1,720,959 research outputs found
Microstructural Analyses of a Stabilized Sand by a Deep-Mixing Method
No full textThe deep-mixing method (DMM) involves the mechanical mixing of in-situ soil with various stabilizing binders, which chemically react with the soil or the groundwater. Microstructural analyses are valuable tools to support ordinary geotechnical laboratory tests to assess the effectiveness of ground improvement works. This paper presents the results of microstructural analyses on in-situ retrieved samples and laboratory mixed specimens related to an actual deep mixing job site. Mercury porosimetry and X-ray computed Microtomography were used to determine the total porosity and to characterize the pore network of both types of samples. The results of the analyses allowed a qualitative understanding of the degree of mixing of the soil with the binder suspension under laboratory and field conditions. Additionally, an original correlation between total porosity and unconfined compressive strength was obtained based on the experimental data for cement-treated sandy soils at long curing time
Comportamento dei micropali in terreni eterogenei
No full textNegli ultimi decenni l’impiego di micropali, non solo come elemento di fondazione ma anche come elemento di consolidamento e rinforzo, è rapidamente aumentato. Ciò è dovuto alla relativa semplicità costruttiva ed esecutiva dei micropali, che richiede attrezzature di dimensioni contenute, agevolmente trasportabili in luoghi difficilmente accessibili.
Molto spesso nelle zone montagnose dell’Arco Alpino, dove i terreni sono spesso costituiti da una miscela eterogenea di ghiaie, sabbie con limi e argille inglobanti blocchi di roccia di dimensioni ragguardevoli, i micropali sono una delle poche tecnologie utilizzabili per realizzare fondazioni di fabbricati, paratie ancorate, sottofondazioni di opere di sostegno o per consolidare versanti in frana.
Tali terreni sono spesso difficili da caratterizzare da un punto di vista meccanico, a causa della impossibilità di condurre prove in sito, con l’eccezione delle SPT, o eseguire un campionamento indisturbato.
In queste condizioni la progettazione dei micropali è affetta da un margine di errore relativamente elevato, nonostante i miglioramenti introdotti anche dalla recente normativa italiana per la progettazione dei pali.
In relazione a ciò, l’Università di Padova ha recentemente avviato una collaborazione con Veneto Strade Spa, per realizzare due siti sperimentali, nei quali condurre prove di carico a compressione e trazione su micropali realizzati con la metodologia tradizionale di colatura del fusto. Le formazioni interessate sono quelle caratteristiche di molti depositi delle Alpi Bellunesi, nei quali la componente granulare è spesso prevalente.
Sulla base dei risultati ottenuti dai siti sperimentali, lo studio esamina criticamente le ipotesi e le procedure assunte nella progettazione dei micropali in terreni eterogenei. In particolare si cercherà di simulare analiticamente il comportamento del micropalo singolo, al fine di calibrare un metodo di progetto in accordo con la normativa vigente, da applicare in situazioni caratteristiche delle Alpi Bellunesi
Microstructural and Mineralogical Evaluation of the Effectiveness of Mixing Treatments in Stabilized Clays
No full textThis paper shows and discusses the results of a comprehensive mineralogical and microstructural investigation carried out on several samples collected from diaphragm walls obtained treating a deposit of overconsolidated clay with the cutter soil mixing (CSM) technology, one of the most recent methods for deep mixing. To this purpose, scanning electron microscopy, X-ray powder diffraction analysis, mercury intrusion porosimetry, and X-ray computed micro-tomography were extensively used to measure soil properties at the micro-scale. In addition, unconfined compression tests and permeability tests were conducted to evaluate the effectiveness of CSM also at the macro-scale. The capability of CSM to treat cohesive soils seems to be confirmed by the experimental investigation carried out so far, considering, particularly, the degree of mixture homogeneity achieved at the end of the mixing procedure, together with the growth of several hydration products in the cemented matrix
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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