MRS applicability for a study of glacial sedimentary aquifers in Central Jutland, Denmark   总被引：6，自引：0，他引：6  

Konstantinos Chalikakis  Mette Ryom Nielsen  Anatoly Legchenko 《Journal of Applied Geophysics》2008,66(3-4):176

Intensive geophysical measurements are currently being carried out in Denmark to comply with the Danish Government's environmental plans of dense hydrogeological mapping to ensure high quality non-treated drinking water supply based solely on groundwater. A MRS-TDEM combined geophysical survey was conducted to measure the applicability and the contribution of MRS to running drilling programs.Despite complicated electromagnetic noise conditions, the MRS method proved to be applicable in the Danish context. An example of the practical application of MRS combined with TDEM in two selected areas of the former County of Vejle in Denmark, demonstrates the efficiency of the technique. The MRS results clearly suggest optimal locations for water supply boreholes within subsurface structures with homogeneous resistivity conditions mapped by TDEM. These results reveal the interest of using MRS as a new geophysical tool for the Danish water supply policy, which can provide a foundation for optimising drilling site locations within areas with resistivities in the aquifer range. However, more MRS soundings need to be carried out in order to improve MRS calibration in the Danish context, which will allow quantitative MRS characterization of aquifers.  相似文献   

Modified capacity design rule for columns in tall steel MRFs with linear viscous dampers within the framework of Eurocode 8     

Konstantinos Kariniotakis  Theodore L. Karavasilis 《Bulletin of Earthquake Engineering》2018,16(2):917-932

Seismic design codes enforce a set of capacity design rules for steel moment-resisting frames (MRFs) to promote a ductile sway plastic mechanism that involves plastic hinges in beams and column bases. Previous research showed that these capacity design rules may not be effective for tall steel MRFs with viscous dampers under strong earthquakes due to high axial forces in columns. To address this issue, steel MRFs with linear viscous dampers of different stories are designed according to Eurocode 8 along with using a slightly modified conservative capacity design rule. According to this rule, the axial force for the capacity design of a column in the force path of viscous dampers is calculated as the envelope of the axial force from the peak drift state, and, the axial force from the peak velocity state times a scale factor. This envelope axial force value along with the bending moment and shear force from the peak drift state are used to carry out the capacity design of the column by using the formulae of Eurocode 8, i.e. in the same way with a column of a steel MRF without dampers. Incremental dynamic analyses for 44 earthquake ground motions show that the modified conservative capacity design rule results in steel MRFs with viscous dampers that have plastic mechanisms similar to those of steel MRFs without dampers. Moreover, the proposed capacity design rule becomes stricter for buildings with more than 10 stories to address that available analysis methods for structures with dampers underestimate the peak damper forces in the lower stories of yielding tall steel MRFs. More work is needed to extend the findings of this work to the case of steel MRFs with nonlinear viscous dampers.  相似文献   

On‐line hybrid test method for evaluating the performance of structural details to failure          下载免费PDF全文

Konstantinos A. Skalomenos  Masahiro Kurata  Masayoshi Nakashima 《地震工程与结构动力学》2018,47(3):555-572

A test environment to evaluate the seismic performance of gusset plate connections intended for steel braced frames is proposed. The developed test method combines the substructuring techniques with finite element analysis methods in an on‐line hybrid scheme. Numerical substructure analysis is conducted on bracing members, while bracing connections are treated as experimental substructures. A force‐displacement combined control imposed with the aid of 2 jacks ensures physical continuity between the analysis and test. The rotational behavior of gusset plate connections subjected to large inelasticity and varying axial loading until fracture is investigated. Two gusset plate details were designed and tested to verify the efficiency of the proposed method. The test method is rational, and smooth operation is achieved. The test results revealed the advantage of the developed on‐line hybrid test method in exploring the ultimate capacity of bracing connections.  相似文献   

Geochemical and Sr-Nd isotopic evidence for petrogenesis and geodynamic setting of Lower-Middle Triassic volcanogenic rocks from central Greece: Implications for the Neotethyan Pindos ocean     

Castorina  Francesca  Magganas  Andreas  Masi  Umberto  Kyriakopoulos  Konstantinos 《Mineralogy and Petrology》2020,114(1):39-56

Mineralogy and Petrology - Geochemistry and Sr-Nd isotopes were determined in Triassic calcalkaline metalava and metapyroclastic rocks from Attica and Argolida, central Greece, to ascertain their...  相似文献   

Estimation of SCS Curve Number variation following forest fires     

Konstantinos X. Soulis 《水文科学杂志》2018,63(9):1332-1346

The Soil Conservation Service Curve Number (CN) method is routinely used to estimate the effects of forest fires on hydrological response. However, despite recent efforts, CN values are still not well known for burned conditions. A major forest fire in Attica, Greece, which affected the Lykorrema stream experimental watershed, provided an opportunity for the estimation of post-fire CN variation using detailed pre-fire and post-fire rainfall–runoff datasets. The CN values for both periods were estimated and compared using a wide range of available methods. Methods considering the spatial variability of soil-cover complexes were also used to investigate the effect of spatial heterogeneity. The post-fire watershed response changed from complacent to standard. Direct runoff depths and peak flows increased by a factor of more than 7.7 and 11.8, respectively. On average, the estimated post-fire CN values for the studied soil-cover complexes increased by about 25 units. This study may assist the improvement of existing post-fire hydrological assessment tools.  相似文献   

Fragility function development and seismic loss assessment of expansion joints     

Yu Otsuki  Masahiro Kurata  Konstantinos A. Skalomenos  Yoshiki Ikeda  Motoki Akazawa 《地震工程与结构动力学》2019,48(9):1007-1029

