Axisymmetric Shearing of Sand-Steel Interfaces under Axial and Torsional Loading

Abstract

Interfaces of soils with man-made materials play a major role in geotechnical systems, from deep and shallow foundations to landfills and retaining walls. Accordingly, it is of paramount importance to understand the behavior of interfaces involving different construction and natural materials. For soil-man made material surface interfaces, a linear increase in strength occurs with increasing surface roughness until the interface shear strength reaches that of the soil. Any subsequent increases in surface roughness result in no additional change of observed system interface strength. In this paper a series of laboratory axisymmetric interface shear tests involving axial and torsional loading are presented. This study involves interface shear tests between Cone Penetration Test (CPT) friction sleeves with different roughnesses and different sands. CPT sleeves with surface roughness ranging from that of the conventional smooth sleeve to those with texture elements of 1 mm in height are tested with sub-rounded and sub-angular medium sized sands. This laboratory study is part of an effort to improve soil characterization and pile design by means of the CPT that utilizes multi-sleeve modules. The next generation system expands the use of friction sleeves with different roughnesses to include response measurement under both axial and torsional loading.