Yield criteria for glaciotectonically deformed deposits

Abstract

Most glaciotectonically deformed deposits, including varved clays and glacial tills, are characterised by cracks and fissures. This paper presents a method for describing the yield criteria for glacitectonically deformed cohesive deposits using a model of cracked geomaterial with isotropic or anisotropic matrix. The general representation of the limit conditions for anisotropic materials in plane-strain is used to determine the yield criterion. The yield criterion represents a convex, piece-wise surface in the three-dimensional stress space revealing explicitly global, plastic properties of the materials considered. An example of using proposed yield criteria to solve a bearing capacity problem of a strip foundation constructed on a glaciotectonically cracked layer is presented. The lower and upper-bound estimates of limit loads on the strip footing are given. The limit state analysis presented in this paper can be used to solve many other geotechnical engineering problems, for example, the stability of slopes and reinforced walls or the bearing capacity of pile foundations.

First-time landslides in Vashon advance glaciolacustrine deposits, Puget Lowland, U.S.A.

“…In consolidated-drained direct shear tests of overconsolidated glaciolacustrine deposits in northwestern Alberta, Cruden et al (1997) noted considerably higher strength across bedding when compared to tests conducted parallel to bedding. Comparable results have been noted in similar deposits in Europe (i.e, Giraud et al 1991;Florkiewicz et al, 2015). This strength anisotropy should influence the configuration and location of the slide surface and landslide type.…”

“…Arcuate basal failure surfaces in these anisotropic deposits would realize more influence from higher bedding-perpendicular strength and are less critical (more stable) than planar surfaces primarily affected by lower bedding-parallel strength. The anisotropic strengths derived from the direct shear tests and used in our analyses could greatly benefit from additional testing and verification from different locations, though several studies (Giraud et al 1991;Cruden et al, 1997;Florkiewicz et al, 2015) in other regions have also noted considerably higher strength across bedding when compared to tests conducted parallel to bedding for similar deposits.…”