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11.
This article presents a numeric comparative study of the inelastic structural response of base isolated buildings. The comparative study includes the following isolation systems: laminated rubber bearings, New Zealand one, pure friction and the frictional pendulum ones. The study is based on obtaining non‐linear response spectra for various design parameters using six earthquake records. Usually the base isolation of a new building seeks to maintain the structure in the linear elastic range. The response of old weak buildings or the response of new ones subjected to extreme earthquakes may not be, necessarily, in the aforementioned ideal elastic range. Consequently, it is important to characterize the response of isolated buildings responding inelastically. A conclusion from this research is that the isolators affect significantly the structural response of weak systems. Rubber isolators seem slightly less sensitive to plastification that may occur in the structure compared to friction isolators. Ductility demands in the structure are affected significantly by friction and neoprene protected systems, in particular sliding ones where larger demands are obtained. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
12.
Luis E. Vallejo 《Engineering Geology》1997,48(3-4):159-160
13.
14.
Induced seismicity around the Tous New Dam (Spain) 总被引:2,自引:0,他引:2
15.
16.
An approach for quantifying geomorphological impacts for EIA of transportation infrastructures: a case study in northern Spain 总被引:2,自引:0,他引:2
Jaime Bonachea Viola Maria Bruschi Juan Remondo Alberto Gonzlez-Díez Luis Salas Jurjen Bertens Antonio Cendrero Csar Otero Cecilia Giusti Andrea Fabbri Jos Ramn Gonzlez-Lastra Jos María Aramburu 《Geomorphology》2005,66(1-4):95
A methodological proposal for the assessment of impacts due to linear infrastructures such as motorways, railways, etc. is presented. The approach proposed includes a series of specific issues to be addressed for each geomorphological feature analysed—both ‘static’ and ‘dynamic’—as well as a series of steps to be followed in the process.Geomorphic characteristics potentially affected were initially identified on the basis of a conceptual activities/impacts model that helps to single out geomorphic impacts related to environmental concerns for the area. The following issues were addressed for each individual impact: nature of potential effects; indicators that can be used to measure impacts; criteria of ‘geomorphologic performance’; procedure for measurement/prediction of changes; translation of geomorphologic impacts into significant terms from the viewpoint of human concerns; possible mitigation and/or compensation measures.The procedure has been applied to a case study corresponding to a new motorway in the Basque Country, northern Spain. Geomorphological impacts considered in this analysis included: (1) consumable resources; (2) sites of geomorphological interest; (3) land units with high potential for use, high productivity or value for conservation; (4) visual landscape; (5) slope instability processes. The procedure has been designed for implementation in a Geographic Information System (GIS) environment. Details are given on the application of the method to each individual impact analysed and results are presented in both numerical and map form.Impacts assessed were initially expressed by means of heterogeneous magnitudes, depending on the geomorphological feature considered. Those geomorphological impacts were then translated into significant terms and homogeneous magnitudes. Integration was carried out on the basis of impact values thus obtained. Final integrated results were also expressed in numerical and map form.The method proposed enables comparison of alternatives as well as ‘prediction’ and assessment of impacts in terms directly related to geomorphic characteristics. It also facilitates the expression of those impacts in terms that allow integration with other types of environmental impacts. 相似文献
17.
The kinematic evolution of the Barinas–Apure Basin and the southern Mérida Andes from Lower Miocene to the Present is numerically modelled using flexural isostatic theory and geophysical and geological data. Two published regional transects are used to build up a reference section, which is then used to constrain important parameters (e.g. shortenings and sedimentary thicknesses) for the flexural modelling. To control the location of the main fault system in the flexural model earthquake information is also used. The estimated flexural elastic thickness of the South American lithosphere beneath the Barinas–Apure Basin and the Mérida Andes Range is 25 km. The value for the final total shortening is 60 km. The flexural isostatic model shows that the Andean uplift has caused the South American lithosphere subsidence and the development of the Barinas–Apure Basin.In addition, gravity modelling was used to understand deep crustal features that could not be predicted by flexural theory. Consequently, the best-fit flexural model is used to build a gravity model across the Mérida Andes and the Barinas–Apure Basin preserving the best-controlled structural features from the flexural modelling (e.g. basin wavelength and depth) and slightly changing the main bodies density values and deep crustal structures. The final gravity model is intended to be representative of the major features affecting the gravity field in the study area. The predicted morphology in the lower crustal level of the final gravity model favours the hypothesis of a present delamination or megathrust of the Maracaibo crust over the South American Shield. This process would use the Conrad discontinuity as a main detachment surface within an incipient NW dipping continental subduction. 相似文献
18.
