Long Term Performance Monitoring of Shallow Slope Stabilization Utilizing Recycled Plastic Pins

Abstract

Shallow slope failures are prevalent within the North Texas region. As highway slopes are underlain with high plastic clayey soils that experience cyclic shrinking and swelling, the soils shear strength generally decreases as the soil softens, making the soil more susceptible to sloughing and landslides. The Texas Department of Transportation (TxDOT) generally executes a rapid repair method as an economical option for repairing the slope. This method includes the failed soil removal, replacement, and recompaction to rectify the slope surface. While economical initially, this rapid repair technique may potentially prove to be costly with repeated repairs as the method does little to increase the soils shear strength. Recycled Plastic Pins (RPP), manufactured with recycled plastic and waste material, can potentially be utilized as a sustainable and cost effective alternative to stabilize surficial slope failures, in addition to alleviating the maintenance costs associated with continual repair. The present study looks at the long-term performance of three slopes stabilized utilizing RPP. The three slopes are located at US-287 near the St. Paul overpass in Midlothian, the I-35 overpass at Mockingbird Lane, and SH-183 near the DFW airport. While previous studies have been conducted on the performance of RPP as a slope stabilization measure, the period of observation is limited. Additionally, both topographic surveys and inclinometer measurements were performed to link both the vertical settlement and horizontal displacement. Based on the performance monitoring results, it was concluded that RPP provided adequate resistance against shallow slope failures. Moreover, near the location of each site during the monitoring period, several shallow slope failures were observed.