Antiplane response of a dike with flexible soil-structure interface to incident SH waves   总被引：2，自引：0，他引：2  

Abdul Hayir  Maria I. Todorovska  Mihailo D. Trifunac 《Soil Dynamics and Earthquake Engineering》2001,21(7)

Studies of the effects of differential ground motions on structural response generally do not consider the effects of the soil-structure interaction. On the other end, studies of soil-structure interaction commonly assume that the foundation of the structure (surface or embedded) is rigid. The former ignore the scattering of waves from the foundation and radiation of energy from the structure back to the soil, while the latter ignore quasi-static forces in the foundations and lower part of the structure deforming due to the wave passage. This paper studies a simple model of a dike but considers both the soil-structure interaction and the flexibility of the foundation. The structure is represented by a wedge resting on a half-space and excited by incident plane SH-waves. The structural ‘foundation’ is a flexible surface that can deform during the passage of seismic waves. The wave function expansion method is used to solve for the motions in the half-pace and in the structure. The displacements and stresses in the structure are compared with those for a fixed-base model shaken by the free-field motion. The results show large displacements near the base of the structure due to the differential motion of the base caused by the wave passage.  相似文献   

Influence of artificial groundwater lakes on the abundance and activity of bacteria in adjacent subsurface systems     

Albin Alfreider  Maria Loferer-Krssbacher  Roland Psenner 《Limnologica》2001,31(4):249-255

Bacterial abundances and activity, estimated by 4′,6-diamidino-2-phenylindole staining (DAPI) and the reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT), were investigated in two oligotrophic artificial groundwater lakes and the surrounding aquifers. To evaluate the effect of lake water on groundwater downstream, samples were taken from wells at different distances from the lakes, and the total number of bacteria and the number of active bacteria in these samples were compared with samples collected upstream. In addition, sterilized sandy sediments were exposed in groundwater wells to measure the number and activity of bacteria attached to particles. At one of the study sites, where the lake sediments were disturbed by dredging, total bacterial abundance and the number of respiring bacteria in the groundwater aquifer was clearly influenced by the lake water. The average bacterial abundances decreased from 2.6 ± 1.9 × 10⁵ cells ml⁻¹ in the well closest to the lake (S2) to 2.9 ± 3.8 × 10⁴ cells ml⁻¹ in the most distant one (S4), which was equivalent to cell numbers in the upstream well. The number of respiring bacteria showed a similar tendency with 1.3 ± 2.7 × 10⁴ active cells ml⁻¹ in S2 and 1.9 ± 1.5 × 10³ active cells ml⁻¹ in S4. At the second study site, which was not influenced by dredging, bacteria in the downstream wells seemed not to be affected by the lake water. The number and activity of bacteria, which colonized exposed sediments, were not significantly different in the upstream and downstream wells, indicating a minor influence of lake water on this habitat. Our results suggest that gravel-pit lakes may influence the free living bacterial assemblages in nearshore groundwater systems, but do not visibly affect numbers and activity of bacteria attached to the surface of aquifer sediments.  相似文献   

Effects of UV on carbon assimilation of phytoplankton in a mixed water column   总被引：1，自引：0，他引：1  

Jan Köhler  Mechthild Schmitt  Hartwig Krumbeck  Maria Kapfer  Elena Litchman  Patrick J. Neale 《Aquatic Sciences - Research Across Boundaries》2001,63(3):294-309

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Xixth International Congress of Photogrammetry and Remote Sensing     

Roger P. Kirby  George Joseph  Ian J. Doqman  Yi Dong Huang  Gordan Petrie  Stuart Robson  Tania Maria Sausen  Ian D. Downey  & A. Stewart Walker 《The Photogrammetric Record》2001,17(97):119-155

The XIXth International Congress of Photogrammetry and Remote Sensing was held at the Amsterdam RAI International Exhibition and Congress Centre, the Netherlands, from 16th to 23rd July 2000. Reports are given on the Congress as a whole, including the General Assembly, some Technical Commission activities and the Congress Exhibition. Papers from the Congress are published in the International Archives of Photogrammetry and Remote Sensing, 33.  相似文献   