The sources of carbon, which fuel water column respiration, remain unresolved for most estuaries; our objective was to examine
carbon dynamics in a shallow subtropical estuary. We sampled the Sabine-Neches estuary, Texas, during low (November 1999)
and high (May 2000) freshwater inflow and measured stable carbon isotope ratios of the dissolved inorganic and orgnaic carbon
(δ13C-DIC, δ13C-DOC), as well as quantifying accessory parameters (salinity, nutrients, total suspended solids, and photosynthetic pigments).
Pigment analysis indicated that diatoms were the predominant phytoplankton. Data from the May 2000 sampling event exhibited
conservative mixing, indicating that the system was acting as a conduit between the watershed and the Gulf of Mexico. During
November, mixing was generally nonconservative indicating extensive recycling of allochthonous and autochthonous carbon sources.
Our data imply that both carbon sources had similar isotope, ratios that made it impossible to unambiguously determine the
dominant source supporting respiration. The nonconservative DIC concentration data indicating an autotrophic sink as well
as the strong relationship between δ13C-DOC and chlorophylla, suggest that in situ production was an important component of the DOC pool. We hypothesize that uncharacteristically calm
wind conditions during sampling may have promoted phytoplankton settling, removing autotrophs, from the water column, but
leaving behind a dissolved biogeochemical signature. Interpretation of carbon dynamics may be confounded by spatial and temporal
decoupling of producers and consumers from biogeochemical indicators. 相似文献
19.
Groundwater contamination with arsenic and other trace elements in an area of the pampa,province of Córdoba,Argentina 总被引:1,自引:0,他引:1
Hugo B. Nicolli Jose M. Suriano Miguel A. Gomez Peral Luis H. Ferpozzi Omar A. Baleani 《Environmental Geology》1989,14(1):3-16
A geochemical study of groundwater of the pampa in the province of Córdoba, Argentina, was performed; the area covered approximately 10,000 km2.Physical-chemical parameters, dissolved solids, and seven trace elements were determined in 60 selected water samples. Systematic and accurate measurements of arsenic, flourine, and vanadium were performed for the first time. Three trace element contaminants not reported earlier were found: an important one, selenium, and two others of less known effects, uranium and molybdenum.Eighty-four percent of the water analyzed showed arsenic contents over 0.05 mg/L, maximum contaminant level established by the U.S. Environmental Protection Agency (1982). The frequency distribution of trace elements was analyzed, and its fit to the lognormal distribution was proved by means of the Pearson and Kolmogorov-Smirnov test; the geographic distribution of the seven trace elements was mapped and its correlation with the anion-cation composition of the water was studied.The maximum arsenic, fluorine, vanadium, and uranium contents were found in the western part of the area under study, in waters containing dominant alkali metals in the cation composition. Maximum selenium and antimony contents were found in the eastern part of the area, while molybdenum distribution does not show any relationship with the other two groups. In addition, the geographic distribution of the trace elements seems to be related to the subsurface structure, which has been inferred using interactive digital analysis of Landsat imagery. The movements of the subsoil have disturbed surface and subsurface drainage influencing the water salinity and trace element contents.In order to investigate the origin of the contamination, 54 loess samples were collected in wells at depths ranging from the surface down to the water table. This loess, which has a high proportion of volcanic components, mainly rhyolitic glass, exhibits a chemical composition corresponding to that of a dacite.The loess and the volcanic glass show anomalous contents of all contaminant trace elements, mainly arsenic and selenium. For this reason loess is considered the most important contamination source in the groundwater under study. 相似文献
20.
Pablo?SarricoleaEmail authorView authors OrcID profile Oliver?Meseguer-Ruiz Javier?Martín-Vide Luis?Outeiro 《Theoretical and Applied Climatology》2018,134(1-2):193-204
Atmospheric circulation patterns in southern Chile (42° 30′ S) were studied in order to determine and analyse the most characteristic synoptic types and their recent trends, as well as to gain an understanding of how they are associated with low-frequency variability patterns. According to the Jenkinson and Collison (J&C) classification method, a 16-point grid of sea-level pressure data was employed. The findings reveal that some synoptic types show statistically significant trends with a 95% confidence level, positively for anticyclonic westerly hybrids (AW) and advective types for third and fourth quadrant wind flows (W, NW, and N) and negatively for SW and cyclonic hybrids (CS and CSW). A model has been constructed of the linear regression of some weather types with teleconnections that most affect Chile: the undetermined types (U), AW were associated with El Niño or the warm phase of the Pacific Decadal Oscillation (PDO), whereas the cyclonic northerly and cyclonic northeasterly types (CN and CNE) were associated with La Niña or cool phase of the PDO. The weather types associated with Antarctic Oscillation (AAO) in its positive phase are anticyclonic northerly and northeasterly and northerly advection types, while in its negative phase are cyclonic southwesterly and advection types. 相似文献