1,720,970 research outputs found
Thermo-physical and geo-mechanical characterization of faulted carbonate rock masses (Valdieri, Italy)
Full text linkWater in rock masses is a key factor in geo-mechanics, hydrogeology, mining, geo-thermics, and more. It is relevant in interpreting rock mass behavior (e.g., water-rock interaction or slope stability), as well as in defining heat transfer mechanisms. Pointing out the contribution of secondary porosity in increasing advective heat transfer instead of the conduction phenomenon, this study aims to highlight a different thermal response of sound rocks and faulted zones. Moreover, it provides some methodological suggestions to minimize environment disturbance in data collection and a robust interpretation of the results. An interesting outcrop was identified in a carbonate quarry near Valdieri (north-west Italian Alps): it was studied coupling a geo-mechanical and a thermo-physical approach. In particular, geo-mechanical and photogrammetric surveys, InfraRed Thermography (IRT), and Thermal Conductivity (TC) measurements were conducted. The rationale of the research is based on the fact that, when a substantial temperature difference between flowing groundwater and rocks was detected, IRT can reveal information about geo-mechanical and hydrogeological properties of the rock masses such as a degree of fracturing and joint interconnection. A comparative field and laboratory analysis using different devices enabled a more detailed insight providing values in both dry and wet conditions. A different thermal response was highlighted for the cataclastic zone as well. IRT results showed an evident inverse relationship among the number of joints per meter and the detected surface temperature. This is probably caused by the higher water flow within the cataclastic fault zone. Moreover, low fractured portions of the rock mass presented higher cooling rates and conducted heat far more than those with poor geo-mechanical characteristics (difference up to 40%). A negligible ratio between wet and dried thermal conductivity (about 1%) was also detected in lab measurements, which confirmed that primary porosity is not usually relevant in influencing thermal properties of the sound rock
Landslide on glaciers: an example from Western Alps (Cogne - Italy)
No full textIn the warm summer of 2017, a landslide failed from the south-east side of the Col des Clochettes on the top of the underlying Trajo Glacier. The study area is at an elevation of about 3500 m a.s.l. in the Gran Paradiso Massif and can be hardly reached by walking from Cogne (Aosta Valley, NW Italy). Studies conducted by field surveys, photogrammetry (structure from motion) and satellite images analysis, integrated with the evaluation of data from meteorological stations have been used to reconstruct the phenomenon and infer its causes. The site is very complex to be studied especially due to logistic problems, therefore, measurements and observations that are common practice in other landslides are very difficult to apply here. So, many of the results achieved are not adequately supported by field studies. Anyway, the following factors could have affected the stability of the slope: i) the tectonic structure of the area, which is reflected on the morphology and on the geomechanics characteristics of the rock masses; ii) the meteorological conditions during 3 months before the main failure, resulting in an extremely high temperature compared to historical data. Moreover, the analysis of multitemporal satellite images allowed to recognize that it was not a single landslide but that the phenomenon is articulated over time in at least five failures in about 2 months. Moreover, several predisposing factors may have been playing an important role in causing the instability: the degradation of permafrost (probably affecting rock mass due to the circulation of warm air and water in the discontinuity systems), the alternance of the freeze-thaw cycles and the availability of a considerable amount of water from rainfalls and nival fusion infiltrating deeply in the rock mass. More common causes such as rains and earthquakes have been excluded
Convenzione per un’attività di Ricerca finalizzata allo sviluppo e al test del brevetto relativo al metodo per aumentare la capacità portante dei terreni e per sollevare edifici mediante precarica meccanica di interte onttenuta per compressione di martinetto idraulico in assenza di vibrazioni. Responsabile della Ricerca: Prof. Cesare Comina; Co-Responsabile della Ricerca: Prof. Giuseppe Mandrone: Collaboratori: Jessica Maria Chicco, PhD; Dr. Damiano Vacha
