Testing and strengthening retaining structures

How do you ensure that a large number of flood defences and objects meet the safety requirements on time? District Water Control Board of Holland North District (HHNK) faced the challenge of testing and strengthening more than 300 km of regional flood defences, 500 water-retaining civil engineering works and 1 million non-water-retaining objects. The objectives were clear: all defences had to be assessed by 2024, and the most urgent reinforcements already had to be underway. HHNK hired Iv to supervise this process efficiently and design and implement the necessary reinforcements.

The theoretical principles and experience in practice were far from aligned when the programme started. Many kilometres of defences failed in theory, while they had been functioning well in practice for years. This led to kilometres of defences being wrongly condemned, and over-dimensioning occurred when designing reinforcements.

Iv’s approach to tackling this challenge consisted of three crucial elements.

• Performing new field and practical research, such as settlement tests, whereby the actual deformation of the subsoil was measured. This data was fed back into the models and resulted in significant savings on soil quantities and space requirements for reinforcements.
• Developing more innovative and more accurate calculation tools supported by apps and Artificial Intelligence. This allowed thousands of flood defence civil engineering works and no less than 1 million non-water-retaining objects to be tested quickly and efficiently, resulting in high cost efficiency, uniformity in testing and building an extensive digital database for the area managed by HHNK.
• Developing new knowledge and guidelines for flood defence design, including the guideline ‘designing longitudinal structures for regional flood defences’, which is now being further developed nationally in collaboration with STOWA.

This approach resulted in a more realistic and accurate condemnation of the flood defences and leaner reinforcement designs, which brought significant costs, effort, and sustainability advantages.

Due to the positive results and the pleasant collaboration, Iv received a new assignment to continue supporting HHNK in reinforcing regional flood defence structures for the next six years.