Dynamic Response of Intact Piles to Impulse Loads

Abstract

SUMMARYThe objective of this work was to evaluate the theoretical capabilities of the non-destructive impact-response method in estimating the length and cross-sectional area of intact piles. Three-dimensional (3-D) axisymmetric finite element models were developed to simulate the testing. The results obtained were compared to one-dimensional solutions to evaluate the importance of 3-D effects. Extensive parametric studies were then performed on piles without defects. In each parametric study, the results from the direct use of time histories of displacements or velocities, the mobility function and the Fourier transform of the recorded displacements (impact-echo method) were compared in order to assess their relative advantages and disadvantages. The effects of the relative stiffness of the surrounding soil to that of the pile and of the embedment depth were also investigated for all three methods. In a companion paper the use of these procedures to detect defects such as bulbs (increases in the cross-sectional area of the pile) or necks (decreases in area) is studied.

Time–frequency analyses of pile-integrity testing using wavelet transform

“…The numerical pile is assumed to be embedded 6 m in the soil. If the ratio of the pile's Young's modulus (E p ) to that of the surrounding soil (E s ) is 50:1 or larger, then the testing method can work clearly ( [7]). Herein, the ratios are assumed to be 500 and 1000 for pile P 500 and P 1000 , respectively, as illustrated in Table 2.…”

NDT of Piled Foundations: Data Processing with Artificial Neural Networks

“…As in previous work 12,13 , the pile-soil system has been modelled as a 2-D continuum with material properties assumed to be linear elastic with elements of the isoparametric type. Such assumptions have been shown to be justified for the case of small strain testing.…”

Analysis of Dynamic Stiffness of Bridge Cap‐Pile System

“…The velocity spectrum is divided by the force spectrum to determine the mobility or mechanical admittance spectrum [14], which helps provide more information than the traditional pulse echo method to identify defects near the top of the pile [15]. Some key information from the graph, such as the peak/mean mobility ratio, mobility, and damping, is widely used to evaluate the pile integrity and pile length [16][17][18][19]. Another important parameter from mobility spectrum is the dynamic stiffness.…”