1,720,963 research outputs found
From Hydrogeological Hazard Identification To Risk Assessment In Tunnelling: An Example In Northern Italy
No full textHydrogeological hazards are very common when dealing with underground excavations, and they can bring about a damage both for the tunnel (e.g., tunnel inflow) and for the environment (e.g., water resource depletion). The paper proposes an example of the contribution of hydrogeology to risk management in tunnelling. In particular, the two following issues are addressed: how tunnel inflow can be assessed, and how its impact on water resources can be quantified. These issues are discussed based on the state of the art and with reference to an applicative example located northern Italy and excavated in sedimentary rocks at medium depth. A framework has been defined in order to: (1) identify the tunnel stretches affected by potential hydrogeological hazard, (2) quantify the tunnel inflow, (3) evaluate the changes in the hydrogeological balance and therefore assess the environmental impact. As far as tunnel inflow, different approaches have been used (empirical, analytical and numerical), pointing out that empirical methods are easy to use, but they can give only a qualitative evaluation of tunnel inflow; on their turn, analytical formulas provide a quantitative estimation, but results are often inadequate; numerical models can be useful for managing complex hydrogeological problems, but their results depend on the available input data. For the case study, monitoring data were compared to the values forecasted through the different approaches, obtaining different errors. Based on tunnel inflow rates, the changes in water balance can be evaluated in order to assess the environmental hydrogeological risk arising from tunnelling. The assessment was carried out for the case study with a stochastic approach, that involves the definition of critical thresholds
A new rating system for hydrogeological risk management along railway infrastructures in Prealpine zone (northern Italy)
Full text linkRailway infrastructures in mountain areas often develop along hillslopes affected by geomorphological and hydrogeological processes which might lead hazardous events. Therefore, specific tools for risk analysis and management are required. This paper develops a new rating system (Railway Hydrogeological Management System, RHMS), based on a heuristic method which considers the susceptibility to different types of slope instabilities, as well as the peculiar features affecting the railway vulnerability. The proposed method introduces an iterative approach for the risk assessment, based on the definition of acceptability thresholds for the residual risk. The application of this method to a test area pointed out its feasibility, as well as its operational capability to identify the critical sections of the infrastructure, in which protection or mitigation measures are needed in order to reduce the risk
Analisi critica del metodo RHRS utilizzato per la valutazione della pericolosità dei versanti in roccia ubicati lungo le vie di comunicazione
No full textPareti rocciose instabili e strade: un sistema di valutazione delle priorità di intervento.
No full textConceptual and numerical modelling for hydrogeological hazard assessment in the UNESCO site of Castelseprio (Northern Italy)
No full textThis paper deals with the evaluation of the hydrogeological hazard in the archaeological site of Castelseprio (northern Italy). Based on the geological, hydrogeological and geomorphological setting of the site, the failure modes and their causative factors were identified, and a proper conceptual model was reconstructed, identifying piping processes as the main phenomena ruling the slopes evolution and the landslides triggering. Afterwards, the hydrogeological hazard was assessed applying numerical modelling both in 2D and in 3D. In particular, the 2D analyses were aimed at simulating the triggering phenomena leading to instability, with particular reference to the influence of piping initiation and propagation. Numerical results in 2D showed a dependence of the stability conditions on the rainfall intensity, whose increase brings about a significant widening of the zones prone to piping. Based on the results of the 2D simulations, a 3D model was implemented in order to evaluate the stability conditions in the different zones of the study area. The results of the 3D simulations allowed mapping the hydrogeological hazard and identifying the best practices for the future development of the UNESCO site, in order to guarantee its unity as well as its safety
Stochastic modelling of groundwater flow for hazard assessment along the underground infrastructures in Milan (northern Italy)
No full textThe paper discusses the hydrogeological hazard for the underground infrastructures caused by the rise of the groundwater level observed in Milan (Italy). The study is the prosecution of a previous paper (Gattinoni and Scesi, “The groundwater rise in the urban area of Milan (Italy) and its interactions with underground structures and infrastructures” TUST 62(2017): 103–114), that analysed the phenomenon through a deterministic groundwater flow numerical model, pointing out the related potential hazards and the possible mitigation solutions. Starting from the reconstruction of the phenomenon previously obtained, in the present paper the 3D numerical model of the groundwater flow was turned out into a stochastic model in order to assess the hydrogeological hazard (in probabilistic terms) for the underground infrastructures. At this aim, different scenarios of the aquifer system were considered: (1) the probability distribution of the recharge describing the present day conditions; (2) the decrease in the pumping rate of wells expected in the next 15 years; (3) an increase of the regional groundwater table, based on the projection of the rising trend for the next 15 years. Modelling results have pointed out a significant increase in water level by 5 m in the next 15 years, depending on the scenarios taken into account. The water table rise interests mainly the north-western zone of the study area, and it affects the metro tunnels located in the centre of the city. Therefore, some metro tunnels will be flooded (or even submerged) with different occurrence probability. The flooding hazard increases with the increasing depth of the infrastructures, especially in the northern-central zone of the study area
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
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