This case involved an aparthotel that had been built as a terraced structure on the side of a hill. Substantial and sustained settlement had occurred over a period of time. This manifested itself in wide structural cracks, resulting in ingress of water into apartments.

Harrison Geotechnical was instructed to investigate the cause of the subsidence. We found that there was inadequate provision to minimise settlement and its effect in the design of both foundations and structure. The soils on which the building was constructed comprised principally heavily over-consolidated clay with a depth of desiccation of 6m. This means that this depth of clay is affected by seasonal changes in moisture content leading to continual swelling and shrinkage. The net effect of this with time was differential settlement, with the front, south-facing apartments settling the most.

The problem was exacerbated by inadequate structural detailing: the apartments were in effect a series of boxes arranged in a terrace on the hillside and there was no structural integrity between the various elements and thus the movement was not spread uniformly through the structure but rather manifesting itself in distinct major cracks.

We designed an underpinning scheme for development using a sophisticated piling system. However the budget for doing the work was prohibitively expensive and in the event the aparthotel was closed and the building de-commissioned to the considerable cost to the client.

Owing to the prevailing Maltese law, foreign experts could not give oral evidence in court, however Harrison Geotechnical’s written evidence was used in the ensuing case against the architect and engineer.