Continuum cavity expansion and discrete micromechanical models for inferring macroscopic snow mechanical properties from cone penetration data

Ruiz, Siul; Capelli, Achille; Herwijnen, A. van; Schneebeli, Martin; Or, Dani

doi:10.1002/2017gl074063

Cited by 9 publications

(9 citation statements)

References 33 publications

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“…The observed discrepancies between the moduli, by up to 2 orders of magnitude, are comparable to recently published results by Capelli et al () and Reuter et al (). To obtain realistic moduli from SMP measurements, a more physically based model has to be developed which accounts for material compaction and finite size effects at the SMP tip (Johnson, ; Ruiz et al, ; van Herwijnen, ).…”

Section: Discussionmentioning

confidence: 99%

Measuring the Elastic Modulus of Snow

Gerling¹,

Löwe²,

Herwijnen³

2017

Geophysical Research Letters

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The elastic modulus is the most fundamental mechanical property of snow. However, literature values scatter by orders of magnitude and hitherto no cross-validated measurements exists. To this end, we employ P wave propagation experiments under controlled laboratory conditions on decimeter-sized snow specimen, prepared from artificial snow and subjected to isothermal sintering, to cover a considerable range of densities (170-370 kg m −3). The P wave modulus was estimated from wave propagation speeds in transverse isotropic media and compared to microstructure-based finite element (FE) calculations from X-ray tomography images. Heterogeneities and size differences between acoustic and FE sample volumes were characterized by SnowMicroPen measurements, yielding an elastic modulus as a by-product. The moduli (10-340 MPa) from the acoustic and FE method are in very good agreement (R 2 = 0.99) over the entire range of densities. A remaining bias (24 %) between both methods can be explained by layer heterogeneities which systematically reduce the estimates from the acoustic method.

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Section: Discussionmentioning

confidence: 99%

Measuring the Elastic Modulus of Snow

Gerling¹,

Löwe²,

Herwijnen³

2017

Geophysical Research Letters

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“…Apart from the structural element size, other parameters may be useful. During snow sintering experiments, van Herwijnen and Miller (2013) found an increase of measured penetration resistance with time related to an increase in bond-to-grain ratio, while snow density remained essentially constant. To correctly reflect this, a microstructural property compensating the increase of the average penetration resistance F would be requiredapart from L, which rather refers to the average distance between breaking microstructural elements.…”

Section: Densitymentioning

confidence: 99%

Comparing measurements of snow mechanical properties relevant for slab avalanche release

et al. 2018

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Snow properties relevant to the fracture processes involved in dry-snow slab avalanche release include weak layer specific fracture energy, slab elastic modulus and density. Various techniques exist to determine these snow mechanical properties, but it is presently unclear how values determined with different methods compare. In the laboratory, the 3-D microstructure of cm-sized snow samples is reconstructed by micro-computed tomography (μCT) so that density and elastic modulus can be computed. In the field, fracture energy and modulus are estimated based on particle tracking velocimetry (PTV) of the displacement field observed during propagation saw tests. Snow stratigraphy is measured with the snow micro-penetrometer (SMP) in either, field or laboratory. We compared SMP-derived properties to correspondingμCT- and PTV-derived values. Values of snow density related well toμCT results and so were SMP-derived elastic moduli related to PTV-derived values. By taking into account snow anisotropy a good relation between SMP- andμCT-derived moduli resulted suggesting the SMP-derived modulus characterizes the components of the modulus perpendicular to the axis of penetration. SMP- and PTV-derived values of fracture energy were correlated. The SMP can provide a bridge between scales and techniques, yet further improvements in signal interpretation are still needed.

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“…The boundary conditions far from the cavity are characterized by a hydro-static pressure p 0 , that was here set to 0. Similarly to Ruiz et al (2017), an interfacial friction coefficient µ = 0.5 between the tip and the snow was considered.…”

Section: Cavity Expansion Modelmentioning

confidence: 99%

“…where Y = 2C cos φ 1−sin φ is the yield stress, a = 1+sin φ 1−sin φ , and A is a constant of integration (see Equation 53 in Yu and Carter, 2002). The resulting penetration force F p acting on the cone is computed similarly to Ruiz et al (2017). The radial force acting on the conical tip is given by:…”

Section: Cavity Expansion Modelmentioning

confidence: 99%

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Experimental Study of Cone Penetration in Snow Using X-Ray Tomography

et al. 2020

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The cone penetration test is widely used to determine the mechanical properties of snow and to delineate snow stratigraphy. Precise knowledge of the snow stratigraphy is essential for many applications such as avalanche forecasting or estimating the snowpack energy budget. With the development of sophisticated, high-resolution digital penetrometers such as the SnowMicroPenetrometer, the cone penetration test remains one of the only objective methods to measure snow stratigraphy. An accurate interpretation of the measured hardness profiles requires to understand the interaction between the cone tip and the snow material. In this study, we measured the displacement induced by the penetration of a conic tip with a radius of 2.5 mm in eight different snow samples using X-ray tomography. The experiments were conducted at a temperature of −10 • C. To recover the full three-dimensional displacements between the tomographic images measured before and after the test, we specifically designed a tracking algorithm which exploits the unique shape of each snow grain. The tracking algorithm enables to recover most of the granular displacements and accurately captures the volumetric strain directly derived from density changes. The measured displacements are shown to be oriented downwards below the tip apex, upwards close to the snow surface, and nearly only radially in between. We observed and quantified the development of a compaction around and below the tip. Surprisingly, we also observed dilation of the snow material close to the snow and tip surfaces in very high-density samples. The radial extent of the compaction zone ranged between 1.6 and 2.3 times the tip radius. These results were compared to existing interpretative models. Although limited to relatively small samples and short penetration depths, these results provide new insights on snow deformation during a cone penetration test, and the validity of these models.

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Continuum cavity expansion and discrete micromechanical models for inferring macroscopic snow mechanical properties from cone penetration data

Cited by 9 publications

References 33 publications

Measuring the Elastic Modulus of Snow

Measuring the Elastic Modulus of Snow

Comparing measurements of snow mechanical properties relevant for slab avalanche release

Experimental Study of Cone Penetration in Snow Using X-Ray Tomography

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