On the uniformity of anthropogenic Venice uplift     

Giuseppe Gambolati  Pietro Teatini  Massimiliano Ferronato  Tazio Strozzi  Luigi Tosi  Mario Putti 《地学学报》2009,21(6):467-473

A programme of Venice uplift because of seawater injection into a 600–800 m deep brackish aquifer underlying the lagoon has recently been advanced. As the actual spatial variability of the hydro‐geological parameters is to a large extent unknown, a controversial issue concerns the 25–30 cm heave prediction with the possible generation of differential displacements that might jeopardize the integrity of the architectural patrimony. It is shown that significant differential displacements have occurred in Venice in the past and are still presently occurring as evidenced by SAR interferometry. The results of a stochastic analysis addressing the variability of the hydraulic conductivity of the injected formation indicate that even a highly uneven aquifer expansion does not migrate to ground surface because of the smoothing effect exerted by the overburden. The predicted differential displacements are well below the values Venice is experiencing. Any a priori alarmism appears to be unfounded and unjustified.  相似文献   

The Late Pleistocene clastic deposits in the Romito Cave,southern Italy: a proxy record of environmental changes and human presence     

Massimiliano Ghinassi  Andrè C. Colonese  Zelia Di Giuseppe  Lisa Govoni  Domenico Lo Vetro  Giulia Malavasi  Fabio Martini  Silvia Ricciardi  Benedetto Sala 《第四纪科学杂志》2009,24(4):383-398

Clastic sediments deposited in caves and rock shelters bear peculiar sedimentological characteristics and have seldom been considered as a high‐resolution proxy record of climatic or environmental changes. The Romito Cave has its entrance at 275 m above sea level, about 25 km from the Tyrrhenian coast of Calabria, southern Italy. New archaeological excavation performed since 2000 has revealed a sedimentary succession spanning the record of Gravettian to Late Epigravettian cultures (Late Pleistocene). The present study focuses on the lower part (2.5 m thick) of the succession, where three main unconformity‐bounded stratigraphic units have been recognised (labelled RM1–3). Each unit consists of water‐lain deposits indicating high‐ to low‐competence flow, capped with anthropogenic deposits. The gradual deactivation and reactivation of the water drainage between 23 475 ± 190 and 16 250 ± 500 cal. a BP is correlated with regional precipitation changes due to the onset of dry climatic conditions of the Last Glacial Maximum. However, the deactivation of cave drainage after the deposition of unit RM3, around 15 400 ± 500 cal. a BP, deviates from the regional hydrological trend of progressively increasing water discharges and is attributed to the drainage cut‐off by probable cave wall collapses. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Effects of offshore platforms on soft-bottom macro-benthic assemblages: a case study in a Mediterranean gas field     

Terlizzi A  Bevilacqua S  Scuderi D  Fiorentino D  Guarnieri G  Giangrande A  Licciano M  Felline S  Fraschetti S 《Marine pollution bulletin》2008,56(7):1303-1309

The exploitation of fossil fuels in the Mediterranean Sea will likely lead to an increase in the number of offshore platforms, a recognized threat for marine biodiversity. To date, in this basin, few attempts have been made to assess the impact of offshore gas and oil platforms on the biodiversity of benthic assemblages. Here, we adopted a structured experimental design coupled with high taxonomic resolution to outline putative effects of gas platforms on soft-bottom macrofauna assemblages in the North Ionian Sea. The analysis was based on a total of 20,295 specimens of 405 taxa, almost entirely identified at species level. Multivariate and univariate analyses showed idiosyncratic patterns of assemblage change with increasing distance from the platforms. Potential reasons underlying such inconsistency are analyzed and the view that structured experimental monitoring is a crucial tool to quantify the extent and magnitude of potential threats and to provide sound baseline information on biodiversity patterns is supported.  相似文献   

Water–gas dynamics and coastal land subsidence over Chioggia Mare field, northern Adriatic Sea     

Pietro Teatini  Domenico Baú  Giuseppe Gambolati 《Hydrogeology Journal》2000,8(5):462-479

A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company. One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth of 1000–1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing a rebound of 0.6–0.7 cm. Electronic Publication  相似文献   

A model for the temperature-dependence of tidal dissipation in convective plumes on icy satellites: Implications for Europa and Enceladus     

Giuseppe Mitri  Adam P. Showman 《Icarus》2008,195(2):758-764

To explain the formation of surface features on Europa, Enceladus, and other satellites, many authors have postulated the spatial localization of tidal heating within convective plumes. However, the concept that enhanced tidal heating can occur within a convective plume has not been rigorously tested. Most models of this phenomenon adopt a tidal heating with a temperature-dependence derived for an incompressible, homogeneous (zero-dimensional) Maxwell material, but it is unclear whether this formulation is relevant to the heterogeneous situation of a warm plume surrounded by cold ice. To determine whether concentrated dissipation can occur in convective plumes, we develop a two-dimensional model to compute the volumetric dissipation rate for an idealized, vertically oriented, isolated convective plume obeying a Maxwellian viscoelastic compressible rheology. We apply the model to the Europa and Enceladus ice shells, and we investigate the consequences for partial melting and resurfacing processes on these bodies. We find that the tidal heating is strongly temperature dependent in a convective ice plume and could produce elevated temperatures and local partial melting in the ice shells of Europa and Enceladus. Our calculation provides the first quantitative verification of the hypothesis by Sotin et al. [Sotin, C., Head, J.W., Tobie, G., 2002. Geophys. Res. Lett. 29. 74-1] and others that the tidal dissipation rate is a strong function of temperature inside a convective plume. On Europa, such localized heating could help allow the formation of domes and chaos terrains by convection. On Enceladus, localized tidal heating in a thermal plume could explain the concentrated activity at the south pole and its associated heat transport of 2-7 GW.  相似文献   

