Static load tests of driven concrete piles under CFRP confinement     

Jialin Zhou  Xin Zhang  Lin Zhang  Fang Dong  Erwin Oh 《Geomechanics and Geoengineering》2020,15(3):159-171

ABSTRACT

This paper describes compressive static load tests of concrete driven piles confined by Carbon Fibre Reinforced Polymer (CFRP). The tested piles include one concrete pipe pile and one concrete rectangular pile which are all partially confined by CFRP, and other two piles with the same dimensions without CFRP application. Tests program was performed to obtain the behaviours of these composite piles. Four Static Loading Tests (SLTs) were conducted and the results shown that those two types of composite pile demonstrate less vertical displacement with the same loading of traditional concrete piles. Furthermore, the traditional methods of Load-settlement (Q-s) curves, Settlement-lg (Load) (s-lgQ) curves and Settlement-lg (Time) curves are analysed. Due to un-plunging condition, the interpretation methods of Davisson’s, DeBeers, Double-Tangent as well as Chin’s methods are demonstrated for the ultimate bearing capacity of these four piles. It is concluded that the CFRP confinement increased the ultimate bearing capacity and this composite material can be perfectly applied in geotechnical condition.  相似文献   

Fidelity and time resolution of the magnetostratigraphic record in Siwalik sediments: high-resolution study of a complete polarity transition and evidence for cryptochrons in a Miocene fluviatile section     

Wolfgang Rösler  & Erwin Appel 《Geophysical Journal International》1998,135(3):861-875

The Surai Khola section in southwest Nepal, a 5000 m continuously exposed record of fluvial sedimentation since Middle Miocene, was revisited for high-resolution magnetostratigraphy in sequences with expected cryptochrons and reversals of the geomagnetic field. Polarity intervals with durations of a few tens of thousands of years are recorded as zones of stable palaeomagnetic directions. Polarity transitions are recorded as zones with complex demagnetization behaviour of specimens in the sedimentary column. Almost antiparallel palaeoremanence directions, residing in different haematite phases in the same specimens, could generally not be separated properly by thermal demagnetization. Differing demagnetization paths for neighbouring specimens during a reversal suggest that measured transitional directions are not true geomagnetic field directions, but rather are generated by the superposition of variable amounts of at least two almost antiparallel components of magnetization. Accompanying studies of recent river sand deposits demonstrate that these sediments acquire a true depositional remanent magnetization (DRM) with considerable inclination errors and scattered directions for individual specimens.  相似文献   

The Multiple Sources and Patterns of Methane inNorth Sea Waters     

Gregor Rehder  Robin S. Keir  Erwin Suess  Thomas Pohlmann 《Aquatic Geochemistry》1998,4(3-4):403-427

The methane concentration in the atmosphere andsurface water was surveyed along 58° N acrossthe North Sea. In addition, the vertical methanedistribution in the water column was determined at sixstations along the transect. The methane contents ofthe surface water as well as in the water column wereextremely inhomogeneous. Input by freshwater fromriver discharge and injection of methane from thesediment were both observed. The survey continued fromthe western side of the North Sea to the Elbe Riverestuary. The Elbe River appears to have low methaneconcentrations compared to other European rivers, itsaverage input into the North Sea is estimated to be70 nmol s-1 of methane. Near 58° N,1°40' E, an abandoned drill site releases about 25 % ofthe North Sea's emission of methane to the atmosphere.The advective methane transport induced by watercirculation was assessed for May 16, 1994, using a 3-DNorth Sea circulation model. For the period of thissurvey, the North Sea's source strength foratmospheric methane is estimated using in situwind velocities. In comparison to the advectivetransport by the water circulation, the gas flux tothe atmosphere appears to be the dominant sink ofNorth Sea methane. This flux is estimated to bebetween 1500 · 106 mol a-1 and 3100 ·106mol a-1, depending on the relationbetween wind speed and gas transfer velocity.  相似文献   

