Build Better Tracks: Ballast & Sub-ballast Stabilization with Geogrid
by Mike Misitigh, on October 17, 2019
The American Railway Engineering and Maintenance of Way Association (AREMA), the nation’s foremost authority on industry practices, has recognized the value of geogrid technology for trackbed stabilization by including a chapter on geogrid in its 2010 Manual for Railway Engineering. Indeed, the benefits of using geogrid over soft and firm subgrades have been demonstrated in a number of laboratory and field tests as well as on hundreds of actual installations around the world. And with the introduction of Tensar® TriAx® Geogrid, the benefits are even greater.
How TriAx Geogrids Work: Mechanical Interlock
TriAx® Geogrids stabilize ballast and sub-ballast layers through the principle of “mechanical interlock.” When unbound aggregate is compacted over a geogrid, the coarser particles partially penetrate through the geogrid apertures and lock into position. The load distribution over the underlying subgrade is enhanced, increasing its effective bearing capacity. TriAx Geogrid offers strength at low strain in all directions, preventing large deformations within the aggregate. The geogrid’s ability to confine aggregate particles significantly reduces lateral spreading of granular particles, a major cause of ballast and sub-ballast settlement. This video shows a side-by-side comparison demonstrating how TriAx Geogrid works to combat settlement compared to an unstabilized track.
Tensar TriAx Geogrids are used to stabilize the trackbed structure in two ways:
- Sub-ballast Stabilization: Installed at the bottom of the sub-ballast, TriAx Geogrids help distribute imposed loads more efficiently over the underlying subgrade, leading to a reduction in the required sub-ballast layer thickness.
- Ballast Stabilization: Installed between the ballast and sub-ballast layers, TriAx Geogrids limit lateral particle migration and thereby minimize track settlement. This helps increase the period between maintenance cycles by three to five times.
Expertise You Can Rely On
As the worldwide leader in geogrid technology and design support, Tensar is committed to the success of your rail stabilization project. For more information on cost benefits or design support using a TriAx Geogrid solution, click the button below or contact us.