No full textConvenzione per un’attività di Ricerca per la realizzazione di un innovativo impianto geotermico a bassa entalpia, finalizzato alla riduzione dei consumi energetici per la gestione di un magazzino frigorifero mediante l’utilizzo di fonti rinnovabili (Vigasio, Verona) Responsabile Scientifico: Prof. Giuseppe Mandrone Collaboratore: Dr. Jessica Maria Chicco, PhD
No full textHybrid (Gas and Geothermal) Greenhouse Simulations Aimed at Optimizing Investment and Operative Costs: A Case Study in NW Italy
Full text linkGenerally, greenhouses are high energy-consuming, sometimes accounting for 50% of the cost of greenhouse production. Geothermal energy plays a very important role in maintaining the desired temperature and reducing energy consumption. This work deals with a project of a hybrid heating plant (97% geothermal energy and 3% gas-condensing boiler) for the innovative Plant Phenotyping Greenhouse at the University Campus in Grugliasco (few km West of the city of Turin). The aim of the study is to testify to the energy efficiency of this kind of hybrid plant as well as its economic sustainability. Numerical simulations of a GRT were used to calibrate the system and verify that the software reasonably modeled the real case. They helped to correctly size the geothermal plant, also providing data about the thermal energy storage and production during on and off plant cycles. The results show a thermal power of 50.92 kW over 120 days of plant operation, in line with the expected energy needs to meet the base load demand. Long-term results further ensure a negligeable impact on the ground, with a thermal plume between 5 and 10 m from the plant, reducing substantially in a few months after switching off the plant
Le frane connesse agli incendi boschivi: stato dell’arte e sviluppi futuri della ricerca anche alla luce dei cambiamenti climatici
No full textEvery year wildfire causes significant damage worldwide, leading to a severe modification in natural ecosystems and
to economic losses. Moreover, wildfires can have profound effects on the hydrologic response of watersheds by changing
the infiltration rates and erodibility of the soil: this is due to litter removal, ash deposition, soil physical alteration and generation or destruction of water repellent soils. Erosion rates in burned areas can increase more than 800 times
with respect to the unburned situation; an increased susceptibility to debris flow, which may persist for several years
after fire, it’s also affirmed. This work, on the one hand wants to signal that several Italian researchers have started a systematic study on these effects, on the other it wants to show the first results obtained in a case study in
Piedmont. This region is affected by an increasing number of fires, as shown by statistics from the past 50 years.
The case study concerns the area of Bussoleno, in the middle of the Susa Valley (Western Alps) and refers to
phenomena that occurred in the spring / summer 2018 and related to the 2017 fires, when more than 4000 hectares
burned on the slopes of the Rocciamelone, the mountain symbol of the Susa Valley. Several debris flows, triggered
by the first heavy rains, hit the village, causing damage to houses and infrastructures and causing the evacuation
of more than 200 people
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
Preliminary analyses of an innovative soil improving system by sand/gravel injections–Geotechnical and geophysical characterization of a first test site
No full textSeveral soil improving systems are available to increase the geotechnical properties of low resistance soils and increase the stability of overlaying constructions. Most of the already available methods make use of injections of more compacted material inside the ground, like: micro-piles, sand compaction piles, stone columns or grouting. Most of these solutions requires vibrations and rotary drilling, which could compromise soil properties and overlaying building integrity. Recently an innovative soil improving system by injections of a sand/gravel mixture was developed by Novatek® through mechanical preload of the mixture by compression adopting a hydraulic jack. The advantage of this last system with respect to available methods is the absence of vibrations and rotary drilling operations. In this study, the application of this system is documented in a first trial test site in the central Po plain (Italy). Description of the system and of the executed injections are reported. Characteristics of the ground before and after injections are compared, using both geotechnical and geophysical tests, in order to evaluate the system performances, which were also ascertained with direct verification through an explorative trench. The first results reported, even if for limited application depths, highlight the good potentialities of the improving system with respect to the increase of geotechnical parameters in the treated soil
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