Non-destructive inspection of ground anchors using guided wave propagation

Abstract

This paper deals with numerical and experimental investigations of specific problems of guided wave propagation in ground anchors, focussing on recognizing the phenomenon of the energy transfer between anchor components. Particular attention is paid to characteristic features of guided waves propagating in free and embedded parts of the tendon, at the interface between the tendon and the surrounding anchor body, as well as waves diffracted on the start of the anchor body. Anchors with variable lengths and diameters of the anchor body, as well as anchors with non-reflecting boundary conditions, are analysed numerically. Experimental measurements are conducted on laboratory models of ground anchors of different fixed lengths. The study shows that the detailed recognition of the phenomenon of the transfer of the wave energy between the tendon and the anchor body is crucial for the appropriate application of the guided wave propagation method for non-destructive inspection of ground anchors. The obtained results indicate that the three most important geometric parameters, i.e. the anchor body length, the free length of the tendon and the thickness of the anchor body, can be determined on the basis of wave propagation signals recorded at the free end of the anchor.