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   

Electrical resistivity tomography mapping of beachrocks: application to the island of Thassos (N. Greece)   总被引：1，自引：0，他引：1  

Psomiadis David  Tsourlos Panagiotis  Albanakis Konstantinos 《Environmental Earth Sciences》2009,59(1):233-240

Electrical resistivity tomography (ERT) technique is widely used in mapping subsurface electrical properties. In this study, ERT was used to map a beachrock outcrop, extended both inland, under beach sediments, and seawards, on and under seafloor sediments. Mapping of beachrock is considered important because it can help evaluate the lateral and vertical extend of the formation. Fast and reliable mapping of beachrocks may contribute in several applications like engineering and construction, coastal management, recreational reformation as well as scientific approaches like coastal evolution research, and palaeo-environmental studies. The outcome of the survey was the mapping of the formation with centimeter precision, especially towards the sea. Special processing was applied to the data in order to constrain the inversion procedure to include the known sea water layer.  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   

Maximum Likelihood Estimation of Seismic Hazard for Sweden     

Andrzej Kijko  Efthimios Skordas  Rutger Wahlström  Päivi Mäntyniemi 《Natural Hazards》1993,7(1):41-57

The maximum magnitude, the activity rate, and the Gutenberg-Richterb parameter as earthquake hazard parameters, have been evaluated for Sweden. The maximum likelihood method permits the combination of historical and instrumental data. The catalog used consists of 1100 earthquakes in the time interval 1375–1989. The extreme part of the catalog contains only the strongest historical earthquakes, whereas the complete part is divided into several subcatalogs, each assumed complete above a specified threshold magnitude. The uncertainty in magnitude determination was taken into account. For southern Sweden, the calculations giveb-values of 1.04 (0.05) for the whole area south of 60° N and 0.98 (0.06) for a subregion of enhanced seismicity in the Lake Vänern area. For the whole area north of 60° N, theb-value is 1.35 (0.06) and for the seismicity zone along the Gulf of Bothnia 1.26 (0.06). The number of annually expected earthquakes with magnitude equal to or larger than 2.4 [M_L(UPP) or M_M(UPP)] is 1.8 for the whole southern Sweden, 1.3 for the Lake Vänern region, 3.7 for northern Sweden, and 2.4 for the region along the Gulf of Bothnia. The maximum expected regional magnitude is calculated to 4.9 (0.5) for a time span of 615 years for southern Sweden and the Lake Vänern subregion, and 4.3 (0.5) for a time span of 331 years for northern Sweden and the Gulf of Bothnia subregion. However, several historical earthquakes with magnitude above 5 in nearby areas of Norway indicate that the seismic potential may be higher.  相似文献   

Possible implications of climatic variability on the presence of capelin (Mallotus villosus) off the Norwegian coast     

Konstantinos I. Stergiou 《Climatic change》1991,19(4):369-391

The distribution of capelin in the southern Barents Sea shifts in the east-west direction in response to warming or cooling trends. The capelin arrives at the spawning grounds earlier and spawning takes place in deeper water in cold years as compared to warm years. Although the ultimate regulators of capelin distribution/abundance in the Barents Sea may involve complex interactions/responses between capelin and abiotic and biotic variables, water temperature was found to be a successful predictor and proximate regulator of capelin distribution/ abundance in that area.It has been maintained that capelin did not visit the Norwegian coastal waters during the turn of the 18th century and in 1830–1840. Yet, meteorological, oceanographic and ecological data hitherto presented provide cumulative evidence that capelin migrated to the Norwegian spawning grounds during both periods. Nevertheless, capelin arrived early in the year and remained and spawned further offshore in deeper waters. Since capelin in earlier fisheries were fished by means of land-fixed nets, the size of the catch depended on access by the capelin to the immediate coastal fishing areas. Thus, capelin were not accessible to Norwegian fishermen.  相似文献