The Geoweb Soil stabilization system - Case Study

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Courtesy of Presto Geosystems

The GEOWEB® system is a proven technology for solving challenging soil stabilization problems common in the railroad industry. Railway engineers worldwide have successfully applied the GEOWEB® cellular confinement technology to 1) provide a high-stiffness roadbed foundation at grade under track, crossings and turnouts, particularly in areas of weak soils, 2) eliminate deterioration from sloughing and spreading of embankment slopes and 3) stabilize drainage channels.

THE Cost benefits of the solution
The GEOWEB® system stabilizes the subballast layer, reducing vertical and lateral stresses and significantly reducing subsoil movement. Stabilization within the system provides a longer lasting trackbed profile that extends rail and track-work component service life, while significantly reducing maintenance cycles and cost. The cost-benefit ratio is high because of its overall flexibility and low-cost installation rate. Long-term test results and successful applications worldwide confirm the benefits of the GEOWEB® system.

The Challenge
A section of a Class I Railroad track had a history of track misalignment and weekly maintenance due to settlement caused by weak clay subbase material. The track, a main artery into Dallas, handled up to three trains per day. Previous methods of stabilization, including pole slide pilings, lime-fly ash injections, and concrete caps had all failed to provide long-term track stabilization.

THE Installation
The GEOWEB® material was placed under 300 feet of singletrack on a 25-foot high, elevated bridge approach embankment comprised of clay and shale fill. Extensive tamping was required to establish and maintain the track cross elevation. Rail and ties along with a two-foot deep layer of ballast and sub-ballast were removed over a 300-foot length of track. After grading and leveling, a 20-ounce nonwoven geotextile was installed as a separation layer. Next, a four-inch layer of sand was placed over the geotextile. GEOWEB® sections were then positioned providing a 20-foot wide bed under the ties. After infilling the sections with limestone screenings, the 6,000 sq. ft. area was compacted. A three-inch surcharge was added, leveled and new track and ties panels were placed. Finally, ballast was dumped and tamped, and the track was leveled and returned to service.

The Results
This section of track was repaired with the GEOWEB® system in less than one day, allowing the track to be fully operational the same day . Consistency of the track modulus was maintained after installation, allowing the work order to be lifted and speed returned to its normal 40 mph just 24 hours later. After six weeks, no maintenance was required on this track section that normally required weekly maintenance.

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