1,720,992 research outputs found
Proprietà dinamiche dei terreni del centro storico di sellano attraverso prove di RCT CLTST e DSDSS
No full textNella presente nota sono riportati i risultati di prove di laboratorio dinamiche (colonna risonante) e cicliche (taglio torsionale e taglio semplice) per la misurazione della rigidezza e dello smorzamento dei campioni di terreno prelevati nel centro abitato di Sellano (Pg), colpito dal terremoto Umbro Marchigiano del 1997. I risultati sperimentali sono espressi in termini di modulo di taglio massimo (Gmax), modulo di taglio normalizzato (Gs/Gmax) e di fattore di smorzamento (D)
Geotechnical seismic hazard evaluation at sellano (Umbria, Italy) using the GIS technique
No full textA tool that has been widely-used in civil engineering in recent years is the geographic information system (GIS) [1]. Geographic Information systems (GIS) are powerful tools for organizing, analyzing, and presenting spatial data. The GIS can be used by geotechnical engineers to aid preliminary assessment through to the final geotechnical design. The aim of this work is to provide some indications for the use of the GIS technique in the field of seismic geotechnical engineering, particularly as regards the problems of seismic hazard zonation maps. The study area is the village of Sellano located in the Umbrian Apennines in central Italy, about 45 km east of Perugia and 120 km north-east of Rome The increasing importance attributed to microzonation derives from the spatial variability of ground motion due to particular local conditions. The use of GIS tools can lead to an early identification of potential barriers to project completion during the design process that may help avoid later costly redesign. © 2008 American Institute of Physics
Dynamic response analysis of earth-retaining walls by means of shaking table tests
No full textThe paper describes the results of some experimental activities performed at the Earthquake Engineering Research Center of Bristol University and related to the seismic response analysis of earth-retaining walls. The activities consist of several shaking table tests performed on a earth-retaining wall system involving a scaled concrete wall model and a Leighton Buzzard sand deposit. The obtained results are presented in terms of amplitude of acceleration and displacement of the wall and are discussed focusing the attention on some aspects of the response generally neglected in the traditional performance-based design approaches. Copyright © (2006) by Earthquake Engineering Research Institute All rights reserved
Geotechnical characterization of ash collected during recent eruptions of Mount Etna: from dangerous waste material to environmental friendly resource
No full textAn exponential increase in the activity of Mount Etna (Catania, Italy) has been observed between the massive eruptions that lasted from 1991 to 1993 and the very significant ones, which occurred between 2012 and 2018. Large amounts of ash repeatedly covered the city of Catania, causing environmental problems for road and air traffic, agriculture and human health. Recent thinking has been to consider volcanic ash as a resource rather than a waste material, thus avoiding damage to both the environment and human health. This goal could be achieved using this material in several fields of geotechnical engineering but first static and dynamic laboratory geotechnical tests must be performed. This paper deals with a static and dynamic geotechnical characterization of volcanic ash collected during recent eruptive activity on Mount Etna. Grading and index properties tests, oedometer tests, direct shear tests and dynamic resonant column tests were performed in the Geotechnical Laboratory at the University of Catania. Particle crushing was also analysed following oedometer tests and direct shear tests. The tested materials are essentially of a gravelly-sandy nature and showed very different strains due to the different grain size distribution curves as well as to the aptitude to crushing of these materials. Cohesion is negligible both at peak state and at the critical state, in line with granular soil behaviour. A light curvature of the failure curves can be observed for some peak envelopes. The results of dynamic tests are in quite good agreement with those of well-known sands. Thus, taking into account crushing, it is possible to appropriately reuse these materials in geotechnical engineering avoiding inhalation and ingestio
Seismic displacements of retaining walls: Shaking table test results vs numerical predictions
Full text linkThe seismic performance of retaining walls is usually evaluated through simplified displacement-based approaches which neglect the change in the soilwall system geometry as displacements develop. In this vein, the paper describes the results of several shaking table tests carried out on a reduced-scale model of a retaining wall placed inside a flexible soil container and subjected to harmonic input motions. In the paper the permanent displacements of the wall and of the retained soil were presented and compared with numerical predictions obtained using a modified Newmark-type model, which encompasses the kinematic compatibility between the wall and the soil
Evaluation of the destructive potential of the 1997-1998 earthquake ground motion in the town of Sellano
