A multiphase approach to the stability analysis of reinforced earth structures accounting for a soil–strip failure condition     

Thai Son Quang  Hassen GhaziBuhan de Patrick 《Computers and Geotechnics》2009

A multiphase model, developed in the context of elastoplasticity, is applied to the simulation and design of reinforced earth retaining structures. The main feature of this model is to combine the advantage of a homogenization approach, as regards its computational efficiency, with the ability to account for a specific failure condition at the interface between the soil and the reinforcing strips, which may have a decisive influence on the behavior of the structure. A particular emphasis is put on the stability analysis of this kind of reinforced soil structures, formulated within the framework of the yield design theory. Making use of a generalized rigid block failure mechanism, the stability of a reinforced earth retaining wall is investigated by means of the kinematic approach, leading to upper bound estimates for the stability factor of the structure, which are then favorably compared with the results of an elastoplastic analysis. Special attention is paid to assessing in a quantitative way how a specific soil–strip failure condition affects the stability of the reinforced earth structure as a whole.  相似文献   

Verfahren zur Verhinderung von Verockerungserscheinungen an Steigleitungen,Filterbrunnen, Brunnenelementen und anderen wasserführenden Objekten. Teil 3: Einsatzmöglichkeiten und Ergebnisse an Praxisanlagen     

R. Fischer  H. Reissig  J. Bach  U. Sauer  H. Schwarz  K.-O. Gottschalk  S. Petrich 《洁净——土壤、空气、水》1991,19(1):97-102

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A first detailed look at the Greenland lithosphere and upper mantle, using Rayleigh wave tomography   总被引：2，自引：1，他引：2  

Fiona A. Darbyshire  Tine B. Larsen  Klaus Mosegaard  Trine Dahl-Jensen  Ólafur Gudmundsson  Torben Bach  Søren Gregersen  Helle A. Pedersen  Winfried Hanka 《Geophysical Journal International》2004,158(1):267-286

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The effects of aerosols on the response of a two-dimensional zonally-averaged climate model     

H. J. Jung  W. Bach 《Theoretical and Applied Climatology》1987,38(4):222-233

Summary The response of climate processes to changes in aerosols is investigated using a two-dimensional zonally-averaged climate model. To account for the spatial and temporal heterogeneities of aerosol distributions, a strongly scattering maritime aerosol over ocean and a strongly absorbing rural aerosol over land are used in the layer between the surface and the 700 mb level. The effects of aerosols, gases and clouds on the radiative transfer are computed concurrently using a parameterized form of a two-stream approximation. Aerosols induce a reduction of the solar absorption at the surface and an enhancement of atmospheric absorption. The resulting changes in the climate model parameters are not only a function of the radiatively-active atmospheric constituents, but also of the amplifying or dampening effects of feedback processes employed in the model calculations. For the specified aerosol types and the optical thickness distribution given by Potter and Cess, the annual temperature change at the surface is –2.1 °C with ice-albedo feedback. Without ice-albedo feedback the corresponding value is –1.4 °C. In the present study aerosols produce a cooling effect in the atmosphere at all latitudes.

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Zusammenfassung Der Einfluß von unterschiedlichen Aerosolen auf Klimaprozesse wird mit Hilfe eines zweidimensionalen Klimamodells untersucht. Um die zeitliche und räumliche Variabilität von Aerosolverteilungen zu berücksichtigen, wird über dem Meer ein überwiegend streuendes Aerosol und über Land ein überwiegend absorbierendes Aerosol in der Schicht zwischen dem Erdboden und dem 700 mb Niveau betrachtet. Der Einfluß von Aerosolen, Gasen und Wolken auf den Strahlungstransport wird mit Hilfe einer parametrisierten Zweistromapproximation berechnet. Aerosole verursachen eine Reduzierung der solaren Absorption an der Erdoberfläche und eine Verstärkung der atmosphärischen Absorption. Resultierende Änderungen der Klimamodellparameter sind nicht nur eine Funktion der strahlungsaktiven atmosphärischen Bestandteile, sondern auch von verstärkenden oder dämpfenden Rückkopplungsprozessen. Für die hier benutzten speziellen Aerosoltypen und die Verteilung der optischen Dicke nach Potter and Cess ergibt sich eine Änderung in der Jahresmitteltemperatur von –2,1 °C unter Berücksichtigung des Eis-Albedo-Rückkopplungseffekts. Ohne diesen Mechanismus beträgt die entsprechende Temperaturänderung –1,4 °C. In der Atmosphäre ergibt sich ebenfalls eine Temperaturabnahme in allen Breiten.

