“…Similar phenomena with comparable compacted zones have been observed in very porous refractory material (i.e., 65 vol% porosity [14]), porous articial rock [17] and aluminum foam [19,20]. Recently the same observations were 12 reported on porous plaster [30] and cemented carbide [29].…”
Section: Mesoscopic Observationssupporting
confidence: 78%
“…A similar mechanism was observed in metal foams [20,19], as well as porous rocks [14,17,18], porous sintered alumina used as catalyst carrier [24], ceramic matrix composites [25] and high porosity gypsum [23,30,41,26,27].…”
Section: Discussionsupporting
confidence: 60%
“…A similar dependence was obtained for porous rocks [17], cemented carbide [29] and plaster [30,27]. The aim of the following sections is to explain the (linear) macroscopic load vs. depth penetration response.…”
supporting
confidence: 57%
“…Some relevant references were devoted to the indentation of porous rocks [14,17,18]. Leite and Ferland [17] conducted spherical indentation on articial rocks consisting of mixture of industrial gypsum, sand, water and polystyrene spheres. The tested materials had a porosity ranging between 44 and 68 vol%.…”
“…Similar phenomena with comparable compacted zones have been observed in very porous refractory material (i.e., 65 vol% porosity [14]), porous articial rock [17] and aluminum foam [19,20]. Recently the same observations were 12 reported on porous plaster [30] and cemented carbide [29].…”
Section: Mesoscopic Observationssupporting
confidence: 78%
“…A similar mechanism was observed in metal foams [20,19], as well as porous rocks [14,17,18], porous sintered alumina used as catalyst carrier [24], ceramic matrix composites [25] and high porosity gypsum [23,30,41,26,27].…”
Section: Discussionsupporting
confidence: 60%
“…A similar dependence was obtained for porous rocks [17], cemented carbide [29] and plaster [30,27]. The aim of the following sections is to explain the (linear) macroscopic load vs. depth penetration response.…”
supporting
confidence: 57%
“…Some relevant references were devoted to the indentation of porous rocks [14,17,18]. Leite and Ferland [17] conducted spherical indentation on articial rocks consisting of mixture of industrial gypsum, sand, water and polystyrene spheres. The tested materials had a porosity ranging between 44 and 68 vol%.…”
“…Another application of indentation tests on rocks is the estimation of material properties by means of inverse analysis. In [17], the authors propose an analytic way of estimating the Young's modulus and the uniaxial compressive strength of artificial porous rocks. Complete inverse analysis using finite element simulations have also been investigated like in [26], and more recently to estimate the Drucker-Prager parameters of a sandstone, see [19].…”
The unsaturated poromechanical behavior of Callovo-Oxfordian argillite (also referred to as Meuse/ Haute-Marne argillite) is analyzed by means of indentation tests at different hygrometries. Numerical simulations carried out with a finite element code are then used to simulate flat punch indentation tests at different controlled hygrometries. The numerical response F(h) is compared to experimental data in order to estimate the drained Young's modulus E and the internal friction angle U (at high confinement) by means of a back analysis. A linear decrease in the drained Young's modulus and quasi-constant values of the internal friction angle are observed when the relative humidity ranges. Some predictions of the model are also presented to quantify the activation of hydraulic phenomena. Indeed, the maximal variation of the saturation and porosity relative to the initial state of the specimen are lower than 10% and 8%, respectively.
A microindentation scanner is constructed that measures the spatial fluctuation in the elastic properties of natural rocks. This novel instrument performs automated indentation tests on the surface of a rock slab and outputs 2‐D maps of the indentation modulus at submillimeter resolution. Maps obtained for clean, well‐consolidated, sandstone are presented and demonstrate the capabilities of the instrument. We observe that the elastic structure of sandstones correlates well with their visual appearance. Further, we show that the probability distribution of the indentation modulus fluctuations across the slab surfaces can be modeled using a lognormal probability density function. To illustrate possible use of the data obtained with the microindentation scanner, we use roughly 10 cm × 10 cm scans with millimeter resolution over four sandstone planar slabs to numerically compute the overall drained elastic moduli for each sandstone sample. We show that such numerically computed moduli are well modeled using the multicomponent form of the Hashin‐Shtrikman lower bound that employs the observed lognormal probability distribution for the mesoscopic‐scale moduli (the geometric mean works almost the same). We also compute the seismic attenuation versus frequency associated with wave‐induced fluid flow between the heterogeneities in the scanned sandstones and observe relatively small values for the inverse quality factor (Q−1<10−2) in the seismic frequency band 102 Hz
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