Hybrid simulation of a multi‐span RC viaduct with plain bars and sliding bearings          下载免费PDF全文

Giuseppe Abbiati  Oreste S. Bursi  Philippe Caperan  Luigi Di Sarno  Francisco Javier Molina  Fabrizio Paolacci  Pierre Pegon 《地震工程与结构动力学》2015,44(13):2221-2240

This paper deals with the seismic response assessment of an old reinforced concrete viaduct and the effectiveness of friction‐based retrofitting systems. Emphasis was laid on an old bridge, not properly designed to resist seismic action, consisting of 12 portal piers that support a 13‐span bay deck for each independent roadway. On the basis of an OpenSEES finite element frame pier model, calibrated in a previous experimental campaign with cyclic displacement on three 1:4 scale frame piers, a more complex experimental activity using hybrid simulation has been devised. The aim of the simulation was twofold: (i) to increase knowledge of non‐linear behavior of reinforced concrete frame piers with plain steel rebars and detailing dating from the late 1950s; and (ii) to study the effectiveness of sliding bearings for seismic response mitigation. Hence, to explore the performance of the as built bridge layout and also of the viaduct retrofitted with friction‐based devices, at both serviceability and ultimate limit state conditions, hybrid simulation tests were carried out. In particular, two frame piers were experimentally controlled with eight‐actuator channels in the as built case while two frame piers and eight sliding bearings were controlled with 18‐actuator channels in the isolated case. The remaining frame piers were part of numerical substructures and were updated offline to accurately track damage evolution. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Effects of the filtering action exerted by piles on the seismic response of RC frame buildings     

Luca de Sanctis  Raffaele Di Laora  Nicola Caterino  Giuseppe Maddaloni  Stefano Aversa  Alessandro Mandolini  Antonio Occhiuzzi 《Bulletin of Earthquake Engineering》2015,13(11):3259-3275

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The effects of L’aquila earthquake on the St. Gemma church in Goriano Sicoli: part II—fem analysis     

Giuseppe Brando  Emanuela Criber  Gianfranco De Matteis 《Bulletin of Earthquake Engineering》2015,13(12):3733-3748

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Seismic performance evaluation of plasterboard partitions via shake table tests   总被引：1，自引：1，他引：0  

Gennaro Magliulo  Crescenzo Petrone  Vittorio Capozzi  Giuseppe Maddaloni  Pauline Lopez  Gaetano Manfredi 《Bulletin of Earthquake Engineering》2014,12(4):1657-1677

The damage of nonstructural components represents the largest contribution to the economic loss caused by an earthquake. Since nonstructural components are not amenable to traditional structural analysis, full-scale experimental testing is crucial to understand their behaviour under earthquake. For this reason, shaking table tests are performed to investigate the seismic behaviour of plasterboard partitions. A steel test frame is properly designed in order to simulate the seismic effects at a generic building storey. The tests are performed shaking the table simultaneously in both horizontal directions. To investigate a wide range of interstorey drift demand and seismic damage, the shakes are performed scaling the accelerograms at eleven different intensity levels. The tested plasterboard partitions from Siniat exhibit a good seismic behaviour, both in their own plane and out of plane, showing limited damage up to 1.1 % interstorey drift ratio. The correlation between the dynamic characteristics of the test setup and the recorded damage is evidenced. Finally, an interesting comparison between the experimental results and the analytical model is also performed.  相似文献   

Evaluation of building fundamental periods and effects of local geology on ground motion parameters in the Siracusa area,Italy     

Francesco Panzera  Sebastiano D’Amico  Giuseppe Lombardo  Emanuela Longo 《Journal of Seismology》2016,20(3):1001-1019

The Siracusa area, located in the southeastern coast of Sicily (Italy), is mainly characterized by the outcropping of a limestone formation. This lithotype, which is overlain by soft sediments such as sandy clays and detritus, can be considered as the local bedrock. Records of ambient noise, processed through spectral ratio techniques, were used to assess the dynamic properties of a sample survey of both reinforced concrete and masonry buildings. The results show that experimental periods of existing buildings are always lower than those proposed by the European seismic code. This disagreement could be related to the role played by stiff masonry infills, as well as the influence of adjacent buildings, especially in downtown Siracusa. Numerical modeling was also used to study the effect of local geology on the seismic site response of the Siracusa area. Seismic urban scenarios were simulated considering a moderate magnitude earthquake (December 13th, 1990) to assess the shaking level of the different outcropping formations. Spectral acceleration at different periods, peak ground acceleration, and velocity were obtained through a stochastic approach adopting an extended source model code. Seismic ground motion scenario highlighted that amplification mainly occurs in the sedimentary deposits that are widespread to the south of the study area as well as on some spot areas where coarse detritus and sandy clay outcrop. On the other hand, the level of shaking appears moderate in all zones with outcropping limestone and volcanics.  相似文献