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31.
Antonello De Luca Elena Mele Javier Molina Guido Verzeletti Artur V. Pinto 《地震工程与结构动力学》2001,30(8):1125-1145
An experimental test program on a full‐scale model representing a sub‐assemblage of the cloister facade of the Sao Vicente de Fora monastery, retrofitted through base isolation, has been recently carried out at the European Laboratory for Structural Assessment of the Joint Research Centre of the European Commission. In this paper an overview of the laboratory model and the experimental results is provided. In particular, firstly the test model is described, including the geometry and mechanical properties of the masonry specimen and the design of the isolation devices; then the testing method and the sub‐structuring of the isolation system are described and the seismic inputs adopted for the pseudo‐dynamic tests are defined. Finally, the experimental results are discussed and compared to the analogous results obtained on the ‘as is’, fixed‐base sub‐assemblage model. The implications of the test outcomes are emphasized and developments of this research line are presented. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
32.
Livio Pastori Elio Antonello Massimo Fracassini Laura E. Pasinetti 《Astrophysics and Space Science》1982,86(1):179-184
The results of radial velocity measures of the star o And from high dispersion plates relative to the years 1964, 1966, 1975 and 1976 are given. The averaged values of the 1964 and 1966 plates confirm the existence of the minimum in the trend of the radial velocities and fit well the curve obtained in the hypothesis of periodic long-term radial velocity variations with the period of 23.5 years (Fracassiniet al., 1977). Preliminary orbital elements in the hypothesis of a long period spectroscopic binary system have been tentatively drawn. 相似文献
33.
Active lava tubes have much higher temperatures than the surrounding rocks. Any change in the tube temperature produces a
change in the temperature distribution in the rocks and induces a thermoelastic deformation in them. We calculate such a deformation
by solving the equilibrium equation of linear thermoelasticity. We assume that the initial temperature distribution in the
medium is the steady-state solution of the heat equation for a very long cylindrical tube at constant temperature, embedded
in a medium with uniform thermal conductivity. We calculate the displacement and stress fields in the medium following to
a temperature change of the tube. A temperature increase produces a dilatation of the medium and a contraction of the tube,
while a temperature decrease produces the opposite effect. For a temperature change equal to 100 K, thermal stresses in the
order of 10 MPa are produced, which are large enough to fracture the rocks surrounding the tube. 相似文献
34.
Maria Cristina Follesa Cristina Porcu Alice Gastoni Antonello Mulas rea Sabatini & Angelo Cau 《Marine Ecology》2009,30(S1):188-199
Community structure and faunal composition of bathyal decapod crustaceans off South-Eastern Sardinian deep-waters (Central-Western Mediterranean) were investigated. Samples were collected during 32 hauls between 793 and 1598 m in depth over the 2003–2007 period. A total of 1900 decapod specimens belonging to 23 species were collected. Multivariate analysis revealed the occurrence of three faunistic assemblages related to depth: (i) an upper slope community at depths of 793–1002 m; (ii) a middle slope community at depths of 1007–1212 m and (iii) a lower slope community at depths greater 1420 m. In the upper and middle slopes the benthic ( Polycheles typhlops ) and epibenthic–endobenthic feeders (mainly Aristeus antennatus and Geryon longipes ), which eat infaunal prey, were dominant, followed by the macroplankton–epibenthic feeders such as Acanthephyra eximia and Plesionika acanthonotus . In the deepest stratum, the most remarkable feature was the prevalence of macroplankton–epibenthic feeders ( A. eximia and P. acanthonotus ). A small percentage of the benthic deep-sea lobster Polycheles sculptus was also present. The biomass presented higher values in the middle slope and declined strongly in the lower slope. There was no general pattern of mean individual weight/size versus depth among decapods, and the changes seemed to be species-specific with different trends. 相似文献
35.
Radar interferometry techniques for the study of ground subsidence phenomena: a review of practical issues through cases in Spain 总被引：5，自引：0，他引：5
R. Tomás R. Romero J. Mulas J. J. Marturià J. J. Mallorquí J. M. Lopez-Sanchez G. Herrera F. Gutiérrez P. J. González J. Fernández S. Duque A. Concha-Dimas G. Cocksley C. Castañeda D. Carrasco P. Blanco 《Environmental Earth Sciences》2014,71(1):163-181
Subsidence related to multiple natural and human-induced processes affects an increasing number of areas worldwide. Although this phenomenon may involve surface deformation with 3D displacement components, negative vertical movement, either progressive or episodic, tends to dominate. Over the last decades, differential SAR interferometry (DInSAR) has become a very useful remote sensing tool for accurately measuring the spatial and temporal evolution of surface displacements over broad areas. This work discusses the main advantages and limitations of addressing active subsidence phenomena by means of DInSAR techniques from an end-user point of view. Special attention is paid to the spatial and temporal resolution, the precision of the measurements, and the usefulness of the data. The presented analysis is focused on DInSAR results exploitation of various ground subsidence phenomena (groundwater withdrawal, soil compaction, mining subsidence, evaporite dissolution subsidence, and volcanic deformation) with different displacement patterns in a selection of subsidence areas in Spain. Finally, a cost comparative study is performed for the different techniques applied. 相似文献
36.
