Practice and Research of Geosynthetic Reinforced Soil Walls in Australia - Reinforced Soil Engineering: Advances in Research and Practice - page 247

performance requirements are seen to be high. Since 1991, GRS walls have been
gaining wide market acceptance. The highest GRS wall built to date has a
maximum height of about 19 m. A number of GRS abutment walls supporting
bridge decks have been successfully constructed. A GRS wall in wraparound
construction was also used effectively in the construction of a temporary wall
(that was dismantled subsequently) at the Great Western Highway west of
Sydney. However, the design practice for GRS walls is, at the time of writing, by
no means standardized. There is no Australian Standard specific for the design
and construction of reinforced soil walls. The draft Australian Standard on
Reinforced Soil Walls (DR-91271, 1991) evolved into a draft Australian
Standard on Earth Retaining Structures (DR-96405, 1996), still under revision at
time of writing. The latter is a broad-based document that contains some
references to the principles for the design of GRS walls. Hence, the design
practice differs between states. Within a state, the design practice for projects
under the jurisdiction of the local government may differ from that under the
jurisdiction of the SRAs. This paper is focused on GRS walls under the
jurisdiction of the road authorities of the eastern states (Queensland, New South
Wales, and Victoria). Research in GRS walls is often linked to specific
requirements of Australia or specific projects. In the latter case, some of the
research outcomes may not be published in the public domain.
2 OVERVIEW
GRS walls for the SRAs are often built with a “hard” near-vertical surface. Either
articulated precast concrete panels or modular blocks have been used as the
facing. Both high-density polyethylene (HDPE) and high-tenacity polyester
reinforcements, in either strap or grid form, have been used successfully.
Although fine-grain soils can be used as the fill material in the reinforced zone, it
is not uncommon that a granular fill (with less than 15% fine content) is required
by an SRA. Hence, the term “select fill” is often used to designate fill material in
the reinforced zone.
The construction of reinforced soil wall for the SRAs was often based on
the design and construct contract. This means a specialist GRS contractor is
responsible for both the design and construction of the GRS walls at an agreed
price. As such, GRS walls have to compete with reinforced soil (RS) walls based
on metallic reinforcement system and conventional retaining walls on cost-
effectiveness. This contract system encourages innovation and cost-effective
design. However, the implementation of such a form of contract for the
construction of retaining walls is not easy, because the design requirements,
being part of the contract document, will be subject to both contractual and
technical interpretation. Although the GRS wall design requirements can be