Cyclic Resistance and Large Deformation Characteristics of Sands Under Sloping Ground Conditions: Insights from Large-Strain Torsional Simple Shear Tests

Summary Particle Image Velocimetry (PIV), a method based on image cross-correlation, is widely used for obtaining velocity fields from time series of images of deforming objects. Rather than instantaneous velocities, we are interested in reconstructing cumulative deformation, and use PIV-derived incremental displacements for this purpose. Our focus is on analogue models of tectonic processes, which can accumulate large deformation. Importantly, PIV provides incremental displacements during analogue model evolution in a spatial reference (Eulerian) frame, without the need for explicit markers in a model. We integrate the displacements in a material reference (Lagrangian) frame, such that displacements can be integrated to track the spatial accumulative deformation field as a function of time. To describe cumulative, finite deformation, various strain tensors have been developed, and we discuss what strain measure best describes large shape changes, as standard infinitesimal strain tensors no longer apply for large deformation. PIV or comparable techniques have become a common method to determine strain in analogue models. However, the qualitative interpretation of observed strain has remained problematic for complex settings. Hence, PIV-derived displacements have not been fully exploited before, as methods to qualitatively characterize cumulative, large strain have been lacking. Notably, in tectonic settings, different types of deformation - extension, shortening, strike-slip - can be superimposed. We demonstrate that when shape changes are described in terms of Hencky strains, a logarithmic strain measure, finite deformation can be qualitatively described based on the relative magnitude of the two principal Hencky strains. Thereby, our method introduces a physically meaningful classification of large 2D strains. We show that our strain type classification method allows for accurate mapping of tectonic structures in analogue models of lithospheric deformation, and complements visual inspection of fault geometries. Our method can easily discern complex strike-slip shear zones, thrust faults and extensional structures and its evolution in time. Our newly developed software to compute deformation is freely available and can be used to post-process incremental displacements from PIV or similar autocorrelation methods.

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Effect of Loading Frequency on Volumetric Strain Accumulation and Stiffness Improvement in Sand under Drained Cyclic Direct Simple Shear Tests

Journal of Geotechnical and Geoenvironmental Engineering ◽

10.1061/(asce)gt.1943-5606.0002706 ◽

2021 ◽

Vol 147 (12) ◽

Author(s):

Zhen-Zhen Nong ◽

Sung-Sik Park

Keyword(s):

Simple Shear ◽

Volumetric Strain ◽

Loading Frequency ◽

Strain Accumulation ◽

Shear Tests ◽

Direct Simple Shear

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DEFORMATION CHARACTERISTICS OF UNDISTURBED SAND AND GRAVEL SAMPLES AT LARGE STRAIN LEVEL

Journal of Structural and Construction Engineering (Transactions of AIJ) ◽

10.3130/aijs.67.103_2 ◽

2002 ◽

Vol 67 (561) ◽

pp. 103-109

Author(s):

Akihiko UCHIDA ◽

Kohji TOKIMATSU

Keyword(s):

Large Strain ◽

Strain Level ◽

Deformation Characteristics ◽

Sand And Gravel

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The Influence of Apparatus Stiffness on the Results of Cyclic Direct Simple Shear Tests on Dense Sand

Geotechnical Testing Journal ◽

10.1520/gtj20190471 ◽

2020 ◽

Vol 44 (5) ◽

pp. 20190471

Author(s):

M. Konstadinou ◽

A. Bezuijen ◽

G. Greeuw ◽

C. Zwanenburg ◽

H. M. Van Essen ◽

...

Keyword(s):

Simple Shear ◽

Shear Tests ◽

Dense Sand ◽

Direct Simple Shear

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Effect of Material Frame Rotation on the Hardening of an Anisotropic Material in Simple Shear Tests

Journal of Applied Mechanics ◽

10.1115/1.4041320 ◽

2018 ◽

Vol 85 (12) ◽

Cited By ~ 1

Author(s):

Kelin Chen ◽

Stelios Kyriakides ◽

Martin Scales

Keyword(s):

Simple Shear ◽

Plastic Anisotropy ◽

Yield Function ◽

Strain Response ◽

Shear Tests ◽

Stress Strain ◽

Anisotropic Yield Function ◽

Torsion Experiment ◽

Thin Walled Tube ◽

Material Frame

The shear stress–strain response of an aluminum alloy is measured to a shear strain of the order of one using a pure torsion experiment on a thin-walled tube. The material exhibits plastic anisotropy that is established through a separate set of biaxial experiments on the same tube stock. The results are used to calibrate Hill's quadratic anisotropic yield function. It is shown that because in simple shear the material axes rotate during deformation, this anisotropy progressively reduces the material tangent modulus. A parametric study demonstrates that the stress–strain response extracted from a simple shear test can be influenced significantly by the anisotropy parameters. It is thus concluded that the material axes rotation inherent to simple shear tests must be included in the analysis of such experiments when the material exhibits anisotropy.

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