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631.
Lucie Novakova Milan Broz Jiri Zaruba Karel Sosna Jan Najser Lenka Rukavickova Jan Franek Vladimir Rudajev 《应用地球物理》2016,13(2):315-325
Underground storage systems are currently being used worldwide for the geological storage of natural gas (CH4), the geological disposal of CO2, in geothermal energy, or radioactive waste disposal. We introduce a complex approach to the risks posed by induced bedrock instabilities in deep geological underground storage sites. Bedrock instability owing to underground openings has been studied and discussed for many years. The Bohemian Massif in the Czech Republic (Central Europe) is geologically and tectonically complex. However, this setting is ideal for learning about the instability state of rock masses. Longterm geological and mining studies, natural and induced seismicity, radon emanations, and granite properties as potential storage sites for disposal of radioactive waste in the Czech Republic have provided useful information. In addition, the Czech Republic, with an average concentration radon of 140 Bq m?3, has the highest average radon concentrations in the world. Bedrock instabilities might emerge from microscale features, such as grain size and mineral orientation, and microfracturing. Any underground storage facility construction has to consider the stored substance and the geological settings. In the Czech Republic, granites and granitoids are the best underground storage sites. Microcrack networks and migration properties are rock specific and vary considerably. Moreover, the matrix porosity also affects the mechanical properties of the rocks. Any underground storage site has to be selected carefully. The authors suggest to study the complex set of parameters from micro to macroscale for a particular place and type of rock to ensure that the storage remains safe and stable during construction, operation, and after closure. 相似文献
632.
633.
Vitaliy D. Rusov Vladimir N. Vaschenko Elena P. Linnik Оksana T. Myhalus Yuriy A. Bondartchuk Vladimir P. Smolyar Sergey I. Kosenko Strachimir Cht. Mavrodiev Boyko I. Vachev 《Journal of Atmospheric and Solar》2010,72(5-6):389-397
The solution of energy-balance model of the Earth global climate and the EPICA Dome C and Vostok experimental data of the Earth surface palaeotemperature evolution over past 420 and 740 kyr are compared.In the framework of proposed bifurcation model (i) the possible sharp warmings of the Dansgaard-Oeschger type during the last glacial period due to stochastic resonance is theoretically argued; (ii) the concept of climatic sensitivity of water in the atmosphere, whose temperature instability has the form of so-called hysteresis loop, is proposed, and based on this concept the time series of global ice volume over the past 1000 kyr, which is in good agreement with the time series of δ18O concentration in the sea sediments, is obtained; (iii) the so-called “CO2 doubling” problem is discussed. 相似文献
634.
Jean-Louis Le Mouël Vladimir Kossobokov Vincent Courtillot 《Journal of Atmospheric and Solar》2010,72(1):62-76
We analyze the longest temperature series from Prague, Bologna and Uccle. We partition daily minimum and maximum temperatures and their differences in two subsets as a function of high vs low solar activity, using the superimposed epochs method. Differences display patterns with significant amplitudes and time constants ~3 months. These are recognized in all stations and are stable against a change in the analyzed period. Amplitude of variations is ~1 °C. Differences between average annual values corresponding to high vs low activity periods are also ~1 °C. Solar activity may account for these long-term temperature variations. These variations also present local characteristics, which may render identification of a global correlation delicate. We discuss possible physical mechanisms by which solar variation could force climate changes (e.g. through solar activity itself, the EUV part of the solar flux, cosmic rays, the downward ionosphere-earth current density, etc.). 相似文献
635.
Lidija Krstevska Ljubomir Tashkov Vladimir Gocevski Mihail Garevski 《Bulletin of Earthquake Engineering》2010,8(2):421-450
The seismic stability of the facade brick-masonry walls of the machinery building of the Beauharnois powerhouse near Montreal,
Quebec, Canada were investigated numerically by use of non-linear models and applying experimental methods on site and on
the IZIIS’ seismic shake-table. The dynamic properties of the machinery building were obtained by ambient vibration measurements.
