myGeobrugg
2024
WSP acted as a design engineer on behalf of Dorset County Council to assess and propose a mitigation strategy for part of the A357 adjacent to the River Stour in Sturminster Newton, suffering from slope instability issues.
Due to the road above being cut into the existing bedrock, this removal of material and additional loading had, over time, caused instability of the slope below the road, and tension cracks had been forming in the recent past.
Because of the road’s proximity to the River Stour, which regularly rises significant distances up the slope, and the road above, often treated with de-icing salts during winter, the corrosion risk on site was of concern.
Alluvium from the river is present directly adjacent to the water body.
Bedrock is mapped as being of the Todber Freestone Member, a limestone.
VSL International was the chosen contractor who installed the nailed solution to stabilise the slope utilising TECCO G45/2, underlain with TECMAT to help prevent erosion control and promote revegetation of the site.
The designer chose an R32 hollow bar type, with nails of significant length to stabilise beneath the road and beyond. Nail spacing varied between 1.5 to 2 metres on site.
Due to the River Stour’s ever-changing height, works on site were difficult, especially when drilling the bottom row of nails. During the works, several structures were encountered near the river’s level, which were unrecorded but thought to be gabion-style structures, which caused disruption to drilling.
TECCO G45/2 stainless was the chosen mesh type due to the slope inclination and to remove the risk of corrosion from either road de-icing salts or possibly from the river. Geobrugg worked with VSL to assist with design and installation queries for the site and undertook regular site visits during the works.
Riverbank
INOX / НЕРЖАВЕЮЩАЯ