The zero-stress state of the mucosa-submucosa and two muscle esophageal layers has been delineated, but their multi-axial response has not, because muscle dissection may not leave tubular specimens intact for inflation/extension testing. The histomechanical behavior of the three-layered porcine esophagus was investigated in this study, through light microscopic examination and uniaxial tension, with two-dimensional strain measurement in pairs of orthogonally oriented specimens. The two-dimensional Fung-type strain-energy function described suitably the pseudo-elastic tissue response, affording faithful simulations to our data. Differences in the scleroprotein content and configuration were identified as a function of layer, topography, and orientation, substantiating the macromechanical differences found. In view of the failure and optimized material parameters, the mucosa-submucosa was stronger and stiffer than muscle, associating it with a higher collagen content. A notable topographical distribution was apparent, with data for the abdominal region differentiated from that for the cervical region, owing to the existence of inner muscle with a circumferential arrangement and of outer muscle with a longitudinal arrangement in the former region, and of both muscle layers with oblique arrangement in the latter region, with thoracic esophagus being a transition zone. Tissue from the mucosa-submucosa was stronger and stiffer longitudinally, relating with a preferential collagen reinforcement along that axis, but more extensible in the orthogonal axis.
The Callovo Oxfordian clay-rock (COx) is studied in France for the disposal of radioactive waste, because of its extremely low permeability. This host rock is governed by a hydromechanical coupling of high complexity. This paper presents an experimental study into the mechanisms of water uptake in small, unconfined, prismatic specimens of COx, motivated by the comprehension of cracking observed during concrete/COx interface sample preparation. Water uptake is monitored using both x-ray tomography and neutron radiography, the combination of these imaging techniques allowing material deformation and water arrival to be quantified respectively. Given the speed of water entry and crack propagation, relatively fast imaging is required: 5 minute x-ray tomographies and ten-second neutron radiographies are used. In this study, pairs of similar COx samples from the same core are tested separately with each imaging technique. Two different orientations with respect to the core are also investigated. Analysis of the resulting images yields with micro-and macro-scale insights into hydro-mechanical mechanisms to be obtained. This allows the cracking to be interpreted as a rapid breakdown in capillary suction (supposed large both to drying and rebound from in-situ stress state) due to water arrival, which in turn causes a loss of effective stress, allowing cracks to propagate with ease, which in turn deliver water further into the material.
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