Anisotropic Stiffness and Shear Strength Characteristics of a Stiff Glacial Till

AbstractGlacial tills are widespread across North America, northern and central Asia, and northern Europe, where they are also found under the Baltic, North, and Norwegian Seas. Their geological and geotechnical characterization is important to a wide range of onshore and offshore engineering projec...

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Bibliographic Details
Published in:Journal of geotechnical and geoenvironmental engineering 2020-12, Vol.146 (12)
Main Authors: Liu, Tingfa, Ushev, Emil R, Jardine, Richard J
Format: Article
Language:English
Subjects:
Anisotropy
Cylinders
Elastic anisotropy
Elastic limit
Field tests
Geotechnical engineering
Glacial till
Gravel
Horizontal loads
Horizontal orientation
Offshore engineering
Overconsolidation
Ratios
Sediments
Shear strength
Shearing
Stiffness
Technical Papers
Vertical loads
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Summary:AbstractGlacial tills are widespread across North America, northern and central Asia, and northern Europe, where they are also found under the Baltic, North, and Norwegian Seas. Their geological and geotechnical characterization is important to a wide range of onshore and offshore engineering projects. One aspect of tills on which little has been reported is their mechanical anisotropy. This paper reports coordinated hollow cylinder apparatus (HCA) tests, triaxial shearing, and small-strain stress probing experiments, supported by index testing, on high-quality samples of natural low-to-medium plasticity, high overconsolidation ratios (OCR) stiff clay-till from the Bolders Bank Formation at Cowden, near Hull in the UK. Material variability and sampling bias are inevitably introduced by the till’s erratic gravel particles and fissure systems, and these aspects are addressed carefully. The experiments investigated the till’s stiffness and shear strength anisotropy from its limited linear elastic range up to ultimate failure, showing that stiffnesses are higher in the horizontal direction than in the vertical and that higher undrained shear strengths develop under passive horizontal loading than active vertical loading. Comparisons are made between the till’s patterns of anisotropy and those applying to previously studied sediments, and reference is made to in situ stiffness measurements. The important implications of anisotropic behavior for geotechnical design and the interpretation of field tests are emphasized.
ISSN:1090-0241
1943-5606
DOI:10.1061/(ASCE)GT.1943-5606.0002387