Water balance of basins in central Greece: Comparison with other circum-Mediterranean basins and validity of empirical methods   总被引：1，自引：0，他引：1  

George Soulios  Maria Toubektsi  George Tzevelekis  Haniel Ezeigbo 《Environmental Geology》1991,18(2):85-94

The geological and physicogeographical elements of the neighboring basins of Xyniada and Sofaditi in central Greece are given. The average annual and monthly amounts of precipitation that each basin receives for a nineyear period (1972–1981) are estimated by analyzing the data of eight rain gauges. The average annual value of total runoff is also obtained by frequent discharge measurements at the basin outlets during the same period of record, and the water balance of the basins is thus estimated. The examined basins are compared to others in the circum-Mediterranean region. Finally, various empirical methods of estimating components of water balance are applied, and opinions are expressed about the correspondence of these methods to reality and the way they are applied.  相似文献   

Book reviews     

Kacper R. Rybicki  Vernon F. Cormier  Manfred Koch  B. Ducarme  Gary Mavko  Maria Jeleńska  Frazer Tabeart  Yu. N. Korenkov 《Pure and Applied Geophysics》1992,138(3):507-527

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A new method of cubature using spline functions     

Dr. Ing. Paul Dierckx  Dr. Ing. Eduard Smets  Prof. Dr. Ing. Robert Piessens  Ing. Maria Temmerman 《Ocean Dynamics》1981,34(2):61-79

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Paleoclimatic record of a long deep sea core from the eastern Mediterranean     

Maria Bianca Cita  Colette Vergnaud-Grazzini  Christian Robert  Hervé Chamley  Neri Ciaranfi  Sara d&#x;Onofrio 《Quaternary Research》1977,8(2):205-235

A deep-sea core over 16 m long from the crestal area of the Mediterranean Ridge has been investigated with different techniques, including quantitative micropaleontology, stable isotopes (measured on the epipelagic species Globigerinoides ruber and on the mesopelagic species Globorotalia inflata), and clay mineralogy. The resulting record of climatic fluctuations can be cross correlated to other Mediterranean cores by means of isochronous lithologies (tephra layers and sapropels). The climatic record of the Mediterranean is similar in character, phase, and chronology to the records investigated in the equatorial Pacific and in the Caribbean. Isotope stages 1 to 17 have been recognized. Cyclically repeated stagnant cycles resulting in sapropel deposition complicate both the isotopic and the faunal signal. The isotopic investigations reveal that the temperature change in the surface layers of the eastern Mediterranean was no greater than 8°C in the late “glacial” Pleistocene. The chronostratigraphic and biostratigraphic interpretation of Core KS09 indicate that the mean sedimentation rate was 2.4 cm/1000 years, a value very close to the 2.5 cm/1000 years calculated for the entire Quaternary section at DSDP Site 125, also located in the crestal area of the Mediterranean Ridge in the Ionian Basin. The base of KS09 is likely to be very close to the Brunhes/Matuyama boundary dated at 0.7 my.  相似文献   

Use of ²³⁴U/²³⁸U disequilibrium in measuring chemical weathering rate of rocks     

Lycia Maria Moreira-Nordemann 《Geochimica et cosmochimica acta》1980,44(1):103-108

The rate of chemical weathering of rocks has been determined by using uranium as a natural isotopic tracer. The concentration of uranium and ²³⁴U/²³⁸U ratio in natural waters, rocks, and soils of the Preto river basin (Bahia State, Brazil) was measured by alpha-ray spectroscopy.The activity ratio U234/U238 measured in the various samples indicates the uranium fraction which is dissolved from rocks during the weathering process. The results obtained show that 1 m of rock needs 25,000 yr to be weathered in this region under present climatic conditions.  相似文献   

Heavy metals in ionian and tyrrhenian waters from a section of the sicilian coast     

Maria Alpha  Corrado Caristi  Guiseppe Cimino  Marisa Ziino 《Marine pollution bulletin》1982,13(11):399-400

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