Geotechnical characterization and rockfall simulation of a slope: a practical case study from South Tyrol (Italy)     

Joachim Schweigl  Carlo Ferretti  Ludwig Nssing 《Engineering Geology》2003,67(3-4):281-296

Rockfalls occur often along the state road SS241 Val d'Ega in the Val d'Ega Valley (South Tyrol, Italy). In order to protect the road and the traffic, stabilization works are necessary. Detailed geological and geomorphologic mapping along structural and geomechanic sections was carried out, and experimental rockfall trails were examined on the slope above the state road between km 3.550 and 3.830. Rockfall simulation, rock mass classification and an interpretation of field data, especially concerning joints, wrapped up the investigations. They helped find the specific need for stabilization work and its positioning along the slope. The stabilization works were completed on February 2002. Another important aspect concerns ongoing geotechnical investigations and stabilization works urgently realised during autumn 1999.

This paper is a practical approach in solving rockfall problems along public roads. It should be considered as a workbook for university personnel and also for professional geologists.  相似文献   

<Emphasis Type="Italic">Phragmites</Emphasis> and environmental management: A question of values     

David F. Ludwig  Timothy J. Iannuzzi  Anthony N. Esposito 《Estuaries and Coasts》2003,26(2):624-630

For a common, widespread, and familiar plant,Phragmites australis engenders an enormous level of scientific controversy and emotional conflict. In parts of the world,Phragmites is an important component of healthy ecosystems and an integral (if now minor) contributor to human economies. In other places it is an invading, unfriendly, and ugly weed. To some scientists and environmentalists,Phragmites is an indicator of and key factor in landscape degradation and habitat deterioration. To others, it is a valiant remnant of nature, providing a relatively rich ecology where there might otherwise be only barren and eroding ground. Our review of the literature leads us to conclude thatPhragmites is simply a biological entity. It is not inherently good or bad, since its evolution, biology, and ecology do not give it a value. The controversy overPhragmites, its role in the ecosystem, and the need for and intensity of management efforts are all artifacts of human perspectives. Effective, consistent management decisions (for either control or enhancement ofPhragmites) can only be made on the basis of site-specific scientific findings, a consideration of technologies with their needed level-of-effort, and explicit exposition of the human values driving the management options. We present a simple decision model to illustrate the interaction of these management components forPhragmites in the environment.  相似文献   

Li abundances in eclogite minerals: a clue to a crustal or mantle origin?     

Alan B. Woodland  Hans-Michael Seitz  Rainer Altherr  Horst Marschall  Bettina Olker  Thomas Ludwig 《Contributions to Mineralogy and Petrology》2002,144(1):128-130

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Sodic Pyroxene and Sodic Amphibole as Potential Reference Materials for In Situ Lithium Isotope Determinations by SIMS     

Michael A.W. Marks  Roberta L. Rudnick  Thomas Ludwig  Horst Marschall  Thomas Zack  Ralf Halama  William F. McDonough  Detlef Rost  Thomas Wenzel  Edward P. Vicenzi  Ivan P. Savov  Rainer Altherr  Gregor Markl 《Geostandards and Geoanalytical Research》2008,32(3):295-310

Two large pegmatitic crystals of sodic pyroxene (aegirine) and sodic amphibole (arfvedsonite) from the agpaitic igneous Ilímaussaq Complex, south Greenland were found to be suitable as reference materials for in situ Li isotope determinations. Lithium concentrations determined by SIMS and micro‐drilled material analysed by MC‐ICP‐MS generally agreed within analytical uncertainty. The arfvedsonite crystal was homogeneous with [Li] = 639 ± 51 μg g^?1 (2s, n = 69, MC‐ICP‐MS and SIMS results). The aegirine crystal shows strongly developed sector zoning, which is a common feature of aegirines. Using qualitative element mapping techniques (EPMA), the homogeneous core of the crystal was easily distinguished from the outermost sectors of the crystals. The core had a mean [Li] of 47.6 ± 3.6 μg g^?1 (2s, n = 33) as determined by SIMS. The seven micro‐drilled regions measured by solution MC‐ICP‐MS returned slightly lower concentrations (41–46 μg g^?1), but still overlap with the SIMS data within uncertainty. Based on MC‐ICP‐MS and SIMS analyses, the variation in δ⁷Li was about 1‰ in each of the two crystals, which is smaller than that in widely used glass reference materials, making these two samples suitable to serve as reference materials. There was, however, a significant offset between the results of MC‐ICP‐MS and SIMS. The latter deviated from the MC‐ICP‐MS results by ?6.0 ± 1.9‰ (2s) for the amphibole and by ?3.9 ± 1.9‰ (2s) for the aegirine. This indicates the presence of a significant matrix effect in SIMS determinations of Li isotopes for amphibole and pyroxene relative to the basalt glasses used for calibration. Based on the MC‐ICP‐MS results, mean δ⁷Li values of +0.7 ± 1.2‰ (2s, n = 10) for the arfvedsonite crystal and of ?3.7 ± 1.2‰ (2s, n = 7) for the core of the aegirine crystal were calculated. Adopting these values, SIMS users can correct for the specific IMF (instrumental mass fractionation) of the ion probe used. We propose that these two crystals serve as reference materials for in situ Li isotope determinations by SIMS and pieces of these two crystals are available from the first author upon request.  相似文献   

