1,720,972 research outputs found
Preliminary Numerical Simulation of Centrifuge Tests on Tunnel-Building Interaction in Liquefiable Soil
No full textThis paper shows the results of preliminary numerical analyses performed to simulate centrifuge tests that will be carried out for the project STILUS within the framework of the European funded network SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The aim of the project is to investigate the problem of tunnel-structure interaction in liquefiable soil through a series of centrifuge tests and to assess an effective mitigation technique. Two models will be tested in centrifuge, in the first one only the tunnel is modelled while in the second one a simplified structure on strip foundations is added. In order to analyze a cut-and-cover tunnel in an urban environment a rectangular section has been assumed. The tests were simulated by means of Plaxis 2D and the soil was characterized by PM4Sand model. The results were evaluated in terms of pore pressure build up, accelerations and settlements. The distribution of excess pore pressure induced around the tunnel and the building basement may also be useful to identify where mitigation techniques that may locally reduce pore-pressure build-up would be most effective against the effects of soil liquefaction and should be implemented in the forthcoming tests
Experimental and Numerical Investigation on the Effectiveness of Polymeric Barriers to Mitigate Vibrations
No full textThe results of an experimental activity aimed at investigating the ability of barriers made of a soft polymer [Super Absorbing Polymer (SAP)] to reduce the impact of ground vibrations on existing structures are described in this paper. A series of field tests was performed to examine the screening effectiveness of such barriers. Perturbing shear waves were generated using a vibrant source with controlled force and frequency. Field measurements of wave propagation with and without the barrier show the reduction of amplitude in several points of interest, caused by the extremely low shear stiffness of SAP. Two different geometrical configurations of the barriers were adopted in the field: one having the classical vertical trench shape, and the other with a less common shape of an upside-down pyramid. A FEM model was built and numerical analyses were performed and validated against the experimental results. After validation, the numerical analyses were also used to add further information on the behaviour of barriers of different shape. © 2019, Springer Nature Switzerland AG
Numerical modelling of the effect of horizontal drains in centrifuge tests on soil-structure interaction in liquefiable soils
No full textThe research presented herein was carried out in the framework of the H2020 LIQUEFACT project (http://www.LIQUEFACT.eu/). This paper presents the results of a set of numerical analyses performed to study the soil-structure interaction in presence of a liquefiable soil. In the first part of the paper, the attention was focused on the ability of some advanced soil constitutive models to simulate the centrifuge tests carried out within the project. Two finite element codes, Plaxis 2D and OpenSees, were used for the computations. The results were analysed in terms of accelerations, displacements and pore pressures build up. In the second part of the paper the effects of the introduction of horizontal drains, as mitigation techniques against liquefaction, were shown and discussed in terms of their ability in reducing pore pressure build-up and building settlement. All the numerical predictions confirmed the experimental evidence that horizontal drains are able to reduce the excess pore pressure during shaking and the structural settlement. The amount of reduction depends on the water boundary condition at surface: a free seepage surface generally allowed a larger mitigation than where the liquefiable layer was topped by clay
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A new frontier of BIM process: Geotechnical BIM. Atti del XVII European Conference on Soil Mechanics and Geotechnical Engineering
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