Modeling Gaseous CO2 Flow Behavior in Layered Basalts: Dimensional Analysis and Aquifer Response     

Andrea D'Aniello  Sigrún Tómasdóttir  Bergur Sigfússon  Massimiliano Fabbricino 《Ground water》2021,59(5):677-693

Particular attention is paid to the risk of carbon dioxide (CO₂) leakage in geologic carbon sequestration (GCS) operations, as it might lead to the failure of sequestration efforts and to the contamination of underground sources of drinking water. As carbon dioxide would eventually reach shallower formations under its gaseous state, understanding its multiphase flow behavior is essential. To this aim, a hypothetical gaseous leak of carbon dioxide resulting from a well integrity failure of the GCS system in operation at Hellisheiði (CarbFix2) is here modeled. Simulations show that migration of gaseous carbon dioxide is largely affected by formation stratigraphy, intrinsic permeability, and retention properties, whereas the initial groundwater hydraulic gradient (0.0284) has practically no effect. In two different scenarios, about 18.3 and 30.6% of the CO₂ that would have been injected by the GCS system for 3 days could be potentially released again into the atmosphere due to a sustained leakage of the same duration. As the gaseous leak occurs, the aquifer experiences high pressure buildups, and the presence of a less conductive layer further magnifies these. Strikingly, the dimensional analysis showed that buoyant and viscous forces can be comparable over time within the predicted gaseous plumes, even far from the leakage source. Local pressure gradients, buoyant, viscous, and capillary forces all play an important role during leakage. Therefore, neglecting one or more of these contributions might lead to a partial prediction of gaseous CO₂ flow behavior in the subsurface, giving space to incorrect interpretations and wrong operational choices.  相似文献   

The flow dynamics of an extremely large volume pyroclastic flow,the 2.08-Ma Cerro Galán Ignimbrite,NW Argentina,and comparison with other flow types     

Ray A. F. Cas  Heather M. N. Wright  Christopher B. Folkes  Chiara Lesti  Massimiliano Porreca  Guido Giordano  Jose G. Viramonte 《Bulletin of Volcanology》2011,73(10):1583-1609

The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km³ dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35–60%), pumice (<10% generally) and lithic-poor (<5% generally) rhyodacitic ignimbrite, lacking a preceding plinian fallout deposit. The CGI is preserved up to 80 km from the structural margins of the caldera, but almost certainly was deposited up to 100 km from the caldera in some places. Only one emplacement unit is preserved in proximal to medial settings and in most distal settings, suggesting constant flow conditions, but where the pyroclastic flow moved into a palaeotopography of substantial valleys and ridges, it interacted with valley walls, resulting in flow instabilities that generated multiple depositional units, often separated by pyroclastic surge deposits. The CGI preserves a widespread sub-horizontal fabric, defined by aligned elongate pumice and lithic clasts, and minerals (e.g. biotite). A sub-horizontal anisotropy of magnetic susceptibility fabric is defined by minute magnetic minerals in all localities where it has been analysed. The CGI is poor in both vent-derived (‘accessory’) lithics and locally derived lithics from the ground surface (‘accidental’) lithics. Locally derived lithics are small (<20 cm) and were not transported far from source points. All data suggest that the pyroclastic flow system producing the CGI was characterised throughout by high sedimentation rates, resulting from high particle concentration and suppressed turbulence at the depositional boundary layer, despite being a low aspect ratio ignimbrite. Based on these features, we question whether high velocity and momentum are necessary to account for extensive flow mobility. It is proposed that the CGI was deposited by a pyroclastic flow system that developed a substantial, high particle concentration granular under-flow, which flowed with suppressed turbulence. High particle concentration and fine-ash content hindered gas loss and maintained flow mobility. In order to explain the contemporaneous maintenance of high particle concentration, high sedimentation rate at the depositional boundary layer and a high level of mobility, it is also proposed that the flow(s) was continuously supplied at a high mass feeding rate. It is also proposed that internal gas pressure within the flow, directed downwards onto the substrate over which the flow was passing, reduced the friction between the flow and the substrate and also enhanced its mobility. The pervasive sub-horizontal fabric of aligned pumice, lithic and even biotite crystals indicates a consistent horizontal shear force existed during transport and deposition in the basal granular flow, consistent with the existence of a laminar, shearing, granular flow regime during the final stages of transport and deposition.  相似文献   

The DEM or Mt. Etna: geomorphological and structural implications     

Massimiliano Favalli  Fabrizio Innocenti  Maria Teresa Pareschi  Giorgio Pasquarè  Stefano Branca 《Geodinamica Acta》2013,26(5):279-290

