Portlaoise sits on a varied glacial geology, with compact lodgement tills overlying the Waulsortian limestone that defines much of the Laois basin. The water table here often rises within 2 to 3 metres of the surface during the wet months, which directly impacts the bond stress achievable in a grouted anchor. We design both active and passive restraint systems to manage lateral earth pressures in these mixed ground conditions. Temporary excavation support for the ongoing Portlaoise town centre redevelopment frequently demands a combination of pre-stressed active anchors and passive dowels to limit movement in adjacent structures. Our approach integrates site-specific friction angles from direct shear tests with the design methodology in IS EN 1997-1:2004, ensuring that each anchor tendon is sized for the long-term drained parameters of the local boulder clay.
In Portlaoise's compact till, a correctly tensioned active anchor transfers load beyond the active wedge, keeping urban excavations stable without oversized propping.
