Celebrating Reinforced Soil Structures

Abstract

The first use of High Density Polyethylene (HDPE) polymeric geogrid reinforcement in civil engineering was to reinforce and construct a 2.5 m high temporary reinforced soil wall at Newmarket/Silkstone colliery in West Yorkshire, UK in 1980, just 2 years after the first polymeric geogrid was invented by Dr Mercer in 1978 in Blackburn, UK. HDPE geogrid Reinforced Soil Retaining Wall (RSRW) Systems have since been widely used around the world forming various geometries, reaching unprecedented retaining heights in excess of 60 m and serving various functions from supporting open air golf courses to airport runways.

This keynote will give a historic insight on how HDPE geogrid RSRW Systems have evolved in the past 40 years through presenting 10 different case studies, showcasing different types of non-standard reinforced fills including both site-won and purpose-made reinforced fill, the challenges they presented and the lessons learned. By describing the use of variable, non-standard reinforced fills ranging from site-won cohesive fill, to site-won chalk, to site-won mine stone waste, to locally sourced waste pulverized fuel ash, to landfill waste site-won fill, and others, it will showcase the selection criteria and applicability of these various fills depending on the performance requirements of the end structure. It will also highlight critical issues that need to be taken into consideration when using non-standard reinforced soil fills, both at design stage and during construction, such as bespoke site testing as well as contingency and remediation plans to cater for inclined weather or for when site testing does not meet the required performance.

The ultimate purpose of this Keynote is to, as the title suggests, celebrate polymeric geogrid reinforced structures and manifest how they have become established as reliable alternatives to conventional reinforced concrete structures. In many situations, the discovery of polymeric geogrids has opened up possibilities for the construction of extraordinary retaining structures that would not otherwise be feasible or would be extortionately expensive, like the 60 m high polymeric reinforced soil walls featured as alternatives to conventional concrete viaducts in Fujairah, UAE, thus allowing rapid construction and providing earth retaining solutions resulting in attractive, stable, cost effective and maintenance free structures for their 120 years design life.