Abstract

A Digital Elevation Model (DEM) of Mt. Etna is presented; it has altimetric and planimetric resolution of 1 m and 5 m, respectively, and covers an area of about 120 km . This 3-D view of Mt. Etna allowed both recognition and location of the main morphostructural and volcano-tectonic features of the volcano. A slope map has been generated from the DEM; on the basis of slope distributions and surface textures, five acclivity domains have been recognized. The largest domain, south of the summit craters, reflects the occurrence of old plateau lavas, distinct from central volcanoes which built the present Etnean volcanic system. Interaction between the central volcanoes, with their summit calderas and failed slopes, produced the other recognised domains. Furthermore, newly identified relevant morphostructural lines are discussed. © Elsevier, Paris  相似文献   

Event Scenario Analysis for the Design of Rockslide Countermeasures   总被引：2，自引：0，他引：2  

GIGLI Giovanni  INTRIERI Emanuele  LOMBARDI Luca  NOCENTINI Massimiliano  FRODELLA William  BALDUCCI Marco  VENANTI Luca Domenico  CASAGLI Nicola 《山地科学学报》2014,(6):1521-1530

The Torgiovannetto quarry（Assisi municipality,central Italy） is an example of a site where the natural equilibrium was altered by human activity,causing current slope instability phenomena which threaten two roadways important for the local transportation.The quarry front,having a height of about 140 m,is affected by a 182,000 m3 rockslide developed in intensely fractured limestone and is too large to be stabilized.In 2003 some tension cracks were detected in the vegetated area above the quarry upper sector.From then on,several monitoring campaigns were carried out by means of different instrumentations（topographic total station,extensometers,inclinometers,ground-based interferometric radar,laser scanner and infrared thermal camera）,allowing researchers to accurately define the landslide area and volume.The latter’s major displacements are localized in the eastern sector.The deformational field appears to be related to the seasonal rainfall.The landslide hazard associated with the worst case scenario was evaluated in terms of magnitude,intensity and triggering mechanism.For the definition of the possible runout process the DAN 3D code was employed.The simulation results were used in order to design and construct a retaining embankment.Furthermore,in order to preserve both the safety of the personnelinvolved in its realization and of the roadways users,an early warning system was implemented.The early warning system is based on daily-averaged displacement velocity thresholds.The alarm level is reached if the prediction based on the methods of Saito（1969） and Fukuzono（1985） forecasts an imminent rupture.  相似文献   

Dust emission in northern China: atmospheric emission–dispersion modelling of a major dust event     

Massimiliano Pasqui  Andrea Taramelli  Jonathan Barbour  Dalia Kirschbaum  Lorenzo Bottai  Caterina Busillo  Francesca Calastrini  Giovanni Gualtieri  Francesca Guarnieri  Chris Small 《地球表面变化过程与地形》2013,38(12):1354-1368

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An integrated procedure for management of bridge networks in seismic areas   总被引：1，自引：1，他引：0  

Federico Carturan  Carlo Pellegrino  Riccardo Rossi  Massimiliano Gastaldi  Claudio Modena 《Bulletin of Earthquake Engineering》2013,11(2):543-559

In this work an integrated procedure for the evaluation of the seismic vulnerability of bridges included in the transportation network and a rational resource allocation for retrofitting with the aim of minimizing the consequences of an earthquake is shown at a network level. Both normal service and post-earthquake emergency conditions are considered as possible scenarios. The final result consists in global delay in the network versus seismic action occurring time. An iterative procedure finally defines the priority for optimal budget allocation for retrofitting. The procedure has been tested on a wide bridge network located in the North-eastern part of Italy.  相似文献   

On the rheological characterisation of liquefied sands through the dam-breaking test     

Gabriele Della Vecchia  Massimiliano Cremonesi  Federico Pisanò 《国际地质力学数值与分析法杂志》2019,43(7):1410-1425

This paper concerns the rheological characterisation of liquefied sands as non-Newtonian Bingham fluids. For this purpose, dam-breaking laboratory tests are often executed and interpreted, offering a viable option to identify the properties of fluidised water-soil mixtures. However, limited attention has been devoted so far to clarify what variables and measurements would allow unambiguous calibration of Bingham parameters, namely, the viscosity η and the yield stress τ_y. The numerical results of parametric studies based on the particle finite element method (PFEM) are critically inspected to gain deeper insight into the problem. First, it is confirmed that multiple η − τ_y pairs may reproduce the same experimental evidence when formed by only one measurement—usually, the post–dam-breaking displacement of the bottom toe (tip) of the liquefied mass. Then, two alternative procedures are proposed for unambiguous identification of both η and τ_y: one is based on monitoring the evolving aspect ratio of the fluid mass during free, gravity-driven flow; the other relies on a slightly different dam-breaking test, also including impact against a rigid obstacle. In particular, the latter approach reduces the relevant duration of the test, reducing the possible influence of reconsolidation effects on the calibration of rheological parameters.  相似文献   

