawback of the plane strain model is that it does not predict the formation and propagation of standing waves in the soil surrounding the pile.…”

Torsional Low-Strain Test for Nondestructive Integrity Examination of Existing High-Pile Foundation

“…High-frequency interferences often occur during the tests of large diameter piles, which are not revealed by the one-dimensional rod theory. The high-frequency interference can be addressed by simulating the soil and pile as three-dimensional continuum media [ 20 , 21 ]. However, due to the massive computation involved in rigorous 3D continuum models, digital signal filters (e.g., Savitzky–Golay) are preferred by engineers.…”

Analytical solution for distributed torsional low strain integrity test for pipe pile

“…[5][6][7][8][9][10] When conducting the LSITs, the elastic waves would propagate in both radial and circumferential directions not only in the soil but also inside the pile body. [11][12][13] Zheng et al 14,15 proposed an analytical solution for the LSITs which can take the propagation of elastic waves in the radial direction into consideration. Liu et al 16,17 investigated the circumferential propagation of elastic waves in pipe pile and proposed the velocity stack method to eliminate the circumferential wave influence.…”

“…When conducting the LSITs, the elastic waves would propagate in both radial and circumferential directions not only in the soil but also inside the pile body 11–13 . Zheng et al 14,15 . proposed an analytical solution for the LSITs which can take the propagation of elastic waves in the radial direction into consideration.…”