The October 4 2018 COPRI Houston Conference lecture Breakwater Caisson Design was presented a few days before the first Nador Caisson was loaded out in Morocco.

This video illustrates a success story.  The loading out the 3,000 tonne caisson (that had been slipformed on land) is shown onto a semi-submersible barge.  The barge is towed to relatively deep water and ballasted down, until the caisson can be floated off.  The caisson is then towed to a moderate water depth where it is ballasted down and stored until all caissons are ready for final installation.

All phases of the operation required naval architecture calculations for the hydrostatic stability of the caisson and barge. About 100 Caissons make up the breakwater for the new harbor at Port Nador.

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The full lecture can be viewed at CAISSON DESIGN VERIFICATION.  This lecture was presented at the ASCE COPRI 2018 Houston Chapter Conference.

A cross section through the main breakwater is shown below:

Wave forces and safety factors against sliding and overturning are computed with Excel and shown in the Excel chart below:

The installation requires afloat stability checks as the caisson is removed from the semi-submersible barge.

The Excel package goes on to calculate motions of the floating structure in waves, based on closed form analytical solutions.

For each degree of freedom, the diffraction and Froude-Krilov forces are discretely calculated for wave attack in the primary plane of motion, at a range of wave periods.  Mechanical admittance is calculated and dynamic response is computed.  Response at intermediate attack angles is interpolated.

This paper describes coastal civil engineering and naval architecture good practices applied to design optimization of concrete caissons, typically constructed by slipforming.

Always check results with experienced engineers and naval architects.  It is easy to make mistakes in input data.

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