Centrifuge Modeling of the Nondestructive Testing of Soil Anchorages

Ground reinforcement anchorages are a means of ensuring the stability of a wide range of structures and retaining walls. The performance of an individual anchorage depends on the tensile load that the anchorage is carrying but this will change over the anchorage’s life span, so it is therefore necessary to have some way of measuring this load. A nondestructive technique, ground anchorage integrity testing (GRANIT), in which impulse responses of anchorages are determined to evaluate whether load transfer is maintained, has previously been developed for anchorages in rock. This research examines the possibility of extending this to soil anchorage systems. In this work, implementation of a model nondestructive testing system is tested using a geotechnical centrifuge. Load distributions along centrifuge model anchorages are measured and found to reduce gradually within the fixed length, as is the case with rock. Anchorage frequency responses to impulse loads are then evaluated to validate the consistency of the results obtained. Various anchorage inclinations and fixed lengths are also investigated, showing that inclined anchorages contain a greater range of frequencies in their signature response. The practical importance of these results is that nondestructive testing may be usable for anchorages in soil as well as anchorages in rock. Further investigation is necessary to refine the relationship between anchorage load and response frequencies. This may be accomplished using centrifuge modeling.