Expansion joints are used as a special connection equipment between adjacent buildings to accommodate the relative motions generated by wind, thermal, or earthquake loads, but they often exhibit damage during severe earthquakes. The level of damage and safety factors required to avoid loss of function are not well considered in current design practices. The objective of this paper is to provide quantitative information on the seismic damage probability of common expansion joints and the associated repair costs. The designer and engineer can refer to this information as a basis for decision making in the selection of expansion joints. Four common types of expansion joints are considered: high- and standard-performance floor and wall expansion joints, whose damage states have been evaluated recently by the authors through shaking table tests. First, the fragility functions of expansion joints for seven damage patterns are developed utilizing the test results. Next, the vulnerability of expansion joints installed between adjacent building models is assessed via incremental dynamic analysis. The recommended level of safety factor to ensure the function of expansion joints is discussed. Finally, a procedure for cost-effective selection of expansion joints is introduced, where case studies are examined using buildings with different characteristics. The presented results are deemed to be beneficial for improving the design practice of expansion joints and for reducing future seismic loss.  相似文献   

The geodynamic and limnological evolution of Balkan Lake Ohrid,possibly the oldest extant lake in Europe     

Bernd Wagner  Paul Tauber  Alexander Francke  Niklas Leicher  Steven A. Binnie  Aleksandra Cvetkoska  Elena Jovanovska  Janna Just  Jack H. Lacey  Zlatko Levkov  Katja Lindhorst  Katerina Kouli  Sebastian Krastel  Konstantinos Panagiotopoulos  Arne Ulfers  Dušica Zaova  Timme H. Donders  Andon Grazhdani  Andreas Koutsodendris  Melanie J. Leng  Laura Sadori  Mirko Scheinert  Hendrik Vogel  Thomas Wonik  Giovanni Zanchetta  Thomas Wilke 《Boreas: An International Journal of Quaternary Research》2023,52(1):1-26

Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584-m-long DEEP sediment succession and a comparison to a 197-m-long sediment succession from the Pestani site ~5 km to the east in the lake, where drilling ended close to the bedrock, to unravel the earliest history of Lake Ohrid and its basin development. ²⁶Al/¹⁰Be dating of clasts from the base of the DEEP sediment succession implies that the sedimentation in the modern basin started at c. 2 Ma. Geophysical, sedimentological and micropalaeontological data allow for chronological information to be transposed from the DEEP to the Pestani succession. Fluvial conditions, slack water conditions, peat formation and/or complete desiccation prevailed at the DEEP and Pestani sites until 1.36 and 1.21 Ma, respectively, before a larger lake extended over both sites. Activation of karst aquifers to the east probably by tectonic activity and a potential existence of neighbouring Lake Prespa supported filling of Lake Ohrid. The lake deepened gradually, with a relatively constant vertical displacement rate of ~0.2 mm a⁻¹ between the central and the eastern lateral basin and with greater water depth presumably during interglacial periods. Although the dynamic environment characterized by local processes and the fragmentary chronology of the basal sediment successions from both sites hamper palaeoclimatic significance prior to the existence of a larger lake, the new data provide an unprecedented and detailed picture of the geodynamic evolution of the basin and lake that is Europe’s presumed oldest extant freshwater lake.  相似文献   

New magnetic mineralogy and archaeointensity results from greek kilns and baked clays     

Vassileios Spatharas  Despina Kondopoulou  Elina Aidona  Konstantinos G. Efthimiadis 《Studia Geophysica et Geodaetica》2011,55(1):131-157

Seven archaeological sites in Northern Greece and a pottery assemblage from Ithaki Island (Ionian Sea) have provided material from kilns and a collection of baked clays. The whole dataset consists of 69 samples and covers a period of almost 4000 years. Although the majority of the samples was oriented, only few directions could be obtained, mostly due to small sample size and fragility. Detailed rock magnetic experiments identified magnetite/titano-magnetite and substituted magnetite as the main magnetic minerals. Variable amounts of haematite were detected in some cases. In three out of eight sites, multi-domain grains prevail, whereas single-, pseudo-single domain or mixtures are detected in the remaining five. The classical Thellier-Thellier palaeointensity method was applied to 94 specimens. Following stringent acceptance criteria, 66 results from the 8 sites were considered successful and retained. These new results show a convergence with regional and global compilations and improve the knowledge of the past geomagnetic field behaviour in Greece.  相似文献   

Preliminary gas hazard evaluation in Greece     

D’Alessandro  Walter  Kyriakopoulos  Konstantinos 《Natural Hazards》2013,69(3):1987-2004

Natural Hazards - Like other geodynamically active areas, Greece is also affected by a large number of geogenic gas manifestations. These occur either in the form of point sources (fumaroles,...  相似文献   

Evaluation of a global ensemble flood prediction system in Peru     

Konstantinos Bischiniotis  Bart van den Hurk  Ervin Zsoter  Erin Coughlan de Perez  Manolis Grillakis  Jeroen C. J. H. Aerts 《水文科学杂志》2013,58(10):1171-1189

ABSTRACT

Flood early warning systems play a more substantial role in risk mitigation than ever before. Hydrological forecasts, which are an essential part of these systems, are used to trigger action against floods around the world. This research presents an evaluation framework, where the skills of the Global Flood Awareness System (GloFAS) are assessed in Peru for the years 2009–2015. Simulated GloFAS discharges are compared against observed ones for 10 river gauges. Forecasts skills are assessed from two perspectives: (i) by calculating verification scores at every river section against simulated discharges and (ii) by comparing the flood signals against reported events. On average, river sections with higher discharges and larger upstream areas perform better. Raw forecasts provide correct flood signals for 82% of the reported floods, but exhibit low verification scores. Post-processing of raw forecasts improves most verification scores, but reduces the percentage of the correctly forecasted reported events to 65%.  相似文献