WHY IS BloCS-Net NEEDED?

A medieval breakwater with blockwork crownwall (Israel)

Around the UK and the Mediterranean, there are many coastal defence and harbour structures (seawalls, harbour walls, breakwaters) constructed of natural stone blocks. Some such structures use unshaped stone as quarried, others use shaped stone blocks.  Later structures used concrete blocks.  These structures were generally constructed to form harbours in the 18th and 19th century, and are now most often found in older / smaller ports and/or protecting coastal conurbations.

At some sites, the structures are in relatively good repair, but in many other these structures have suffered deterioration or significant damage.  In UK and in Italy, these historic structures often support important infrastructure, but often with little any explicit understanding of the importance of the structure. Worse, repair or rehabilitation of these structures is severely hampered by an almost complete lack of information on the mechanisms of failure.  A recent report in the UK for CIRIA identified no method to predict the effects of wave attack.  The most recent research led by HR Wallingford with Belfast and Sheffield has identified some possible mechanisms for blockwork movement, but has not yet clarified the importance of different mechanisms.  The most recent research studies within the leading EU research project on vertical breakwaters PROVERBS has not been able to identify any new guidance on suction / differential pressures on blockwork in vertical walls. It is clear that the fundamental modus operandi of such structures under wave attack is often misunderstood, and that some repairs completed in recent years are very likely to cause significant harm in the future. Without a more complete understanding of the mechanism or mechanisms responsible for the damage to and failure of these structures, the costs of repair or replacement can only be expected to escalate as the structures continue to age.

An understanding of the failures can be gained only from a combination of careful analysis of historical failure records, field data, new hydraulic models tests, and physical and numerical modelling of the detail of failure initiation mechanisms such as pressure propagation in cracks.

BloCSnet intends to synthesise the knowledge and skills of its members in order to develop a focussed research strategy in this field. The longer term aim of the team is to analyse the failure mechanisms, and facilitate the development and then dissemination of guidance on how these old structures work, how they should be analysed, and what methods should be used in their repair and rehabilitation.

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