1,720,953 research outputs found
Finite element modeling of pile-soil interaction: effects of installation and response in sloping ground
No full textPiles are installed in many civil engineering projects on the level ground and near the slopes in vertical and inclined directions. While axial capacity is the primary concern in foundation design, the effects of lateral load due to ground movement are equally important in many cases, such as slope stabilization by piles and the impact of lateral spreading.
Displacement piles are generally installed by jacking or diving. During installation, a large volume of soil displaces around the pile, which could cause soil disturbance and thus affect the subsequent load-carrying capacity. Modeling the pile installation is a challenging task, especially when installed in sensitive clays. The contractive response and structural breakdown during shearing cause strain softening and develop a significant excess pore water pressure that could reduce the effective stress of the soil around the pile close to zero for high sensitive clays. The soil disturbance and penetration resistance, especially the skin friction, highly depend on softening and excess pore water pressure. The rate of shearing could also affect the soil strength and penetration behaviour. In the present study, the installation of the pile in sensitive clays are simulated for undrained condition. Mathematical models for strain-softening and strain-rate effects on the undrained shear strength are implemented using user subroutines. A comparison with the results of a field test conducted previously in Québec, Canada, shows that the present numerical technique can successfully simulate the installation process. The simulation results also show that the simplified approaches (e.g., cavity expansion or strain path methods) cannot model some key aspects of pile installation in highly sensitive clay. For jacking, the shear strength of soil in a small zone around the pile reduces to a small value due to strain softening, and the disturbed soil flows primarily through this narrow zone when the penetration is continued to a larger depth. The plastic
shear strain develops over a larger area for low sensitive clays, but its magnitude near the pile is higher in high sensitive clays.
The penetration due to impact driving is different from that in jacking. Near the ground surface, each blow results in continuous penetration, although the rate of penetration is negligible at the end. However, at a deeper condition, the hammer impact results in penetration first, and then the pile rebounds some distance. The strain rate effects on undrained shear strength play a significant role in impact driving, as compared to jacking because the rate of penetration is higher during impact, which increases the mobilized shear strength near the pile surface, and therefore soil flow occurs through a relatively larger area. For a given depth of penetration at the end of a blow, the stress distribution around the pile in driving and jacking is comparable.
For a sloping ground, the installation of a pile could cause the retrogressive failure of the slope, as reported in some studies. It is extremely difficult to conclude whether such failure was occurred only due to pile driving or a combination of other factors. Two retrogressive landslide cases studies are presented, where, in the first one, the failure of a sensitive clay slope was triggered by pile driving and, in the second one, landslide might have been triggered by toe erosion. However, the post-slide investigations show similar failure patterns, which implies that, although the soil type and triggering mechanisms are different, simulations can be performed using the same numerical technique.
In the sloping ground, piles might be located at different locations of the slope—for example, near the toe/crest or on the slope. When slope failure occurs, the upper part of the pile in the sliding mass experience lateral load. Similar loading occurs in lateral spreading. Large deformation FE analyses are performed to calculate the force acting on the pile due to ground movement. The effects of arching on the lateral force in relation to soil behaviour and pile spacing are examined.Includes bibliographical reference
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Large-strain finite element analyses of a retrogressive landslide triggered by pile driving in sensitive clays: The Case of the 1978 Rigaud landslide in Québec
Get PDFA retrogressive landslide triggered by pile driving in sensitive clays in Rigaud, Quebec, is analyzed. The article presents the landslide characteristics, post-failure assessments, and potential failure mechanisms. To gain deeper insights into the triggering and propagation of failure, large-strain finite element (FE) modelling was conducted using a Eulerian-based FE approach. The FE simulations reveal that pile installation can induce localized shear band formation, ultimately leading to a large-scale landslide without the need for additional external loading. Key factors influencing the failure pattern include soil stratification, sensitivity, and the rate of post-peak shear strength degradation. The numerical modelling effectively replicates the observed field behaviour of the landslide, capturing crucial aspects such as retrogression distance, failure pattern, and the downslope displacement of failed soil masses. Although the landslide involved complex three dimensional effects and triggering conditions, the current two-dimensional large-strain FE simulations under plane strain conditions provide valuable insights into the underlying progressive failure mechanisms—insights that cannot be obtained using traditional limit equilibrium and conventional FE analyses. These findings underscore the significant role of pile driving in initiating landslides in sensitive clays and highlight the necessity of advanced numerical approaches to accurately predict and mitigate such failures.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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