Shallow Landslide Repair Analysis Using Ballistic Soil Nails: Translating Simple Sliding Wedge Analyses into PC-Based Limit Equilibrium Models

Ballistic soil nails have been used in the United States to repair shallow roadway landslides for nearly 20 years. The U.S. Forest Service/Federal Highway Administration "Application Guide for Launched Soil Nails" is the principal design manual for designing with ballistic soil nails and employs a simplified sliding wedge analysis using limit equilibrium concepts to determine the factor of safety of a slope reinforced with soil nails. The design methodology quantifies the tensile and shear resistance provided by the individual nails, but is limited to linear failure surfaces in homogenous materials. The paper explains some of the recent advancements in launched soil nail design methodology and provides a conceptual methodology for translating sliding wedge analysis input parameters into standard PC-based limit equilibrium slope stability programs. An improved method of estimating bond strength is presented. The shear contribution of ballistic soil nails, often ignored in conventional soil nail design, is shown to be an important contribution to the stability of ballistic soil nail landslide repairs.