Launched Soil Nails: Application Evaluation in Shallow Landslide Mitigation

摘要

With the development of launched (or ballistic) soil nails, a new suite of remediation concepts are now available for repair of shallow landslides and severe erosion problems. The nail launcher uses an air cannon to insert 1.5 in diameter steel or fiberglass tubes into the earth up to 20 ft. These tubes can serve much like traditional soil nails or micropiles but can save significant cost and time in repairing shallow landslides. When the tubes are perforated, they can also serve as horizontal drains. The perforated tubes can be used as conduits for pressure grouting, and can serve as receivers for inclusions that can increase their tensile and shear capacity. Grouting, galvanization, and the use of fiberglass nails can minimize corrosion issues. Shotcrete can be applied in traditional and novel ways to augment a complete structural solution. Alternately, a variety of erosion control mats and blankets can be tied to the protruding nail tips. This combination addresses not only the shallow landslide, but also the surficial erosion often associated with them. Launched soil nail technologies also allow for remediation of landslides and erosion using a fraction of the steel, concrete, and other materials used in more traditional repairs, with a much reduced site impact. Where traditional landslide remediation methods require significant excavation and replacement of soils, launched soil nails cause little or no disruption to the surrounding vegetation and soils, which minimizes related erosion, water quality issues, and overall site impact. This paper outlines the technical characteristics of launched inclusions (nails, micropiles and drains), the types of erosion problems they are suited to repair, and their advantages and disadvantages compared to more traditional shallow landslide remediation measures including excavation/replacement and rock buttresses.