Lava flow hazard and risk at Mt. Cameroon volcano     

Massimiliano Favalli  Simone Tarquini  Paolo Papale  Alessandro Fornaciai  Enzo Boschi 《Bulletin of Volcanology》2012,74(2):423-439

Mt. Cameroon is one of the most active effusive volcanoes in Africa. About 500,000 people living or working around its fertile flanks are subject to significant threat from lava flow inundation. Lava flow hazard and risk were assessed by simulating probable lava flow paths using the DOWNFLOW code. The vent opening probability density function and lava flow length distribution were determined on the basis of available data from past eruptions at Mt. Cameroon volcano. Code calibration was performed through comparison with real lava flow paths. The topographic basis for simulations was the 90-m resolution SRTM DEM. Simulated lava flows from about 80,000 possible vents were used to produce a detailed lava flow hazard map. The lava flow risk in the area was mapped by combining the hazard map with digitized infrastructures (i.e., human settlements and roads). Results show that the risk of lava flow inundation is greatest in the most inhabited coastal areas comprising the town of Limbe, which constitutes the center of Cameroon’s oil industry and an important commercial port. Buea, the second most important town in the area, has a much lower risk although it is significantly closer to the summit of the volcano. Non-negligible risk characterizes many villages and most roads in the area surrounding the volcano. In addition to the conventional risk mapping described above, we also present (1) two reversed risk maps (one for buildings and one for roads), where each point on the volcano is classified according to the total damage expected as a consequence of vent opening at that point; (2) maps of the lava catchments for the two main towns of Limbe and Buea, illustrating the expected damage upon venting at any point in the catchment basin. The hazard and risk maps provided here represent valuable tools for both medium/long-term land-use planning and real-time volcanic risk management and decision making.  相似文献   

Seismic improvement of slender masonry tower by using hysteretic devices and partial prestressing technique     

Lorenzo De Stefani  Roberto Scotta  Massimiliano Lazzari  Anna Saetta 《Bulletin of Earthquake Engineering》2014,12(2):829-853

An innovative system for seismic improvement of slender masonry towers by using hysteretic devices and partial prestressing technique was developed and applied to a case study. The proposed technique consists in a low level of prestressing of the upper part of the tower in order to localize in the un-prestressed lower part of the tower, i.e. a limited zone near the basement, the vertical displacements due to the cracking of masonry under seismic action. The positioning of dissipative devices, such as the Buckling-Restrained Axial Dampers, across the localization zone allows a significant contribution in terms of damping for hysteretic dissipation. The main effect of such an intervention is the reduction of the seismic demand to the tower and consequently the reduction of the top displacement as well as of the level of damage of the masonry. Both numerical analyses and experimental tests on a scale model of a Venetian bell tower were carried out showing the efficiency and reliability of the proposed technique.  相似文献   

Climate change impacts on bedload transport in alpine drainage basins with hydropower exploitation          下载免费PDF全文

Mélanie Raymond Pralong  Jens Martin Turowski  Dieter Rickenmann  Massimiliano Zappa 《地球表面变化过程与地形》2015,40(12):1587-1599

Sediment transport is known to have a significant impact on hydropower infrastructures and changes in sediment transport rates are important for sediment management measures and hydroelectricity production. In this study, we present how climate change may affect bedload transport in 66 high alpine catchments used by hydropower companies in the Valais, Switzerland. Future sediment yield is estimated with a runoff‐based sediment transport model for the two future 30 year time periods 2021–2050 and 2070–2099. The analysis is integrated into a modelling chain in which error‐corrected and downscaled climate scenarios generated in the framework of the ENSEMBLES project are coupled to the hydrological model PREVAH, glacier retreat and bedload transport. To calibrate the sediment transport model, we used the observed sediment volumes in water intakes and reservoirs if such data were available. The results obtained show on average a decrease of sediment yield due to the reduced runoff generation during summer, especially for the scenario period 2070–2099. A shift of the seasonal sediment transport regime with a current maximum during July and August to earlier months in the year is predicted. Projections of future sediment yield rely on the accuracy of the individual modeling chain elements. The different sources of uncertainty are discussed qualitatively. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献