Why Gravix?
- Designed for DOT and Heavy Rail applications, but has found a useful option for challenging commercial projects
- Walls as high as 48 feet have been designed and constructed successfully throughout the US and Canada.
- Gravix following AASHTO design methodology for DOT projects typically has stems lengths equal to 0.6H, commercial projects following NCMA design methodology has stem lengths of 0.5H
- Cost reduction and time savings due to smaller (typically 3 to 4 man) crews/100% precast
- Onsite soils can often be utilized with the Gravix system (AASHTO Prefabricated Modular Design Methodology Section 11.11)
- Gravix Slot Construction possible – tighter sites, existing utilities & obstructions
THE DESIGN
The Gravix wall units vary in stem depth dependent upon the wall height, as well as surcharge. A standard unit is 32 SF of face area (8’ x 4’). A typical wall section has the longest units at the bottom and get shorter as they are stacked vertically. Also, at the top of a wall, to follow grade, the casting mold is placed on a tilt table to allow the top of the unit to be cast on a slope. The sloping top edge of the units allows all of the unique geometry top units to be precast and customized for each project. The angled precasting also produces a leveling unit to be used directly below traffic barrier units to allow the uniform traffic barrier unit to parallel roadway grade. The precaster can then provide a complete retaining wall package to the highway contractor. Gravix, providing large precast units and a complete retaining wall system, allows the highway contractor to use less labor, common equipment and achieve higher installation rates, saving time and money.
All of the units incorporate a triangular section in the stem perpendicular to the face that allows the weight of the backfill to bear on the units below, thus transferring downward pressure, which results in a stabilizing effect. In combination, the units create a coherent gravity mass designed to resist overturning, sliding and bearing failure. The design methodology follows the well-accepted AASHTO guidelines of a Prefabricated Modular Retaining Wall for DOT projects and NCMA guidelines for commercial projects.
TOP AND LEVELING UNIT
- Custom top units
- Leveling units to meet roadway grade
- No cap or coping required
To allow the top of the retaining wall to follow grade, angled top units are cast using molds on a tilt table. For Gravix retaining walls that require a traffic barrier, a leveling unit is installed directly below the Gravix traffic barrier unit, also cast on a tilt table, to allow the Gravix traffic barrier to follow roadway grade.
SLOT CONSTRUCTION
- Eliminate temporary shoring
- Provide a safer sloped back-cut
- Reduce infill stone volume
Resources
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