Basal Reinforcement
2016
Dawlish, Devon
Redrow Homes
Harris and Harris Construction Ltd
Wardell Armstrong
Shutterton Park
Global view of the site – Piling configuration
Installation of the longitudinal layer of ParaLinkĀ®
Installation of the transversal layer of ParaLinkĀ®
Layers of ParaLinkĀ® within compacted 6N material
Final compaction operation for the basal reinforcement
Finished surfacing on the road
Problem
Redrow Homes proposed a new residential housing development within land off Shutterton Lane, Dawlish, Devon. The development comprises a mixture of private and affordable housing, private gardens, public open spaces, and all associated infrastructure.
Part of the infrastructure design required a new culverted road over the existing brook, connecting the two sections of the site. The proposed road crossing spans an existing brook with soft soil deposits on both banks. The site investigation works carried out in the area of the proposed crossing identified variable conditions with very soft soils including peat.
Solution
It was then proposed to use a granular material SFHW type 6N for the 300mm depth of the load transfer platform with the lower strength site-won material for the remainder of the embankment (with the exception of carriageway construction). The design of the load transfer platform was carried out to BS 8006-1:2010 using Marstonās formula. A surcharge load of 30kPa was assumed at road level and acting over the entire width of the embankment.
The load transfer platform consisted of two orthogonal layers of high-strength geosynthetic reinforcement placed directly over the pile caps. The design required one layer of ParaLinkĀ® 450 in the longitudinal direction (i.e. perpendicular to the line of the concrete culvert) and a layer of 500kN strength in the transverse direction (i.e. parallel to the line of the concrete culvert). However, two layers of ParaLinkĀ® 250 were selected for the transverse direction to allow the required bond length to be achieved within the available space. The properties of ParaLinkĀ® 250 and ParaLinkĀ® 450 are in accordance with the British Board of AgrĆ©ment, Roads and Bridges AgrĆ©ment Certificate No 03/4065.