Localized shear strength mobilization at geosynthetic interfaces caused by spreading soil downslope

¹ Thiel Engineering, Oregon House, CA, USA
² Consulting Engineer, Paris, France

^* Corresponding author: richard@rthiel.com

Abstract

Localized interface shear strength failures have occurred below the tracks of a bulldozer during placement and spreading of cover soils on slopes lined with geosynthetics. The mechanisms of these types of failures are rarely considered and evaluated in design reports and calculations. A paper on this subject was recently published by Thiel and Giroud [1], but the analyses presented in that paper were limited to upslope bulldozer pushing. The present paper extends those analyses to consider downslope bulldozer pushing and deceleration forces. The paper presents straightforward equations of equilibrium that the user can easily input into a spreadsheet to model various geometries, bulldozer sizes, and shear strengths, and to determine the acceptable size of the soil pile being pushed for those conditions. The equations provided should be useful for design engineers to avoid localized slippage on slopes where bulldozers are spreading soil materials over geosynthetics, or for forensic experts who evaluate why slippage may have occurred.