Embankment reinforcement along a river and bridge abutment strengthening was required for a new carriageway in Bridgwater, Somerset, United Kingdom. The project team used a load transfer platform design supported by a combination of geosynthetics: Maccaferri MacTex W1 and ParaLink.
The £18.4 million project has been engineered to alleviate traffic congestion in the town and open up access to surrounding development land.
EMBANKMENT REINFORCEMENT IN SOMERSET
The Colley Lane Southern Access Road (CLSAR) is an important new construction for the town of Bridgwater, Somerset. The 840-metre carriageway, which will include two new bridges and cycle and pedestrian paths, will provide access to the Colley Lane Industrial Estate from the south, thereby easing congestion in the town, especially during rush hour. It will also open up development sites between the River Parrett and the Taunton and Bridgwater Canal, with the new bridges providing easy access.
The geology of the site is characterized by highly compressible and thick alluvial deposits, associated with the River Parrett floodplain and an infilled clay pit. These issues created a risk of excessively large and differential settlements, both along the embankments themselves, and in relation to the relatively fixed approach embankments. To tackle this, a proposal was made to utilize bridge abutments constructed from mechanically engineered earth walls. Maccaferri contributed to the design, which was built around ParaLink as an embankment reinforcement solution for the load transfer platforms (LTPs) over piled foundations.
With this approach, localized differential deformation would be prevented at the surface of the embankments by transferring loads onto the pile caps. To support the abutments on either side of the bridge, the LTPs would transfer the loads of the reinforced earth walls into the piled foundations beneath.
The design’s maximum height of the reinforced soil wall is approximately three meters above the LTP.
ParaLink 400, 500 (for the transverse reinforcement direction) and 800 (for the longitudinal direction) were used across the site. Four different LTPs were designed and installed, including edge piles of 600 millimeters in diameter, and internal piles of 450 millimeters in diameter, with circular pile caps of 900 millimeters in diameter.
Since embankment reinforcement design increased the capability of the embankment fill to arch, the spacing of the piles was also increased to 2.5 meters. This saved the project time and resources. The LTPs were constructed using Class 6I granular fill material.
Learn more about Maccaferri’s engineering services, global operations, and geosynthetics for embankment reinforcement and other applications at www.maccafeeri.com.