Evaluation of ground snow loads in the micro-climate regions     

M. C. Aydin  E. Işhik 《Russian Meteorology and Hydrology》2015,40(11):741-748

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Quasi‐static analysis of elastic behavior for some systems having higher fracture densities     

James G. Berryman  Atilla Aydin 《国际地质力学数值与分析法杂志》2010,34(16):1687-1724

Elastic behavior of geomechanical systems with interacting (but not intersecting) fractures is treated using generalizations of the Backus and the Schoenberg–Muir methods for analyzing layered systems whose layers are intrinsically anisotropic due to locally aligned fractures. By permitting the axis of symmetry of the locally anisotropic compliance matrix for individual layers to differ from that of the layering direction, we derive analytical formulas for interacting fractured regions with arbitrary orientations to each other. This procedure provides a systematic tool for studying how contiguous, but not yet intersecting, fractured domains interact, and provides a direct (though approximate) means of predicting when and how such interactions lead to more dramatic weakening effects and ultimately to failure of these complicated systems. The method permits decomposition of the system elastic behavior into specific eigenmodes that can all be analyzed, and provides a better understanding about which of these specific modes are expected to be most important to the evolving failure process. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Distribution of rare earth elements and oxyhydroxide phases within a weathered felsic igneous profile in Hong Kong     

N.S. Duzgoren-Aydin  A. Aydin 《Journal of Asian Earth Sciences》2009,34(1):1-9

Variation in type and abundance of oxyhydroxide phases and the fractionation of rare earth elements (REE) within a weathered felsic pyroclastic profile in Hong Kong were investigated in order to assess the key factors and micro-environmental conditions controlling their distribution during weathering at rock and mineral scales. Three types of oxyhydroxide phases (Fe-, Mn- and Ce-rich) were recognized based on their most abundant elements. The Fe-rich types appeared in all samples at different stages of weathering. The Mn-rich types, however, were limited to samples at advanced stages of weathering, while the Ce-rich types were found solely in samples from oxyhydroxide-rich zones. Fractionation of REE likely started at the early stages of weathering, but became evident only at the advanced stages. Characteristics of REE patterns, especially the direction (negative or positive) and extent of Ce-anomalies, correlated very well with the appearance and abundance of Mn-oxyhydroxides, and were attributed to the co-existence of distinct micro-environmental conditions within the profile. These conditions resulted from two major competing processes, “leaching and fixation” and “oxidation (precipitation) and reduction (dissolution)”, which operated simultaneously within the profile at any given stage of weathering.  相似文献   

The morphology and chemistry of K-feldspar megacrysts from Ikizdere Pluton: evidence for acid and basic magma interactions in granitoid rocks, NE-Turkey     

O Karsli  F Aydin 《Chemie der Erde / Geochemistry》2004,64(2):155-170

Ikizdere Pluton consists of granite, granodiorite, tonalite, monzonite, quartz monzonite containing pinkish colored K-feldspar megacrysts (KFMs). The crystal sizes of the KFMs range from 1 to 4 cm. The lath-shaped megacrysts are uniformly (i.e., randomly) distributed in the host plutonic rocks and have mafic and felsic inclusions whose crystal sizes are smaller than 1 mm. The crystal inclusions are biotite, slightly annitic in composition with X_Mg[=Fe_tot/(Fe_tot+Mg)]=0.50-0.58, amphibole (magnesio-hornblende, X_Mg[=Mg/(Mg+Fe_tot)]=0.70-0.79), iron-titanium oxide (low titanium magnetit and ilmenite), plagioclase (Ab₇₅₋₂₅An₆₅₋₃₅) and as minor quartz. The compositions of the KFMs range from Or₉₅Ab₅An₀ to Or₈₂Ab₁₇An₁. BaO contents of the megacrysts increase from core to rim. The mafic and felsic inclusions are compositionally similar those of the host rocks.The chemical and textural features of K-feldspar are typical for megacrysts that grew as phenocrysts in dynamic granitoidic magma systems. The overgrowth of KFMs and mafic magma injections (magma mixing) may be related to temperature, pressure and compositional fluctuations in the magma chamber. Remnant of earlier formed K-feldspar crystals remain in the felsic magma system, while the mafic injection can decompose some earlier precipitated KFMs. The remnant of K-feldspar remaining after mafic injection are overgrown by rapid diffusion of Ba, K and Na elements in liquid phase, during the later stages of crystallization of the host magma.  相似文献   

iSERVO: Implementing the International Solid Earth Research Virtual Observatory by Integrating Computational Grid and Geographical Information Web Services     

Mehmet Aktas  Galip Aydin  Andrea Donnellan  Geoffrey Fox  Robert Granat  Lisa Grant  Greg Lyzenga  Dennis McLeod  Shrideep Pallickara  Jay Parker  Marlon Pierce  John Rundle  Ahmet Sayar  Terry Tullis 《Pure and Applied Geophysics》2006,163(11-12):2281-2296

