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SRT™

Description: For the Caltrans Route 20/Highway 5 Separation Project, the fill for the overpass ramp embankments consists of clayey, highly expansive soils obtained from nearby sources. After about ten years, the stability of the embankment slopes began to deteriorate as evidenced by slope creep and shallow slides. The slope movement deteriorated the pavement causing numerous cracks parallel to the pavement edge combined with lateral spreading. Additionally, guard rail posts were undermined by shallow slides.

Geopier Solution: Caltrans considered several methods for stabilizing the slopes: lime treatment of the slope, slope inclination reduction using imported fill, non-expansive fill slope overlay, and Geopier SRT™ stabilization. The final project design included a combination of slope reduction, imported fill, and Geopier SRT stabilization. Plate Piles™ were selected to stabilize about 1.5 miles of ramp slopes as a cost saving measure, with minimal earthwork operations and shorter construction time.

The General Contractor scheduled 100 working days to complete the installation of the approximately 8,800 Plate Piles. Installation was completed in approximately 70 days at an average rate of 125 Plate Piles per day. Approximately 2,700 six-foot-long Plate Piles, and 6,100 ten-foot-long Plate Piles were installed using both hydraulic hammers and vibrator plates adapted for installation. The Geopier SRT system for the 20/Highway 5 Separation Project saved Caltrans over $3 million dollars and months of

additional construction time. Caltrans has been monitoring the stabilized slopes for three years. After two years, the slopes and new pavement have performed well with no slope failures or signs of creep.

Plate Piles™ Stabilize Deteriorating Interchange Ramp SlopesWilliams, California

Project: Caltrans Route 20/Highway 5

System: Geopier SRT

Installation: 8,800 Plate Piles

PROJECT hIGhlIGhTS

PROJECT SUMMARY | S04Slope Reinforcement Technology

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