Calcium isotope fractionation in modern scleractinian corals     

Florian Böhm  Nikolaus Gussone  Anton Eisenhauer  Stéphanie Reynaud 《Geochimica et cosmochimica acta》2006,70(17):4452-4462

The ⁴⁴Ca/⁴⁰Ca ratios of cultured (Acropora sp.) and open ocean (Pavona clavus, Porites sp.) tropical reef corals are positively correlated with growth temperature. The slope of the temperature-fractionation relation is similar to inorganic aragonite precipitates. However, δ^44/40Ca of the coral aragonite is offset from inorganic and sclerosponge aragonite by about +0.5‰. This offset can neither be explained by the very fast, biologically controlled calcification of scleractinian corals, nor as a consequence of calcification from a partly closed volume of fluid. As corals actively transport calcium through several cell layers to the site of calcification, the most likely explanation for the offset is a biologically induced fractionation. Our results indicate a limited use of Ca isotopes in scleractinian corals as temperature proxy.  相似文献   

Wirkung einer nächtlichen Abschirmung der elektrischen Feldstärke bei Rheumatikern     

Dr. rer. nat. H. W. Ludwig 《Theoretical and Applied Climatology》1973,21(2-3):305-311

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A deglaciation model of the Oberhasli,Switzerland          下载免费PDF全文

Christian Wirsig  Jerzy Zasadni  Susan Ivy‐Ochs  Marcus Christl  Florian Kober  Christian Schlüchter 《第四纪科学杂志》2016,31(1):46-59

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Towards a cross-domain interoperable framework for natural hazards and disaster risk reduction information     

Robert Tomas  Matthew Harrison  José I. Barredo  Florian Thomas  Miguel Llorente Isidro  Manuela Pfeiffer  Otakar Čerba 《Natural Hazards》2015,78(3):1545-1563

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Stratigraphy and Mesozoic–Cenozoic tectonic history of northern Sierra Los Ajos and adjacent areas,Sonora, Mexico     

William R. Page  Floyd Gray  Alexander Iriondo  Daniel Miggins  Robert B. Blodgett  Florian Maldonado  Robert J. Miller 《Journal of South American Earth Sciences》2010,29(3):557-571

Geologic mapping in the northern Sierra Los Ajos reveals new stratigraphic and structural data relevant to deciphering the Mesozoic–Cenozoic tectonic evolution of the range. The northern Sierra Los Ajos is cored by Proterozoic, Cambrian, Devonian, Mississippian, and Pennsylvanian strata, equivalent respectively to the Pinal Schist, Bolsa Quartzite and Abrigo Limestone, Martin Formation, Escabrosa Limestone, and Horquilla Limestone. The Proterozoic–Paleozoic sequence is mantled by Upper Cretaceous rocks partly equivalent to the Fort Crittenden and Salero Formations in Arizona, and the Cabullona Group in Sonora, Mexico.Absence of the Upper Jurassic–Lower Cretaceous Bisbee Group below the Upper Cretaceous rocks and above the Proterozoic–Paleozoic rocks indicates that the Sierra Los Ajos was part of the Cananea high, a topographic highland during the Late Jurassic and Early Cretaceous. Deposition of Upper Cretaceous rocks directly on Paleozoic and Proterozoic rocks indicates that the Sierra Los Ajos area had subsided as part of the Laramide Cabullona basin during Late Cretaceous time. Basal beds of the Upper Cretaceous sequence are clast-supported conglomerate composed locally of basement (Paleozoic) clasts. The conglomerate represents erosion of Paleozoic basement in the Sierra Los Ajos area coincident with development of the Cabullona basin.The present-day Sierra Los Ajos reaches elevations of greater than 2600 m, and was uplifted during Tertiary basin-and-range extension. Upper Cretaceous rocks are exposed at higher elevations in the northern Sierra Los Ajos and represent an uplifted part of the inverted Cabullona basin. Tertiary uplift of the Sierra Los Ajos was largely accommodated by vertical movement along the north-to-northwest-striking Sierra Los Ajos fault zone flanking the west side of the range. This fault zone structurally controls the configuration of the headwaters of the San Pedro River basin, an important bi-national water resource in the US-Mexico border region.  相似文献   

Probabilistic collocation and lagrangian sampling for advective tracer transport in randomly heterogeneous porous media     

Florian Müller  Patrick JennyDaniel W. Meyer 《Advances in water resources》2011,34(12):1527-1538

The Karhunen-Loeve (KL) decomposition and the polynomial chaos (PC) expansion are elegant and efficient tools for uncertainty propagation in porous media. Over recent years, KL/PC-based frameworks have successfully been applied in several contributions for the flow problem in the subsurface context. It was also shown, however, that the accurate solution of the transport problem with KL/PC techniques is more challenging. We propose a framework that utilizes KL/PC in combination with sparse Smolyak quadrature for the flow problem only. In a subsequent step, a Lagrangian sampling technique is used for transport. The flow field samples are calculated based on a PC expansion derived from the solutions at relatively few quadrature points. To increase the computational efficiency of the PC-based flow field sampling, a new reduction method is applied. For advection dominated transport scenarios, where a Lagrangian approach is applicable, the proposed PC/Monte Carlo method (PCMCM) is very efficient and avoids accuracy problems that arise when applying KL/PC techniques to both flow and transport. The applicability of PCMCM is demonstrated for transport simulations in multivariate Gaussian log-conductivity fields that are unconditional and conditional on conductivity measurements.  相似文献