A warehouse extension planned near the old shipyards on Queen’s Island ran into a problem that many developers in Belfast face when they first look at the borehole logs. The upper three metres showed loose silty sand overlying the Antrim Clay, and the water table sat barely a metre below the pavement. The structural engineer flagged seismic ground failure as a design concern that had not been accounted for in the initial foundation concept. In our experience, this scenario is far from rare. Belfast’s post-glacial stratigraphy — with sequences of soft estuarine alluvium, buried peat lenses, and loose granular fills across the Lagan Valley — creates exactly the conditions where a CPT test can deliver the cone resistance and pore pressure profiles needed to run a reliable liquefaction potential index, and a MASW survey provides the shear wave velocity data that feed directly into the simplified procedure under BS EN 1998-5.
In Belfast, the difference between a site that passes the liquefaction trigger check and one that requires ground treatment can be less than two metres of stratigraphy.
