Linking Carbonate Sand Fabric and Mechanical Anisotropy from Hollow Cylinder Tests: Motivation and Application: Fid-Bau Portal

Linking Carbonate Sand Fabric and Mechanical Anisotropy from Hollow Cylinder Tests: Motivation and Application

Lim, Ming Fook / Carraro, J. Antonio H. / Gourvenec, Susan

In addition to density and stress, fabric is also a key state variable strongly affecting soil behavior. While fabric influence on mechanical behavior of soils has been investigated experimentally, the available database is limited in terms of boundary conditions and soil types tested. Offshore carbonate sediments are of special interest for offshore geotechnical analyses due to their prevalence in tropical waters and unique mechanical behavior that stems from their mostly biogenic origin. A key gap in the availability of experimental data on soil fabric relates to the anisotropy of offshore carbonate sediments. In practice, anisotropy studies (whether rigorously correlated to fabric or not) are typically carried out experimentally for simple boundary conditions such as idealized plane strain and axisymmetric states. In real geotechnical applications, stress paths subjected to soil elements in the field are far more complex, often involving the combined variations of both the orientation and magnitude of all three principal stresses. This paper presents a new multi-scale approach to assess soil fabric at the micro-scale level and relate it to the macro-mechanical response observed for generalized loading conditions. A new sampling method is illustrated that enables preservation and evaluation of the fabric of offshore sediments specimens following generalized stress disturbances imparted by a hollow cylinder apparatus. The link between fabric evolution and the observed stress-strain behavior of sand is discussed along with preliminary results. The approach is part of a broad framework that will be used to systematically study the evolution of soil fabric and anisotropy and their relationship to multi-directional loading scenarios.