Organochlorine residues,eggshell thickness,and nest success in barn owls from the Chesapeake Bay     

Erwin E. Klaas  Stanley N. Wiemeyer  Harry M. Ohlendorf  Douglas M. Swineford 《Estuaries and Coasts》1978,1(1):46-53

Eggs of barn owls (Tyto alba) were collected from 18 nests in offshore duck blinds on the Maryland side of the lower Potomac River estuary in 1972 and 1973 and analyzed for organochlorine residues. DDE was found in 100% of the clutches, PCBs in 89%, and dieldrin in 78%. Eggshell thickness was inversely correlated with concentrations of DDE, DDD, and dieldrin residues. Six of the 18 clutches had mean DDE residues above 5 ppm, and eggshell thickness in these six clutches was significantly less (P<0.001) than in the other 12 clutches. The owls produced 1.7 young per active nest in 1973. This rate is slightly below the reproductive rate needed to maintain a stable population. An estimated 15% of the population carried concentrations of organochlorine residues that may have been detrimental to their reproduction. Passerine birds, taken extensively as food by a small proportion of the population, are believed to have been the source of elevated concentrations of organochlorines in these barn owls.  相似文献   

Accuracy of mean gravity anomalies obtained from point and profile measurements     

H. Moritz 《Journal of Geodesy》1966,40(2):157-169

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Interaction of organic compounds with calcium carbonate—III. Amino acid composition of sorbed layers     

Peter J. Müller  Erwin Suess 《Geochimica et cosmochimica acta》1977,41(7):941-949

Nitrogenous organic compounds in sorbed surface layers and in calcified organic matter associated with calcium carbonate sediment particles consist of 40–50% amino acids, 2% amino sugars and 25% ammonia. In grain size classes > 20 μm these compounds are mainly contained in the calcified protein of carbonate secreting organisms but with smaller grain sizes—and consequently increased specific surface area—they are contained in sorbed layers at the mineral surface. The composition of the sorbed layer is characterized by a predominance of neutral amino acids, a relative enrichment of basic and weakly polar amino acids, and a deficiency of acidic amino acids in comparison with the proteinaceous matter of calcifying organisms. The respective abundances for sorbed and calcified matter are: 505 and 380 Res./ of neutral amino acids, 262 and 450 Res./1000 of acidic amino acids, 92 and 51 Res./l000 of basic amino acids, and 141 and 129 Res./1000 of weakly polar amino acids.The composition of the sorbed layer appears to be the result of sorption of proteinaceous matter from solution since it reflects the free and peptide-bound amino acid composition of seawater. The characteristic amino acid assemblage could also be the result of preferential decomposition of protein and subsequent enrichment of neutral and basic amino acids; however, sorption from solution appears more likely since the total amount of amino acids sorbed to calcium carbonate (0.58 mg m ^?2) corresponds closely to the amount of protein known to cover one m² of aqueous substrate in monolayer arrangement. Sorption from solution is further supported by the low arginine/ornithine ratios in both the sorbed layer and the natural dissolved organic matter. This process might lead to a characteristic amino acid spectrum in fine grained calcareous sediments that reflects the composition of the dissolved organic matter in seawater rather than that of the carbonate secreting proteinaceous matter.  相似文献   

Process identification at a slow‐moving landslide in the Vorarlberg Alps     

Falk Lindenmaier  Erwin Zehe  Angela Dittfurth  Jürgen Ihringer 《水文研究》2005,19(8):1635-1651

A fine‐grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the Vorarlberg Alps, Austria. For that purpose intensive hydrometeorological, hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998–2001. Subsurface water dynamics at the creeping slope turned out to be dominated by a three‐dimensional pressure system. The pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south‐western part of the hillslope. The related pressure signal was shown to propagate further downhill, causing fast reactions of the piezometric head at 5·5 m depth on a daily time scale. The observed pressure reactions might belong to a temporary hillslope water body that extends further downhill. The related buoyancy forces could be one of the driving forces for the mass movement. A physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production. It was possible to reproduce surface runoff and observed pressure reactions in principle. However, as soil hydraulic functions were only estimated on pedotransfer functions, a quantitative comparison between observed and simulated subsurface dynamics is not feasible. Nevertheless, the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Stable Cu and Zn isotope ratios as tracers of sources and transport of Cu and Zn in contaminated soil   总被引：7，自引：0，他引：7  

