Evolution of Local Strains Under Uniaxial Compression in an Anisotropic Gypsum Sample

Caselle, Chiara; Umili, Gessica; Bonetto, Sabrina Maria Rita; Costanzo, Daniele; Ferrero, Anna María

doi:10.1007/978-3-030-21359-6_48

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Another element that may affect the mechanical response of branching selenite gypsum is the material anisotropy and the iso-orientation of the crystals. As illustrated in [31], the iso-orientation of crystals in branching selenite gypsum influences the orientation of the failure propagation under stress: the material will show, indeed, a higher propensity to develop cracks parallel to the preferential orientation of the crystals rather than perpendicular to them. The material description proposed in this paper highlighted how this iso-orientation is identified not only at the sample scale but also at the scale of the quarry site (see Figure 2).…”

Section: Implications For Quarry Exploitationmentioning

confidence: 99%

Preliminary Mineralogical Characterization of Branching Selenite Gypsum: New Insights for the Paleoenvironmental Reconstruction and Mechanical Characterization

Caselle¹,

Pastero²,

Cavagna³

et al. 2022

Minerals

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The present study proposes a characterization of textural and mineralogical features of branching selenite gypsum lithofacies from the Monferrato area (NW Italy). This facies is considered to have appeared during the sequence of the primary lower gypsum of the Messinian Salinity Crisis starting from the sixth stratigraphical cycle, providing a useful tool for stratigraphic correlation throughout the Mediterranean. It is often associated with thick and continuous beds that are exploited by open-pit and underground quarries. We provide the results of a characterization of the non-gypsum minerals that represent approximately 10% in weight of the rock. Mineralogical data were collected with energy-dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction (XRPD) techniques. In addition, a detailed characterization of clay families was performed through dedicated XRPD analyses. Results highlight the presence of detrital minerals (quartz, feldspars and clay minerals), calcite, dolomite and epsomite. Clay analysis registered the existence of five different families (illite, chlorite, smectite and two mixed layers). These mineralogical data suggest that the origin of this lithofacies is connected to both depositional processes and in situ precipitation processes under different conditions of saturation of the brine (respectively undersaturated and supersaturated in sulfates). The mineralogical and textural heterogeneity also represents an important element in controlling the mechanical response of the material and the consequent stability of quarry sites.

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Section: Implications For Quarry Exploitationmentioning

confidence: 99%

Preliminary Mineralogical Characterization of Branching Selenite Gypsum: New Insights for the Paleoenvironmental Reconstruction and Mechanical Characterization

Caselle¹,

Pastero²,

Cavagna³

et al. 2022

Minerals

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“…The DIC technique compares a series of digital images, for example, of the surface of a loaded specimen, and measures the displacements by matching the same pixels in consecutive photographs, before and after deformation. This technique, used in many research fields, has been widely and successfully employed in rock mechanics [51][52][53].…”

Section: Gradementioning

confidence: 99%

Preliminary Characterisation of an Italian Soft Rock with a Block-in-Matrix Fabric

et al. 2022

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Mélanges are heterogeneous geological deposits and represent the most widespread bimrock (block-in-matrix) formations. This paper presents the efforts undertaken to characterise an Italian mélange composed of a clayey-marly matrix enclosing strong calcareous blocks. Due to its low uniaxial compressive strength, this geomaterial can be classified as a soft rock. The weak nature of the marly matrix and its water sensitivity, as well as the presence of rock inclusions, made the collection and preparation of intact specimens extremely complex and time-consuming operations. The difficulties encountered during these phases are described in detail; the various non-conventional procedures considered and developed to overcome these problems are also presented. The potential of the solutions proposed lies in the fact that they can be conveniently applied to other soft rocks with a block-in-matrix internal arrangement, such as the Italian mélange. To characterise the Italian mélange, point load and uniaxial compressive tests were carried out. From the results of these tests, a conversion factor equal to 14 is proposed to correct the point load strength index in order to estimate the uniaxial compressive strength of soft rocks, such as the mélange under study. Moreover, to estimate local strains and the deformability of the geomaterial, the non-destructive digital image correlation technique was applied.

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“…The microstructural mechanisms that control the strain accommodation in gypsum have for long time interested the scientific world and are still not completely understood [12][13][14]. The coalescence of cracks in synthetic and natural gypsum samples have been successfully investigated by means of the visual analysis and comparison of photographic sequences [15][16][17][18][19]. However, this methodology cannot be directly applied to more complex loading conditions, when the sample is inserted in a visual opaque structure for the application of a confining pressure.…”

mentioning

confidence: 99%

Crack coalescence and strain accommodation in gypsum rock

Caselle

Bonetto

Costanzo

2020

Frattura Ed Integrità Strutturale

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The micro-mechanisms involved in the deformation of gypsum rock have for long time interested the scientific world and are still not completely understood. The present work proposes an experimental investigation of strain accommodation in gypsum rock, reporting data referred to uniaxial and triaxial stress conditions. The rock deformation was investigated with a multiscale approach, with the comparison of results from DIC and microstructural analyses, aiming to propose an interpretation of crack coalescence and strain accommodation in natural gypsum rock (i.e. branching selenite facies), focusing on the influence of textural and compositional layering on the mechanical response. The failure was observed to coalesce following an unstable step-wise process. With the increase of confining pressure, the material develops a structure of plastic accommodation of strain, favoured by the peculiar crystallographic structure of gypsum, with water molecules layered in the salt structure.

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Evolution of Local Strains Under Uniaxial Compression in an Anisotropic Gypsum Sample

Cited by 4 publications

References 12 publications

Preliminary Mineralogical Characterization of Branching Selenite Gypsum: New Insights for the Paleoenvironmental Reconstruction and Mechanical Characterization

Preliminary Mineralogical Characterization of Branching Selenite Gypsum: New Insights for the Paleoenvironmental Reconstruction and Mechanical Characterization

Preliminary Characterisation of an Italian Soft Rock with a Block-in-Matrix Fabric

Crack coalescence and strain accommodation in gypsum rock

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