1,720,986 research outputs found
Geological and numerical models as a tool to manage landslide risk: The Passo della Morte case study (UD, Italy)
No full textIn the northern Italian Alps, along the Tagliamento River valley (46°23'49" N, 12°42'51" E), a large deep-seated landslide affects a road tunnel near "Passo della Morte", along National Road 52 "Carnica". Several secondary phenomena are developing on the unstable slope, as rock block slides and shallow debris slides. This work focuses on the creation of a geological and numerical model able to simulate the displacements of two adjacent and partly superimposed shallow landslides, which are damaging the east entrance of the tunnel. In fact, field surveys and long-term monitoring allowed the geometries and the kinematics of the landslide bodies to be defined with great detail. In this phase, a numerical model is needed in order to evaluate the effectiveness of possible structural mitigation works. The complexity of the landslides dynamics and the different rates of activity suggest to set up a 3D model rather than a 2D one, using the commercial software FLAC3D. A helicopter-borne Light Detection And Ranging (LiDAR) survey allowed to rely on a 1 m Digital Terrain Model (DTM) for surface topography, while several boreholes equipped with inclinometers supported the definition of a 3D sliding surface. However, the high resolution of the input data collides with the necessity of reduce computational time to an acceptable level, thus an interpolation of the spatial data was almost compulsory. Anyhow, the calibrated model of the "Passo della Morte" landslides, obtained with filtered data, is the starting point for the simulation of different types of possible countermeasure works designed to mitigate landslide risk
Detecting Change of Patterns in Landslide Displacements Using Machine Learning, an Example Application
No full textMachine learning and signal processing can support the
definition of landslide alert/alarm systems based on
monitoring data. The possibility to rely on a straightfor-
ward and automatic procedure to identify hazardous
situations could be very useful for risk management and
decision makers. In this work, we propose a hierarchical
clustering algorithm to identify changes of pattern in the
displacements of monitored landslides. Our test site is a
large, active Deep-seated Gravitational Slope Deforma-
tion (DGSD) in which secondary movements provide
sediment for debris flows that threaten downstream
settlements. An Automated Total Station (ATS) has been
installed in 2012 to measure the three-dimensional
displacements of several benchmarks distributed on the
source area and to trigger alarms if superficial movements
potentially leading to collapses are detected. Results show
that the procedure allows to group benchmarks with
similar displacement patterns. The unsupervised defini-
tion of homogenous areas from a kinematic viewpoint
supports an unbiased geomorphological characterization
of the large landslide. Moreover, the method allows to
trigger alert warnings if some monitored points change
displacement pattern. The identification of possible
hazardous situation is performed without imposing fixed
and arbitrary thresholds and without calibration. The
recognition of areas with new types of activity supports
the definition of the sediment volumes available for
transport for the next debris flow event and assists the
definition of reliable risk scenarios
Backward automatic calibration for three-dimensional landslide models
Full text linkBack-analysis is broadly used for approaching geotechnical problems when monitoring data are available and information about the soils properties is of poor quality. For landslide stability assessment back-analysis calibration is usually carried out by time consuming trial-and-error procedure. This paper presents a new automatic Decision Support System that supports the selection of the soil parameters for three-dimensional models of landslides based on monitoring data. The method considering a pool of possible solutions, generated through permutation of soil parameters, selects the best ten configurations that are more congruent with the measured displacements. This reduces the operator biases while on the other hand allows the operator to control each step of the computation. The final selection of the preferred solution among the ten best-fitting solutions is carried out by an operator. The operator control is necessary as he may include in the final decision process all the qualitative elements that cannot be included in a qualitative analysis but nevertheless characterize a landslide dynamic as a whole epistemological subject, for example on the base of geomorphological evidence. A landslide located in Northeast Italy has been selected as example for showing the system potentiality. The proposed method is straightforward, scalable and robust and could be useful for researchers and practitioners
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
GEOLAB - Transnational Access project SHARP - Soil Heterogeneity for soil Amelioration in Road Projects
No full textThe SHARP - Soil Heterogeneity for soil Amelioration in Road Projects experiment proposes a novel approach to subgrade improvement: the strategic placement of gravel or other recycled aggregates in a layered configuration. This methodology aims to achieve a sufficient enhancement of the subgrade's mechanical properties, potentially eliminating the need for more resource-intensive and environmentally impactful techniques. The current research phase focuses on the evaluation of performance improvement in silt through the introduction of gravel layers via large-scale triaxial testing. Numerical simulations have already yielded promising results, highlighting the potential of this approach. However, the inherent size disparity between gravel and silt particles necessitates the use of large-scale testing equipment to accurately capture their composite behavior and avoid scale issues. Conventional triaxial equipment, typically limited to 10 cm diameter specimens, is inadequate for this purpose. The utilization of a large-scale triaxial apparatus facilitates the acquisition of reliable data directly applicable to real-world road and railway construction practices.
The traditional Terzaghi method for analyzing consolidation (settling) in soils is not accurate for layered soils with different compressibility characteristics. This is a well-established fact (Schiffman & Stein, 1970; Lee et al., 1992). Previous research (Huang & Griffiths, 2010) has also shown that using the Terzaghi method for layered soils in finite element modeling can lead to inaccurate results due to issues with flow continuity at the interfaces between layers. This highlights the importance of studying consolidation in layered soils, both for practical reasons (ensuring the proposed solution is viable) and to gain a deeper theoretical understanding (the heterogeneity effect on consolidating silty soil).
While numerical simulations have suggested that adding gravel layers to silty soil can significantly improve slope stability (Bossi et al., 2016), this needs experimental validation. Smaller lab specimens are not suitable due to the size difference between gravel and silt.
The test performed within the SHARP project aimed to investigate the effectiveness of a "patchy" gravel-in-silt mix on volumetric changes and shear strength. This approach aims to be practical for construction crews by allowing the gravel to be spread in lenses within the existing subgrade. This would simplify construction and ensure a minimum level of performance for the improved subgrade.
Ultimately, the goal is to use the data from these tests to assess the validity of using an "average friction angle" approach (Elkateb, 2003) for layered soils, considering the impact of the spatial distribution of the gravel layers. Numerical modeling can help answer these questions, but data for validation are necessary
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
Lithological variability of the Mortisa landslide body: Assessing geomorphological evolution and numerical modelling through a stochastic approach
No full textThe Mortisa landslide is located in the urban area of Cortina d'Ampezzo, north-east Italy. The landslide unit consists of three mudslides; the affected area is 3500 m long, stretching from 1750 to 1300 m a.s.l. The landslide has been investigated since 1998 as its track crosses a national route and some buildings have been severely damaged by the movements. Through radiocarbon dating it was possible to reconstruct the dynamic of the events that led to the formation of the present-day Mortisa slope. The landslide body is composed by interdigitated layers of gravel in a silty clay matrix originated from subsequent earth and debris flows events since the Lateglacial. To assess the stability conditions of the Mortisa landslide via numerical modelling it is crucial to consider the mechanical influence of the gravel lenses in the dynamic of the whole landslide body. However, their position is almost unknown inside the clay matrix with just some certain positions, where stratigraphic data are available. Therefore, in order to calibrate the model on the monitoring data through back analysis, a new procedure has been implemented. A new code permits to generate stochastically several soil configurations which are automatically elaborated by the commercial software FLAC. The results are organized and filtered based on the monitoring data, hence it is possible to select the model that fits the data best. In this way it it possible to obtain a sound back-analysis model of the Mortisa landslide, to be used in order to design countermeasure works and mitigate the risk associated with the phenomenon
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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