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With 7 Figures  相似文献   

Using Geomorphological Indicators to Predict Earthquake Magnitude (MOb‒Max): A Case Study from Cao Bang Province and Adjasent Areas (Vietnam)     

Trong  C. D.  Hoang  N.  Bach  M. X.  Luc  N. M.  Dung  L. V.  Trieu  C. D.  Syrbu  N. S.  Hai  D. Th.  Tuan  Th. A.  Toan  N. Q.  Thanh  D. V. 《Geotectonics》2022,56(3):321-338

Geotectonics - This paper presents analysis of geomorphological indices for predicting the maximum observed earthquake (MOb?Max) in research region, conducted in three steps: (i)...  相似文献   

Comparing the Response of Static Loading Tests on Two Model Pile Groups in Soft Clay     

V. H. L. Bach  H. M. Nguyen  A. J. Puppala  C. M. Nguyen  U. D. Patil 《Geotechnical and Geological Engineering》2018,36(1):13-26

Static load test program was performed on a single pile and two 16-pile groups with equal and different pile lengths. The soil profile consists of sand fill to 0.5 m depth placed on a thick deposit of soft, normally consolidated and compressible clay. The closed end steel pipe piles in 60 mm diameter were installed from 1.5 m through 2.1 m depth within soft clay deposit. The center-to-center distance of piles in group is about 3 times of pile diameter. The strain gages were installed at one level above and two through four levels below ground surface. Tests were carried out about 7 days after driving by method of a series of load increments placed every 5-min until plunging failure occurred. The load at plunging failure for the single pile, the equal-length pile group and the different-length pile group were about 3, 40 and 48 kN, respectively. The movements at start of failure were about 12, 18, and 17 mm, respectively. The analysis of strain gage measurements indicates that the load distribution on piles in the different-length pile group has become significantly uniform.  相似文献   

The amphipod Orchomenella pinguis – A potential bioindicator for contamination in the Arctic     

Lis Bach  Valery E. Forbes  Ingela Dahllf 《Marine pollution bulletin》2009,58(11):1664-1670

Indigenous organisms can be used as bioindicators for effects of contaminants, but no such bioindicator has been established for Arctic areas. Orchomenella pinguis is a benthic amphipod, ubiquitous in the Arctic and can be found in high numbers. We collected O. pinguis at sites with different contamination levels. Population characteristics (body length distribution, average dry weight and amphipod organic content) were related to sediment contaminant concentrations, in order to identify suitable endpoints for using this species as a bioindicator. We show that O. pinguis was prevalent in both clean and contaminated areas, easy to sample and that its population characteristics could be linked to both contamination and sediment organic content. We suggest that O. pinguis is a suitable bioindicator for the Arctic, but that endpoints such as reproductive effects and phenotypic and genotypic responses are needed together with population characteristics to assess impacts of contamination.  相似文献   

Growth Promotion by a Groundwater Fulvic Acid in a Bacteria/Algae System     

C. E. W. Steinberg  S. Bach 《洁净——土壤、空气、水》1996,24(2):98-100

Axenic and bacteria-containing assays with the coccal green alga, Scenedesmus subspicatus, were compared with respect to the growth inhibition and promotion, respectively, of one fulvic acid source. In the presence of Fuhrberg fulvic acids, a groundwater fulvic acid from lignite leachate, algal growth was promoted, if bacteria were present. This effect occurred although fulvic acids clearly quenched the available light. We presume that the fulvic acids were utilized by microbes, which, in turn, may have produced and released organic substances, which appeared to be beneficial to the algae.  相似文献   

地震短临预报困境的思考     

王付良  李彦堂  姬志勇  韩强  张磊 《华北地震科学》2007,25(3):34-36

我国地震工作者长期的探索与努力,证明了地震短临预报是有可能做到的.但地震的复杂性决定了前兆信息的复杂性,使得我们的地震短临预报面临着一些困境,我们对此进行了一些思考.  相似文献   

Simultaneous Organic Matter and Nitrogen Removal from Piggery Slaughterhouse Wastewater Using Bioaugmented Gaslift Membrane Bioreactor     

Nguyen Duc Toan  Nguyen Van Tuyen  Pham Bang Hai  Nguyen Thi Hoang Ha  Do Tien Anh  Bach Quang Dung 《洁净——土壤、空气、水》2023,51(1):2200106

A single bioaugmentation reactor and a side-stream gaslift membrane bioreactor combined with bioaugmentation are conducted to treat real wastewater from a centralized piggery slaughterhouse in Vietnam. The bioaugmented reactor is inoculated with heterotrophic microorganisms (Bacillus sp.) isolated from piggery slaughterhouse wastewater. The results of a single bioaugmentation experiment show high removal efficiency of chemical oxygen demand (COD) (84.8%–97.5%) and total nitrogen (TN) (69.9%–87.2%) at loading rates of 1.28–3.89 and 0.14–0.37 kg m⁻³ d⁻¹, respectively. The combined system demonstrates a significantly higher TN removal efficiency (89.0%–96.1%) (p < 0.001), more stable flux (36.0–38.4 L m⁻² h⁻¹), and transmembrane pressure (0.95–1.05 bar), and better capacity of separation of solid–liquid phases compared to the single bioaugmentation. High COD and TN removal efficiency is possibly due to assimilation and simultaneous nitrification and denitrification processes. The results of this study also indicate the feasibility and propitious efficiency of the bioaugmented gaslift membrane bioreactor for piggery slaughterhouse wastewater treatment.  相似文献