What is GRS? Geosynthetically Reinforced Soil
"The soil mass of GRS systems
is reinforced in layers with a polymeric geosynthetic (e.g., geogrids or
geotextiles), and the layered reinforcement is attached to facing elements that
constitute the outer wall. Because the facing elements are commonly composed of
articulated units that are not rigidly attached to each other, the wall is
deemed flexible. Various materials, including natural rock, concrete block,
gabion, or timber, may be used for the flexible facing. GRS structures are more
forgiving to differential foundation settlement thus minimizing the bump that
commonly develops between the roadway and bridge. GRS structures are more
adaptable to low quality backfill, easier to construct, and more economical
than their conventional counterparts. GRS structures can be put into
service quickly, can be built by maintenance personnel, and are especially well
suited to projects constructed in areas that are difficult to access with heavy
equipment. GRS structures are an economical alternative for temporary
structures, because of their easy demolition and the recyclable nature of their
components, and for emergency work, because of reduced lead time and lower
equipment requirements."
An excerpt from the forward of NCHRP
Report 556 Design
and Construction Guidelines for Geosynthetic-Reinforced Soil Bridge Abutments
with a Flexible Facing
How is Defiance County using it?
For culvert headwalls and wingwalls.
For bridge abutments
Bowman Road -2005
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As can be seen from the above photos, the beams actually sit on the fabric reinforced stone and there is no cast-in-place concrete in the structure
Link to FHWA Interim Implementation Guide- New 2011
For more information contact Warren Schlatter, Defiance County Engineer
Links
FHWA's Turner Fairbank Highway Research Center
FHWA's Every Day Counts - GRS-IBS
April
2011 FOCUS article Building Bridges the Geosynthetic Way
April 2006 FOCUS article Building the Bridge of the Future with GRS Technology
Design and Construction Guidelines for Geosynthetic-Reinforced Soil Bridge Abutments with a Flexible Facing an NCHRP document detailing design guidelines.
GRS Bridge Piers and Abutments FHWA Research Report
Public Roads Article - July/August 2000 Geosynthetic Reinforced Soil Structures Can Carry the Load
Better Roads Article -February 2002
Erosion Control Article November 2003