Search results for "Suction."
showing 10 items of 70 documents
Experimental analysis of the water retention behaviour of shales
2014
Shales are among the most commonly considered geomaterials in current energy-related geomechanical investigations, as they are involved in engineering applications such as the unconventional extraction of natural gas, CO2 sequestration and nuclear waste geological storage. A deep understanding of their behaviour with regard to variations in the degree of saturation is of primary significance for such applications. With the aim to establish a sound protocol for shale retention behaviour analysis, this paper presents an advanced experimental methodology that takes into account the specificities of shales such as small pore size dimensions and the large variations in water potential to be appl…
Shot-clay MX-80 bentonite: An assessment of the hydro-mechanical behaviour
2014
This study presents the results of an experimental study conducted to characterise the hydro-mechanical behaviour of shot-clay MX-80 bentonite. In the shot-clay process, granular bentonite was mixed continuously with water and shot on the walls of a tunnel section at the Grimsel Underground Research Laboratory (URL), in Switzerland. The shot-clay was placed to create a layer of bentonite in direct contact with the host rock to avoid preferential water and/or gas flow along the tunnel wall. Samples for an experimental programme were collected during the shooting. The index properties, microstructural features, swelling potential and water retention properties of the shot-clay were analysed. …
Anisotropic Volumetric Response of Shales upon Suction Changes
2016
Anisotropic fabric and volumetric response to suction changes represent two main features of shales, which are involved in several engineering applications. However, a comprehensive understanding of the interaction between these two aspects is still missing. The present work aims to provide a detailed analysis of the coupling between the water retention capacity of shales and their anisotropic behaviour through an advanced experimental methodology. Among the various tested facies of the Opalinus Clay Shale (Mont Terri, Switzerland), the results from the shaly facies are presented in this study. The behaviour of the material is characterized by swelling and shrinkage respectively upon wettin…
External Volume Expansion Increases Subcutaneous Thickness, Cell Proliferation, and Vascular Remodeling in a Murine Model
2012
Background Fat grafting is a powerful tool for soft-tissue reconstruction; however, the science behind recipient bed preparation has not been thoroughly explored. External volume expansion using suction before fat grafting has been used clinically to improve reliability and consistency of graft survival. The authors developed a murine model to investigate the underlying mechanism of external volume expansion. Methods The authors created an external volume expansion device using a soft-silicone dome connected to a vacuum source (25 mmHg) to treat the dorsum of mice, and the response was compared with treatment with an occlusive dressing. Treated areas were monitored with magnetic resonance i…
Anisotropic volumetric behaviour of Opalinus clay shale upon suction variation
2016
Opalinus clay shale is under consideration to serve as the host geomaterial for the underground storage of nuclear waste in Switzerland. Water retention behaviour and anisotropic behaviour represent two main features of this geomaterial; however, a comprehensive understanding of the interaction between these two features is still lacking. This paper aims to provide a detailed experimental analysis of the coupling between the water retention capacity and the anisotropic behaviour of two facies (shaly and sandy) of the Opalinus clay shale. The response of the tested geomaterials is characterised by an unequal swelling and shrinkage response in directions parallel and perpendicular to the bed…
The Role of Anisotropy on the Volumetric Behaviour of Opalinus Clay upon Suction Change
2017
An experimental investigation to analyse the anisotropic volumetric response of shaly and sandy facies of Opalinus Clay upon suction variations is presented. Obtained results demonstrate the different behaviour of the tested facies to a wetting-drying cycle. The shaly facies exhibits higher water retention capacity and stronger volumetric response than the sandy facies. Anisotropic response is experienced by both facies with the strain perpendicular to bedding higher than in the parallel direction. The sandy facies exhibits a more pronounced anisotropic behaviour in particular during the drying phase. A detailed analysis of the response in the two directions with respect to the bedding orie…
Shear Strength of a Compacted Scaly Clay from Suction-Controlled Triaxial Tests
2012
The paper presents the results of an experimental research aimed at investigating the shear strength characteristics of an unsaturated compacted scaly clay. Shear strength was investigated by suction-controlled triaxial compression tests on dynamically compacted samples. Collected results point out that suction effects on stiffness and shear strength can be very different for suction values applied lower or greater than air entry value (AEV), corresponding to the material void ratio.
X-ray Computed Tomography for Capillary Collapse of Loose Unsaturated Sand
2016
Abstract The collapse of unsaturated soils consists of the reduction in volume upon wetting at constant total stress. Several studies at the macro scale outline the influence of initial void ratio, confining pressure and matric suction on the onset of collapse of standard laboratory specimens. Conversely, few observations at the micro scale are available in the literature, although the influence of the particles arrangement and intergranular bonding has been formerly supposed. The collapse of fine sand derived by a pyroclastic soil of Southern Italy is investigated in this paper at the microscale using the X-ray Computed Tomography. The experimental procedure, formerly tested on similar pyr…
Evaluation of cliff recession in the Valle dei Templi in Agrigento (Sicily)
2015
Abstract The sacral complex of the Valle dei Templi in Agrigento, added in the UNESCO Heritage Site List, stands over the crest of a rigid calcarenite cuesta, which overlies a layer of partially saturated (S = 6–12%) carbonate sand. In turn, the sand stratum lies on a thick stratum of clays. The environment is highly prone to landslides as highlighted by several previous studies that identify the undermining of slopes and the discontinuity pattern, occurred in the late Neotectonic phase, as causes of cliff failure. For wider and less exposed areas, where the undermining local instabilities can be present because of the specific morphology of the site, a recent research has proposed a new in…
Effect of Fibrin Sealant on Seroma Formation Post-Incisional Hernia Repair
2020
Background: Development of seroma after incisional hernia repair is a common complication. Our study aims to compare the outcomes of sublay incisional hernia repairs with or without spray instillation of fibrin glue. Methods: We enrolled fifty patients undergoing incisional hernia repair. In all patients a suction drain was placed in the subcutaneous space. In one group (FG) 4 ml fibrin glue was instilled in the subcutaneous space. In the control group (C) patients did not receive any prevention measure. Wounds fluids were collected on post-operative day 1 (POD) and once daily until drain removal. All patients were followed up by ultrasound on POD 15, 20, 40, 60. Results: Drain fluid produc…