First choice solution

摘要

Twenty years ago, the use of geosynthetics in construction may have been considered to be "alternative" technology. But as products have been developed and as engineers have gained confidence in their use, geosynthetics today are often the first choice solution rather than last resort. Since the 1970s hundreds of millions of square metres of synthetic geogrids have been installed that are quite literally holding together the highways, railways, runways, and embankments of the world. Tensar geogrids were developed by the Netlon Group of Blackburn, Lancashire, for reinforcing soil structures. Tensar geogrids are high strength polymer grids manufactured from extruded high density polyethylene/polypropylene sheet which is then punched with a precise pattern of holes and stretched to form a uniaxial or biaxial grid. This stretching process ensures uniform orientation of the polymer's long chain molecules which dramatically increases tensile strength and stiffness. The Tensar geogrid structure is an extremely efficient soil reinforcing element because of the unique interaction it develops with the soil particles. Together the grid and soil form a composite engineering material. Applications for Tensar reinforced soil include retaining walls and embankments as these two highways case studies at Barnsley and Blythe illustrate.