A recent mixed-use development along the River Liffey embankment in Newbridge required a 4.5-metre cantilever wall to hold back saturated glacial till. The site was tight, with a public walkway and a Victorian-era culvert within 2 metres of the excavation line. Standard solutions were off the table. We ran triaxial tests on undisturbed Shelby samples to capture the till's effective cohesion, then modelled the wall in PLAXIS 2D under drained and undrained conditions, factoring in the 0.09g design acceleration from the Irish National Annex to EN 1998-1. The wall was detailed with a shear key and a 600 mm gravel drain behind the stem, which kept pore pressures below the values assumed in the ULS check. When geometry or surcharge loads push beyond what a conventional gravity wall can handle, the anchors option provides a way to transfer tensile loads into competent limestone bedrock, a configuration we have used on several tight infill sites near Newbridge's town centre.
A retaining wall in Newbridge's glacial till demands more than a generic cross-section — it needs a site-specific groundwater model and a karst assessment before the first reinforcement bar is specified.