Full text linkThe 1997-1998 Umbria-Marche earthquake sequence was characterised by a relatively moderate magnitude (ML = 5-6). Despite that, the earthquake caused extensive damage in different towns, such as in the town of Sellano. Different earthquakes have affected Sellano in the past. In particular, after the earthquakes of 1979 and 1984 most of the buildings of the old centre of Sellano were subjected to intensive seismical remedial works. Nevertheless, many of these buildings suffered significant damage during the 1997-1998 earthquake sequence. The acceleration is widely utilised in seismic routine design; nevertheless, the structure damage analysis and ground motion records obtained in the recent earthquakes indicate a need for the evaluation of other parameters than acceleration to describe the complex relationship between the ground motion and structure damage. The aim of this work is to present new microzonation maps of the PGAPGV ratio, Arias Intensity (Ia,) and destructiveness potential factor (Pd) at the soil surface for the town of Sellano. © 2003 WIT Press
Geotechnical earthquake hazards of the Umbria and Marche regions (Italy)
No full textThe seismic sequence which occurred in the 1997-1998 Umbria and Marche Regions (Central Italy), though characterised by quite moderate magnitudes, caused significant damage to buildings and the failure of many slopes. Such an event gave once more evidence of the need to zone all the seismic areas in relation to the seismic site amplification, landslide and liquefaction phenomena. As far as the 1997-1998 earthquake sequence is concerned, an explanation of extensive damage occurring in spite of moderate magnitude seismic events can be detached in terms of geotechnical characteristics of the soil involved. The high vulnerability of many masonry buildings and the cumulative effect due to the long earthquake repetition also play an important role. The aim of this work is the evaluation of site-dependent response spectra in terms of acceleration, velocity and displacement by means of the analysis of about 150 accelerometric records. The site dependent response spectra, are than compared with those provided by the new draft version of EC8 (2000), which considers seven subsoil classes instead of three classes as the older one (EC8 1994)
Geotechnical characterization of Mount Etna ash for its reuse preserving human health
No full textIn the last decades Mount Etna (Sicily, Italy) has partially modified its activity from effusive toeruptive. From the eruption of 1991–1993 to those of 2015 an exponential increasing of its activity has beenobserved. Large amounts of ash have repeatedly covered the city of Catania. This caused problems on the roadand air traffic, agriculture and human health, above all due to the significant toxicity of this material. The storageof Mount Etna ash has become a great problem. The recent trend is not consider the volcanic ash as a waste, butas a resource. Volcanic ash could be particularly used in Geotechnical Engineering, avoiding environmental andhuman health damage. The present paper deals with human health damage and geotechnical characterizationof Mount Etna ash. The results give interesting information for a rational reuse of this ash in GeotechnicalEngineering preserving the human health
HVSR and MASW seismic survey for characterizing the local seismic response: A case study in Catania area (Italy)
Full text linkMany recent researches show that the site seismic response is strongly influenced by stratigraphic and topographic features. Site response can reduce or amplify the earthquake induced ground motion. An integrated approach based on passive (HVSR) and active (MASW) seismic surveys, was carried out at the Garibaldi Hospital, located in Catania downtown, in order to evaluate the seismic site response. Fourteen environmental noise records, located near some previously mechanical drillings, were carried out and processed by using the Horizontal to Vertical Spectral Ratio (HVSR) technique. Successively, two MASW prospections were performed at the northern and the southern sides of the Hospital building, following the information deduced from the stratigraphic characteristics of soil drillings. The data obtained from this coupled analysis, method and the information derived by mechanical drillings previously performed, allowed us to obtain the site transfer function which can be related to the H/V average spectrum. Such integrated approach, based on passive and active seismic prospections, showed to be a reliable and quick method to obtain information for a site seismic characterization. According to Italian code a Vs30 profile was achieved and the soil type category was determined
Site effect evaluation in sellano (Italy) by 1-D and 2-D numerical analyses
No full textThe 1997-1998 Umbria-Marche seismic sequence induced severe damage to the historical centre of Sellano (Perugia, Italy). During the long aftershock sequence two temporary accelerometric stations, about 300m apart, provided several ground motion records. These data allowed us to investigate the amplification of surface motion which can essentially be ascribed to local seismic effects. A site response study of the historical centre of the village was carried out by means of 1-D and 2-D numerical analyses to clarify the role played by the stratigraphic and topographic effects. The applicability of 1-D and 2-D models was examined by comparing the recorded and calculated acceleration response spectra. 1-D response analyses seem to indicate a significant stratigraphic effect on the ground response. Conversely, 2-D response analyses have shown only moderate amplification effects due to surface topography, which somewhat improved the predictions of site response spectra. © 2005 WIT Press
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