We describe the goals and initial implementation of the International Solid Earth Virtual Observatory (iSERVO). This system is built using a Web Services approach to Grid computing infrastructure and is accessed via a component-based Web portal user interface. We describe our implementations of services used by this system, including Geographical Information System (GIS)-based data grid services for accessing remote data repositories and job management services for controlling multiple execution steps. iSERVO is an example of a larger trend to build globally scalable scientific computing infrastructures using the Service Oriented Architecture approach. Adoption of this approach raises a number of research challenges in millisecond-latency message systems suitable for internet-enabled scientific applications. We review our research in these areas.  相似文献   

The use of Brazilian Test as a Quantitative Measure of Rock Weathering     

A. Aydin  A. Basu 《Rock Mechanics and Rock Engineering》2006,39(1):77-85

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Permeability upscaling of fault zones in the Aztec Sandstone,Valley of Fire State Park,Nevada, with a focus on slip surfaces and slip bands     

Ramil Ahmadov  Atilla Aydin  Mohammad Karimi-Fard  Louis J. Durlofsky 《Hydrogeology Journal》2007,15(7):1239-1250

The effect of open and filled slip surfaces on the upscaled permeability of two fault zones with 6 and 14 m strike-slip in an eolian Aztec Sandstone, Nevada, USA is evaluated. Each fault zone is composed of several fault components: a fault core, bounded by filled through-going slip surfaces referred to as slip bands, and a surrounding damage zone that contains joints and deformation bands. Slip band geometry, composition, and petrophysical properties are characterized. Measurements and modeling show that slip band permeabilities can vary over 12 orders of magnitude depending on the degree of fill within the slip bands. The slip bands along with other fault zone components are represented in finite volume numerical calculations and the impact of various slip-band representations on upscaled fault zone permeability is tested. The results show 2 orders of magnitude variation in upscaled fault zone permeability in the fault-normal direction and a factor of 2 variation in the fault-parallel direction. The numerical results presented here are compared to the earlier numerical results in which structured Cartesian grids were used for the numerical simulations, and are in qualitative agreement with earlier calculations but use about a factor of 250–400 fewer numerical cells.  相似文献   

Curie Point Depth Investigation of Central Anatolia,Turkey     

Abdullah?AtesEmail author  Funda?Bilim  Aydin?Buyuksarac 《Pure and Applied Geophysics》2005,162(2):357-371

The residual aeromagnetic total field intensity anomalies in central Anatolia were calculated from the regional aeromagnetic anomalies surveyed by the Mineral Research and Exploration (MTA) of Turkey. The residual aeromagnetic data were analyzed to produce Curie point estimates by the method of OKUBO et al. (1985). The Curie point depth of central Anatolia varies from 7.9 km and 22.6 km. The shallowest Curie point depths were observed around the Cappadocia and Erciyes Volcanic complexes in central Anatolia. A good correlation was deduced between the Curie point depths and the heat-flow data measured previously, which is most certainly important for the geothermal resources of the region. The shallow Curie point depths also correlate well with the hot spring locations in central Anatolia.  相似文献   

Interaction of multiple cracks and formation of echelon crack arrays     

Yijun Du  Atilla Aydin 《国际地质力学数值与分析法杂志》1991,15(3):205-218

Fracturing of rock under compression is a product of a series of processes, including nucleation, growth, interaction and coalescence of multiple microcracks. The formation of echelon arrays of microcracks and macrocracks is one of the crucial rings in the processes. We use a superposition and asymptotic approximation technique to analyse the interaction of multiple cracks with various geometrical configurations. It is shown that crack geometry has a strong influence on crack interaction. Echelon crack arrays produce the strongest interaction and are the preferred geometrical configuration for multiple cracks prior to the formation of through-going shear fractures. This technique provides parameter-dependent global behaviour, and is more efficient and easier to use.  相似文献   

Tunnelling in difficult ground: a case study from Dranaz tunnel, Sinop, Turkey     

A. Aydin  A. Ozbek  I. Cobanoglu 《Engineering Geology》2004,74(3-4):293-301

This paper presents a case study of the instability mechanisms, and the excavation sequence, re-qualification and reinforcement methods adopted to pass through a short segment of a nearly 2-km tunnel built as part of a new 55-km state highway in northern Turkey. The instability problems were encountered during tunnel excavation due to the failure to recognize the fact that alteration in stress field and resulting deformation could cause dilation and increase in the permeability of claystone-shale layers and local fault gouge zones, and in turn significant reduction in shear strength. Change in natural drainage pattern and capillarity exacerbated saturation and the consequent strength reduction. The 92-m³ loose material flowed into the tunnel due to the collapse and caused 2.5 months of delay in completion of the tunnel. Longitudinal and oblique cracks observed in shotcrete were attributed to the reduction in modulus upon saturation, which caused a large cumulative deformation of approximately 110 mm at a section about 30 m behind the collapse face.

It is concluded that early detection or prediction of potentially problematic zones (via probe drilling and monitoring) in tunnelling is of paramount importance, especially through mixed or difficult ground conditions characterized by alternating layers, folding, faulting and localized zones of high water pressure. Because mechanical detection methods cannot be fully relied upon, availability of experienced personnel to predict and deal with such instability problems effectively and promptly is the best insurance for successful completion of tunnelling contracts.  相似文献