Rock Bag JIP Phase 2. Partners sought.

The Rock Bag JIP is about understanding the stability, performance and scour performance of rock bags on erodible seabed. The objective is to enhance understanding of how rock bags can be utilized as a supplementary stabilization method for subsea cables and Cable Protection Systems (CPS). With currently seven participants (Bluemont Australia, CRP, DEME, Nexans, JDN, Ridgeway Rockbags®, TenneT, Van Oord), the JIP would welcome the addition of further participants. Please contact AOE if you would like further information on this JIP, or on how to join it.

Phase 1 has already completed, and phase 2 meeting was held in December 2024. The meeting was attended by ten representatives of the eight participating sponsors across UK and Europe, as well as five representatives from Aurora Offshore Engineering (AOE) in Western Australia. The participants were updated on the dry testing scope which was recently completed. The first stage of wet testing, which will involve consideration of rock bags (also referred to as Filter Units) on erodible seabed was also discussed in detail.

The dry testing of the mass transfer of a scale model rock bag to a cable was undertaken at UWA's Coastal Offshore Engineering Laboratory (COEL). The testing considered effects due to rock bag filling, fill material, multi-bag configurations, and placement tolerances. The aim was to build knowledge of the application of rock bags as secondary stabilisation for cables and CPS subsea. This involved some 1700 individual tests. These tests have provided valuable quantitative data on rock bag performance that can be integrated with the failure envelopes developed during Phase 1 of the JIP.

Phase 2 of the JIP has now commenced with wet testing. AOE is welcoming the involvement of new partners for this phase. Phase 2 is looking at the stability, performance and scour performance of rock bags on erodible seabed. The test scopes include:

·         Preparatory and ancillary testing of rock bag models on sand

·         Seabed mobility influence on rock bag stability

·         Stability of rock bags in proximity to pre-existing scour hole and mapping of scour on multi-bag configurations. Testing is being carried out at the UWA large O-Tube Test Facility in Perth, Western Australia.