As marine engineers, we are very aware of the power of Mother Nature. Her seas lap and lacerate our shores; her weather systems keep us alive and cause equal amounts of havoc for our modern lives. One way we can keep the harmony between civilisation, protecting our coastline, and keeping the economy moving on transport systems and infrastructure is by using preventative measures such as scour protection.
What is scour protection?
Scour is an engineering term for the erosion of soil underwater, usually concerning sub-water structures. This is usually caused when fast-moving water removes sediment from around the foundations of a structure, causing damage that compromises the structural integrity of the construction’s materials. We’ve discussed in previous blogs the importance of planning a project to ensure safety and longevity. One of the essential factors to mitigate scour in marine engineering is to install scour protection systems. Bridges traverse a vast majority of our waterways, so tides and currents that cause the seabed to decay can cause significant problems.
Why is scour protection so important?
According to Network Rail, scour has been the leading cause of bridge failure in the UK over the last 100 years. Bridges can suffer from scouring when flow conditions change or when rivers go into flood. This scour can threaten the structural integrity of bridges if allowed to develop, leading to settlements and failure. With our climate changing rapidly, the social anxiety about the effects of increased water flow, whether due to flooding or sea-level changes, creates a renewed urgency in detecting scour and using scour protection measures to maintain the safety of our water spanning structures. Increased efforts to monitor the earth’s hydrology helps to plan ahead when designing bridges, for example. But adding scour protection solutions to pre-empt water damage is advised and is a measure that Kaymac Marine builds into their development plans when undertaking new sub-water projects.
How does Kaymac Marine implement scour protection works?
The factors causing scour to develop are complex and differ according to the type of structure. But whatever the problem, to enable us to develop a robust solution, we need to get our experienced team under the waterline to carry out an initial detailed inspection to gather accurate data for each unique situation. Our commercial diving operations allow Kaymac experts to gain access to detect and inspect scour defects. This is the first step in identifying how to approach the project ahead, taking ambiguities, risks, and issues into complete account.
Once the detailed inspection report has been produced, our chartered engineers develop an innovative solution to repair the damage and alter scour susceptible structures using scour protection methods to sustain them. Each of our multi-skilled commercial divers are experts in constructing formwork underwater and temporary works for scour repairs and protection schemes – whatever process that may be.
Which scour protection solutions are available?
Our scour protection solutions have historically been to bridge structures, particularly pier and abutments, as well as river embankments and tidal estuaries. We can protect against the aggressive movement of inland waterways, tidal waters, and propeller wash.
Installing Rock Armour as protection against scouring is a proven method, often used to protect the base of seawalls, longitudinal defence similar to Rip Rap applications, or hydraulic structures such as Groynes and Breakwaters. The rock used will typically be a hard igneous rock that is exceedingly resistant to erosion. Rock Armour is a more significant size material. It typically ranges in size from 400mm to 1500mm plus, depending on the job specific requirements, and is used in specialist river defence or sea defence applications. When the currents hit the rock, they are only partially reflected and can flow around the rocks, expending their energy less quickly, reducing scour. As an example, Kaymac placed 6000 Tonne of Rock armour along the bank of the River Mersey on the Carrington Fluvial Erosion Scheme, which provided effective repair and protection to the river bank protecting the high voltage tower.
In recent years, Proserve fabric formwork mattresses have become a popular solution due to the design life of 50 years and that it can be installed in wet and dry conditions. The Fabric formed concrete mattress seals against the piers and abutments, preventing flow from eroding material under the mattress. The slab consists of high-quality plain concrete, able to resist flows of over 6m/s. The slab extends beyond the structure, outside the influence of both local and contraction scour. The edges are then usually protected with riprap to prevent underscour from occurring or embedded as appropriate. This application has been used on projects Spey Viaduct and Redbridge recently.
Using civil engineering techniques to reinforce foundations, install geotextile systems, soil nails to secure embankments, and placement of rock armour, the team at Kaymac can stabilise embankments damaged by landslips, wall collapses, fluvial erosion, or other attrition.
For more details on how Kaymac Marine can help to repair or protect structures from scour, please visit our website or give our friendly team a call today.