A new approach to quantify the anisotropy of hydromechanical strains in clay-rock at the gallery scale

Hedan, Stéphen; Valle, Valéry; Cabrera, Justo; Cosenza, Philippe

doi:10.1016/j.ijrmms.2018.07.004

Cited by 5 publications

(9 citation statements)

References 30 publications

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“…The set of pictures and the H-DIC algorithm have demonstrated the anisotropy of hydric strains along the directions parallel and perpendicular to the stratification and the presence of subhorizontal and subvertical cracks with intervals of 34.97 to 69.4 mm between subhorizontal cracks. 10 These observations and Figure 1 confirm the presence of mixed-mode I-mode III fractures in the argillaceous rock submitted to natural variations in hygrometry. Figure 7 presents, on a state close to an extreme state (ΔRH = 73.71%, ΔT = 7.22 C), the jump maps (o, s) and α-map calculated using the H-DIC algorithm.…”

Section: Applications To a Real Casesupporting

confidence: 72%

“…According to the results of Hedan et al 10 regarding the variability of the anisotropy ratio of argillaceous rock submitted to a natural annual cycle, the scheme of principle ( Figure 1a) confirms that the spatial heterogeneity of strains induces opening and shear modes along the boundaries of blocks 1 and 2 ( Figure 1b). The opening value o _imp is constant and equal to 0.645, and in the shear mode, s _imp evolves slightly but linearly in the range of −0.615 to −0.625.…”

supporting

confidence: 60%

“…From Figure 7, the subhorizontal and subvertical desiccation cracks were divided according to the θ H value, and the ranges were chosen to have a good continuity of cracks. In the previous study, 10 the mean orientation of the subhorizontal crack according to the coordinate system of the camera was 1.74 rad. A qualitative analysis shows that the θ H value was in the range of 1 to 2.2 rad for subhorizontal desiccation crack and −π to 1 rad and 2.2 to π rad for subvertical desiccation cracks.…”

Section: Applications To a Real Casementioning

confidence: 90%

“…The area of each block was different to account for the geometric variability of the natural block. 10…”

Section: Rigid Body Movement and Deformation Of Blocksmentioning

confidence: 99%

“…By simulation, Lisjak et al 9 (Mont Terri site) showed the presence of mixed-mode (I/II) fractures in specimens subjected to compressive tests. Recently, Hedan et al 10 showed a variety of subhorizontal and subvertical strains in transversely isotropic argillaceous rock. This variability induces a different in-plane movement for each cracked block, which results in the presence of mixed-mode I-mode III fractures ( Figure 1).…”

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confidence: 99%

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Subpixel precision of crack lip movements by Heaviside‐based digital image correlation for a mixed‐mode fracture

Hedan

Valle

Cosenza

2020

Strain

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This study reports on the Heaviside-based digital image correlation (H-DIC) procedure and its application in fracture analysis. This improved DIC procedure was proposed to solve the uncertainty problems at the vicinity of the crack and to evaluate the opening and shear movements of crack lips and the orientations of cracks in the subset. Some tests were conducted to demonstrate the performance of the H-DIC algorithm. An application on argillaceous rock mass exhibiting multiple mixed-mode fractures is shown to validate the efficiency and robustness of the proposed method. This application consisted in processing images acquired from an experimental investigation performed in a gallery front submitted to climatic seasonal variations. The results illustrated how the H-DIC procedure enables to localise and to quantify the opening, shearing and orientation of subpixel cracks. A sensibility study performed on the opening and shear components demonstrated that the precision of crack aperture by H-DIC procedure is close to 0.14 pixel and the spatial resolution is equal to one pixel. Moreover, the crack area was calculated from local apertures on a monitoring duration of 1 year, and a maximum value of 595.8 mm 2 in winter was obtained. K E Y W O R D S crack area, crack orientation, digital image correlation, fractured structure, full-field measurement, lip displacements, mixed-mode fracture 1 | INTRODUCTION Desiccation cracking, which results from the heterogeneous spatial organisation of tensile stresses, the heterogeneities of mineralogy or the orientation of swelling clay particles inside geomaterials, modifies the hydraulic properties of clayey geomaterials (e.g., Vogel et al, 1 Coppola et al, 2 and Baer et al 3). Consequently, the water movement and solute transport in unsaturated cracked clayey soils become more complicated to describe and model. Indeed, models regarding water movement in cracked soils further require both dynamic crack patterns and varying hydraulic descriptions. 3,4 Thus, knowledge about the crack morphology seems indispensable for modelling the soil cracking mechanism and water transport in unsaturated cracked soils. 4,5 In recent years, the measurement of crack patterns has evolved from field measurements to automatic recognition and quantification using digital image analysis. Researchers frequently use digital imaging methods for crack quantification, 3-5 wherein superficial crack patterns are quantified using geometric and morphological indexes. Two limits of the previous approaches based on digital imaging methods are (i) the precision of desiccation crack detection (always greater than or close to 1 pixel) and (ii) their application being limited to

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Section: Applications To a Real Casesupporting

confidence: 72%

supporting

confidence: 60%

Section: Applications To a Real Casementioning

confidence: 90%

“…The area of each block was different to account for the geometric variability of the natural block. 10…”

Section: Rigid Body Movement and Deformation Of Blocksmentioning

confidence: 99%

mentioning

confidence: 99%

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Subpixel precision of crack lip movements by Heaviside‐based digital image correlation for a mixed‐mode fracture

Hedan

Valle

Cosenza

2020

Strain

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Effect of microstructure on hydric strain in clay rock: A quantitative comparison

Fauchille

Hedan

Valle

et al. 2019

Applied Clay Science

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In-situ synchrotron characterisation of fracture initiation and propagation in shales during indentation

Fauchille

Chandler

et al. 2021

Energy

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A new approach to quantify the anisotropy of hydromechanical strains in clay-rock at the gallery scale

Cited by 5 publications

References 30 publications

Subpixel precision of crack lip movements by Heaviside‐based digital image correlation for a mixed‐mode fracture

Subpixel precision of crack lip movements by Heaviside‐based digital image correlation for a mixed‐mode fracture

Effect of microstructure on hydric strain in clay rock: A quantitative comparison

In-situ synchrotron characterisation of fracture initiation and propagation in shales during indentation

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