1,721,349 research outputs found
Physical layer aware open optical networking
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Multiphysical Testing of Soils and Shales
No full textSignificant advancements in the experimental analysis of soils and shales have been achieved during the last few decades. Outstanding progress in the field has led to the theoretical development of geomechanical theories and important engineering applications. This book provides the reader with an overview of recent advances in a variety of advanced experimental techniques and results for the analysis of the behaviour of geomaterials under multiphysical testing conditions. Modern trends in experimental geomechanics for soils and shales are discussed, including testing materials in variably saturated conditions, non-isothermal experiments, micro-scale investigations and image analysis techniques. Six theme papers from leading researchers in experimental geomechanics are also included. This book is intended for postgraduate students, researchers and practitioners in fields where multiphysical testing of soils and shales plays a fundamental role, such as unsaturated soil and rock mechanics, petroleum engineering, nuclear waste storage engineering, unconventional energy resources and CO2 geological sequestration
Using Clustering to Improve the Structure of Natural Language Requirements Documents
No full text[Context and motivation] System requirements are normally provided in the form of natural language documents. Such documents need to be properly structured, in order to ease the overall uptake of the requirements by the readers of the document. A structure that allows a proper understanding of a requirements document shall satisfy two main quality attributes: (i) requirements relatedness: each requirement is conceptually connected with the requirements in the same section; (ii) sections independence: each section is conceptually separated from the others. [Question/Problem] Automatically identifying the parts of the document that lack requirements relatedness and sections independence may help improve the document structure. [Principal idea/results] To this end, we define a novel clustering algorithm named Sliding Head-Tail Component (S-HTC). The algorithm groups together similar requirements that are contiguous in the requirements document. We claim that such algorithm allows discovering the structure of the document in the way it is perceived by the reader. If the structure originally provided by the document does not match the structure discovered by the algorithm, hints are given to identify the parts of the document that lack requirements relatedness and sections independence. [Contribution] We evaluate the effectiveness of the algorithm with a pilot test on a requirements standard of the railway domain (583 requirements)
Laboratory Study on the Volumetric Response of Gas Shale Samples with Controlled Pore Fluid Pressures
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The permeable concrete: A low energy consumption solution for deep draining trenches
No full textThe reduction of pore water pressures is one of the very effective measures to improve the stability conditions of marginally stable water-bearing slopes or to stabilise landslides. For this purpose the trench drains have been used long since. Like filling material of deep trenches the permeable concrete can be effectively employed. It presents relatively high hydraulic conductivity, filtering capacity in order to prevent the internal erosion of the soil in which the trench drain is installed, enough residual hydraulic conductivity after possible clogging, sufficient shear strength after a short curing time to avoid the instabilisation of adjacent previously built panels or piles. Results of a laboratory experimental research on the mix-design, hydraulic conductivity and strength of pervious concrete are reported in the paper, proving that proper mix-design can be devised meeting the above requirements. Permeable concrete is a very poor material and a low energy consumption solution for slope stabilisation
Microstructure and shear strength evolution of a lime-treated clay for use in road construction
Full text linkThe results of a comprehensive experimental programme are presented for assessing the long-term microstructural modifications and evaluating the effects of microstructural rearrangement on the stress–strain behaviour of a lime-treated high-plasticity clay for road embankments. The stress–strain behaviour at different lime content and curing time was investigated by means of direct shear tests; microstructural analyses were carried out combining Scanning Electron Microscope observations and Mercury Intrusion Porosimetry tests. The results show that the stress–strain behaviour of treated clay is strongly dilatant with a high peak of strength, which increases with time and lime content. Furthermore, a hyperbolic function may be used for predicting the increase in strength at the end of the stabilisation process. Microstructural analysis shows that the treatment induces a redistribution of the porosity between macro- and micropores and an increase in matric suction, associated to a low reduction of water content and to aggregates shrinkage. This behaviour is affected by lime content and curing time since it results from the formation of the pozzolanic compounds on the surface of clay aggregates that induces both a bonding between hardened clay aggregates and an increase of their interlocking degree, with a consequent increase in the shear strength
Water retention behaviour of compacted and reconstituted scaly clays
Full text linkThe paper presents the results of an experimental research devoted to investigate the response to
suction variations of a scaly clay in compacted and reconstituted conditions. Different experimental
techniques (axis translation, vapour equilibrium, dew point psychrometer suction measurements) were
combined in order to explore the water retention properties in a wide suction range (0 ÷ 110 MPa).
Experimental results allowed to define the water retention domains for a constant reference void ratio,
highlighting the significant role of the microstructure on the response of the investigated clays. In particular,
the collected results showed that in the low-medium suction range, the peculiar microstructural features give
to the reconstituted clay a better retention capability than the compacted clay. However, the increasing
suction induces a significative volumetric shrinkage on the saturated reconstituted clay, especially when the
latter is initially normally consolidated. On the other hand, quite similar retention properties were
recognized in the high suction range
Experimental investigations of the soil-concrete interface: physical mechanisms, cyclic mobilisation and behaviour at different temperatures
No full textBehaviour of the pile-soil interface is important to correctly predict the response of floating piles in terms of displacement and lateral friction. Regarding energy piles, which couple the structural roles of deep foundations with the principle of shallow geothermal energy, the response of pile-soil interfaces is influenced by seasonal and daily cyclic thermal variations. Accordingly, the goal of this paper is to experimentally investigate the response of the pile-soil interface at different temperatures. This experimental campaign aims to analyse (i) the cyclic mobilization of the shear strength of the soil-pile interface that is induced by thermal deformation of the pile and (ii) the direct influence of temperature variations on the soil and soil-pile interface behaviour. In this study, a direct shear device was developed and calibrated for nonisothermal soil-structure interface testing. It appears that the sand-concrete interface was affected by cyclic degradation but not affected directly by temperature. Conversely, the response of the clay-concrete interface changed at different temperatures, showing an increase of strength with increasing temperature, presumably due to the effects of temperature on clay deformation
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