Stabilizing Landslides in the Pennington Shale with Drilled Ground Anchors-Video

Video Transcription

Video Summary

Robert Jowers of the Tennessee Department of Transportation presented an I-40 slope-stabilization project in Roane County, where deep, water-sensitive Pennington shale colluvium has caused recurring landslides. The shale’s variable layers and high permeability can create hydrostatic pressures, while the steep Cumberland Plateau escarpment makes excavation and conventional repairs difficult.<br /><br />Past measures—including drainage, reduced embankment heights, and other stabilization methods—had not stopped movement. After severe statewide rainfall in February 2019, TDOT commissioned extensive investigation of the westbound slope: 35 borings, six inclinometers, 22 vibrating-wire piezometers, resistivity surveys, and detailed geological mapping. The work identified four landslides and informed a ground-anchor design.<br /><br />The final contractor proposal used roughly 750 high-capacity, up-to-240-foot anchors and heavy precast concrete bearing blocks. Jowers described drilling, anchor installation, stressing, quality control, and construction progress. The eastbound slope has been stabilized; westbound work was about 50% complete at the time of the presentation. He emphasized the value of thorough site characterization and a detailed design for bidding, while noting that long-term anchor performance and possible shale relaxation remain questions for future monitoring.

Keywords

I-40

slope stabilization

Roane County

Pennington shale

landslides

ground anchors

Cumberland Plateau

TDOT