On March 28, 2016, the toe zone of the apparently dormant Pergalla earthslide-earthflow (Northern Apennines, Italy) had a paroxysmal reactivation. In the course of 2 days, displacements up to almost 8 m severely damaged several houses and roads. At the bottom of the slope, the emersion of rotational sliding surfaces determined the uplift of almost 3 m of the Nure river streambed that was consequently partially dammed. The paper describes the landslide event on the basis of field surveys and analysis of post-event aerial photos, as well as data from geophysical surveys and pre- to post-failure displacement monitoring. It also discusses the possible concurrent causes of the event, including antecedent rainfall, the migration of active streambed channels of Nure river toward the landslide toe in the previous year, and the existence of long-term pre-failure slow movements. It is concluded that these factors, together with the presence of sliding surfaces extending beneath the valley floor, should be primarily considered if a preventive assessment of river damming potential due to streambed uplift should be made for other similar landslides in the Apennines. 相似文献
37.
Juan Manuel Pardo Antonio Lozano Gerardo Herrera Joaquín Mulas Ángel Rodríguez 《Environmental Earth Sciences》2013,70(5):1957-1963
This paper presents the results of investigations of the generalized subsidence occurring in and around the city of Murcia, Spain. Based on this research, this is the first integrated investigation of its type performed in Spain. The phenomenon of ground consolidation in the city of Murcia leads to the appearance of severe cracking and settlement in buildings. Subsidence is the result of two factors: on the one hand, the nature of the ground in this area, as it is made of recent deposits of clay and soft limes filled in with clay–lime backfills in the top layers. On the other hand, the increase in groundwater withdrawal during the 1992–95 drought led to a decrease in the water level of a magnitude never before recorded in the city. The risk prevention management suggested convenience of the installation of a measurement network to study and follow the phenomena of the subsidence to quantify it and to calibrate this theoretical model. This network is composed of extensometers and piezometers, the best devices to measure moderate ground movements, which is the case of Murcia. The first phase (Phase I) of this study of ground settlement in the metropolitan area of Murcia involved the installation of a network with 22 extensometers and taking the first measurement series. In a second phase (Phase II), during a period of 4 years, measurements with extensometers were performed to make the analysis and calibration of the theoretical model. Experience and data analysis showed the convenience of installation of new control points with an incremental extensometer and a piezometer in close position with the aim of precisely correlating piezometric levels with the observed subsidence. The third phase (Phase III) started in 2007, a new control technique, based on radar interferometry (InSAR), is being employed to provide information about subsidence in areas not previously monitored. 相似文献
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39.
We propose a model which describes the formation of a strong asperity on a fault. We consider a fault surface which differs slightly from a plane due to a jog-like topographic variation. The fault is placed in an elastic space and is subject to a uniform stress field. The orientation of the fault is such that the normal traction (which is compressive) is greater on the topographic variation, determining a higher static friction and hence an asperity. The value of friction on this asperity depends on the magnitude of shear stress. For times of seismological interest, the increase in shear stress, at rates typical of tectonic processes, does not produce a sensible increase in friction with respect to the adjacent fault segments. A considerable increase in friction and the formation of a strong asperity (or even a barrier) can occur due to repeated seismic-slip episodes on the fault. Slip results in an elastic medium deformation, causing an increase in normal traction on the asperity and hence in friction. This process is described with the aid of a tensile Somigliana dislocation. Regions with high friction undergo partial fracturing of the fault-face material, which can produce fault gouge. The tensile dislocation introduces a small non-double-couple component in the seismic moment of the seismic event, the magnitude of this component depending mainly on the relative size of the asperity. 相似文献
40.
This work focuses on the modelling issues related to the adoption of the pushover analysis for the seismic assessment of existing reinforced concrete (RC) structures. To this purpose a prototype reference structure, one of the RC shear walls designed according to the multi‐fuse concept and tested on shaking table for the CAMUS project, is modelled at different levels of refinement. The meso‐scale of a stiffness‐based fibre element and the micro‐scale of the finite element (FE) method are herein adopted; in the latter separate elements are adopted for the concrete, the steel and the steel–concrete interface. This first of the two companion papers presents in detail the wall under study, illustrating the design philosophy, the geometry of the wall, the instrumentation set‐up and the test programme. The two modelling approaches are then described; the most important points in terms of element formulation and constitutive relations for materials are presented and discussed for each approach, in the light of the particular design of the wall and of its experimental behaviour. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献