Moritz Bigalke  Stefan Weyer  Jozef Kobza 《Geochimica et cosmochimica acta》2010,74(23):6801-6813

Copper and Zn metals are produced in large quantities for different applications. During Cu production, large amounts of Cu and Zn can be released to the environment. Therefore, the surroundings of Cu smelters are frequently metal-polluted. We determined Cu and Zn concentrations and Cu and Zn stable isotope ratios (δ⁶⁵Cu, δ⁶⁶Zn) in three soils at distances of 1.1, 3.8, and 5.3 km from a Slovak Cu smelter and in smelter wastes (slag, sludge, ash) to trace sources and transport of Cu and Zn in soils. Stable isotope ratios were measured by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) in total digests. Soils were heavily contaminated with concentrations up to 8087 μg g⁻¹ Cu and 2084 μg g⁻¹ Zn in the organic horizons. The δ⁶⁵Cu values varied little (−0.12‰ to 0.36‰) in soils and most wastes and therefore no source identification was possible. In soils, Cu became isotopically lighter with increasing depth down to 0.4 m, likely because of equilibrium reactions between dissolved and adsorbed Cu species during transport of smelter-derived Cu through the soil. The δ⁶⁶Zn_IRMM values were isotopically lighter in ash (−0.41‰) and organic horizons (−0.85‰ to −0.47‰) than in bedrock (−0.28‰) and slag (0.18‰) likely mainly because of kinetic fractionation during evaporation and thus allowed for separation of smelter-Zn from native Zn in soil. In particular in the organic horizons large variations in δ⁶⁶Zn values occur, probably caused by biogeochemical fractionation in the soil-plant system. In the mineral horizons, Zn isotopes showed only minor shifts to heavier δ⁶⁶Zn values with depth mainly because of the mixing of smelter-derived Zn and native Zn in the soils. In contrast to Cu, Zn isotope fractionation between dissolved and adsorbed species was probably only a minor driver in producing the observed variations in δ⁶⁶Zn values. Our results demonstrate that metal stable isotope ratios may serve as tracer of sources, vertical dislocation, and biogeochemical behavior in contaminated soil.  相似文献   

Palynological evidence for Pennsylvanian (Late Carboniferous) vegetation change in the Sydney Coalfield,eastern Canada     

Tatyana K. Dimitrova  Erwin L. Zodrow  Christopher J. Cleal  Barry A. Thomas 《Geological Journal》2010,45(4):388-396

The palynology of clastic samples from seven stratigraphical levels in the late Moscovian Sydney Mines Formation, exposed along the shore at Bras d'Or, Nova Scotia, has been investigated. Most of the samples were from roof shales of major coals; the one sample that was not yielded a much higher proportion of pollen derived from extra‐basinal vegetation. The four stratigraphically lower roof shale samples yielded essentially similar palynological spectra, with 39 ± 4% lycophytes, 9 ± 4% sphenophylls, 23 ± 4% tree‐ferns, 12 ± 4% other ferns and 5 ± 3% cordaites. The palynology of the upper part of the investigated succession suggests a shift in vegetation towards one favouring more marattialean tree‐ferns, cordaites and conifers, and fewer lycophytes. This correlates with changes in drainage patterns as the alluvial plain migrated seawards and thus changed water tables. No evidence was found to suggest significant climate change at this time. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Architecture of Upper Cretaceous rhyodacitic hyaloclastite at the polymetallic Madneuli deposit,Lesser Caucasus,Georgia     

Nino Popkhadze  Robert Moritz  Vladimer Gugushvili 《Central European Journal of Geosciences》2014,6(3):308-329

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