Residual Interface Shear Strength under Low Normal Stress Conditions: Fid-Bau Portal

Residual Interface Shear Strength under Low Normal Stress Conditions

Westgate, Zachary J.

Accurate quantification of the soil-structure interface shear resistance of shallow foundations, pipelines, tunnels, and other intermediate structures under relatively low normal stress can be difficult. Standard geotechnical testing devices are generally designed to handle large stresses associated with deep foundations and large, heavy structures. At low normal stress, measured interface shear resistance can be complicated by artificial friction from the equipment itself. Over the past decade, various commercial geotechnical laboratories and research institutions have independently developed bespoke solutions to avoid these complications, including tilt tables, modified direct shear boxes, modified ring shear devices, and 1g model test devices. This paper presents a large database (>400 tests) of interface shear test results on a wide range of natural sands and clays performed under low normal stresses. The data populate a conceptual framework that illustrates the factors governing interface shear resistance, comprising soil minerology, soil drainage, normal stress, overloading history, and interface roughness.