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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.

SUMMARYA finite element technique is developed for two-dimensional problems of dynamics of dam-water-foundation systems taking into account all interactions rigorously. Water-foundation interaction, which previous developments have only simulated, is considered by imposing proper conditions at the fluid-solid interface. Furthermore, the technique permits treatment of layered foundations. An application to a concrete gravity dam-water-foundation system is presented and discussed.

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