The use of high tenacity polyester (PET) geotextiles to reinforce embankment structures over soft unstable subgrades is a common construction technique. This project describes the typical use of such materials.
Over the years the Pacific Highway between Sydney and Brisbane in Australia has undergone major upgrading works to turn it into a dual carriageway freeway. The construction of the section between Yelgun and Chinderah in New South Wales consisted of a dual carriageway freeway 30km in length.
Approximately 10km of this freeway was to be contrusted in geologically old river valleys and floor plains wherethe foundation soils comprised silty clays ranging from 5 to 15m in depth. The undrained shear strength of the clay ranged from 8 to 12kPa, with a 1m thick overconsolidated crust of approximately 25kPa. Along these parts the highway embankment heights ranged from 2 to 5m with a geometry consisting of a 30m wide crest with 2:1 side slopes.