Geogrid-anchored sheet pile walls; a small-scale experimental and numerical study

The use of geogrids to anchor Sheet Pile Walls (SPW) is relatively new. A series of small-scale tests was performed to investigate the behaviour of geogrid-anchored SPWs subjected to strip footing surcharge loading. Particle Image Velocimetry (PIV) techniques were used to measure soil displacement and analyse the global failure mechanism and dominant soil-geogrid interaction mechanisms. One of the tests was duplicated in a test box that was eight times as wide, showing that the influence of the small width of the test box was acceptably small. A 2D finite element model (PLAXIS) was used to simulate the tests and there was a reasonable match with the test results. The position of the strip footing load, and the length and number of the geogrid anchors, proved to be key factors in determining the bearing capacity. The results provide new insights into the stabilising effect and the effective length of the geogrid anchors, in other words the length along which geogrid-soil friction is mobilised. Contrary to the Dutch design guidelines for reinforced soil walls and conventionally anchored sheet pile walls, the results showed that the geogrid provides resistance in the active zone under the strip footing surcharge loading.