Stainless Steel Hollow Bar and Mesh Stabilizes Failing Slopes at Severn Estuary
Slope failures at the Severn Estuary frequently closed a vital rail line connecting South Wales and North England, disrupting passenger and freight traffic. DYWIDAG was hired to supply the geotechnical material to stabilize the slope in order to prevent future accidents.
The Newport to Gloucester rail line – connecting South Wales with the West Country, Midlands, and north of England – is vital to passengers and freight traffic, but it had a history of slope collapses in the Severn Estuary area. Four downfalls closed the line following a heavy rain in the winter of 2021, further showcasing the need for a long-term failure-prevention solution.
Given the estuary’s location close to the sea and its exposure to rain and wind, a solution to stabilize the slopes was both critical and challenging. A plan was developed to install soil nails and mesh to add surface cover and stabilize the slopes, which reached 37m high at points. The choice to use stainless steel bars and stainless steel mesh doubled the lifespan of the solution from 60 to 120 years, as well as reduce future maintenance and inspections. A hollow bar option was also selected to cut drilling cost and time spent onsite, therefore lessening the disruption to traffic.
DYWIDAG supplied the contractor QTS with all necessary materials: grade316 R32-360 stainless steel hollow bar with 90mm DYWIDAG EYY drill bits and stainless steel mesh. The soil nails and mesh were installed using abseil teams and rigs. All drilling was completed with abseil rigs using air flush and secondary grouting.
The work to secure the slopes on the Severn Estuary was completed on time and within budget.