Based on these results, a model of a representative part of the building, consisting of steel frames and brick masonry wall,
was designed and constructed to the reduced scale at the IZIIS’ Dynamic Testing Laboratory and then tested on the two-component
shake-table. The geometry of the original structure was completely scaled to 1/3, consisting of many realistically simulated
details such us: brick layers, steel columns, openings, window frames, steel connectors between brick layers, number of layers,
brick dimensions, etc. The material used for the model was: original steel for the frame structure and bricks of reduced mechanical
properties for the masonry wall, close to the similitude requirements according to the Backingham’s theorem, valuable for
adequate artificial—mass simulation model as well as true replica simulation model. More than 50 seismic tests were performed
considering the design earthquake Nahanni NWT, H1, with a time scaling factor of 31/2, and acceleration scaling factor 1, according to the model design rules. The intensity of the applied input earthquake excitation
was from 0.05 to 1.2 g. The design peak acceleration of Nahanni earthquake was 0.2 g. The cracks development was stated at
0.7 g input acceleration. These were concentrated around the openings. No collapse happened even under the strongest earthquake
input. The numerical part of this paper deals with formulation/application of the critical plane approach to seismic analysis
of masonry structures. Starting with the constituents, i.e. mortar and bricks, the macroscopic strength properties of masonry
were established based on numerical homogenization. Generally, based on all the performed experimental tests, considering
some simplifications and assumptions in the constructing details, as well as in the design of the model, the global conclusion
is that the existing wall is very well incorporated in the steel structure of the powerhouse. The complementary stiffness
of the steel frame and the brick masonry wall produces interactive deformation of the system. Only local cracking and relative
displacement between the wall and the steel frames could be expected in the case of a strong earthquake. 相似文献
636.
Joachim Miksat Kuo-Liang Wen Vladimir Sokolov Chun-Te Chen Friedemann Wenzel 《Bulletin of Earthquake Engineering》2010,8(4):847-858
Taipei, the capital of Taiwan, suffered from destructive earthquakes four times during the 20th century (M
L = 7.3 on April 15, 1909; M
L = 6.8 on November 15, 1986; the Chi–Chi M
L = 7.3 earthquake on September 21, 1999; and M
L = 6.8 on March 31, 2002). Analysis of recorded data shows a strong dependence of spectral amplification in the Taipei Basin
on earthquake depth and azimuth. At low frequencies (f < 3 Hz) significant larger amplifications are observed for shallow earthquakes as compared to intermediate depth events.
The former ones also display strong azimuthal dependence. As structures with large response periods such as bridges and tall
buildings are sensitive to these low frequencies the understanding of the associated wave effects within the basin and their
role for site effect amplification is critical. The tool we employ is 3D finite-difference modeling of wave propagation of
incident wave fronts. The available detailed model of the basin allows studying the wave effects. Modeling clearly reveals
that basin edge effects as observed in data are related to surface wave generation at the basin edges with a high degree of
azimuthal dependency. The reproduced site amplification effects are in qualitative agreement with the observations from strong
motion data. 相似文献
637.
Determination of impedances is necessary in order to eliminate some shortcoming of our knowledge about structures of the exciting
source fields and their fickleness. The experimental impedances for induction soundings result from the impedance boundary
conditions or heuristic models. The simplified models give just a rough idea of their domain of applicability. Impedances
can depend on many factors, including the exciting field structures of several source types which are present in the period
range of the mantle soundings (104−4×108 s). The problem in the mantle investigations arises if impedances measured by different methods have to be jointly inverted
in order to essentially prolongate the analyzed period range and hence to increase the reliability and depth of induction
soundings on land. The subject of our work is an analysis of the known magnetotelluric and magnetovariation impedances to
suggest a physically substantiated approach for their joint inversions. 相似文献
638.
Mauricio Parra Andrés Mora Carlos Jaramillo Vladimir Torres Gerold Zeilinger Manfred R. Strecker 《Basin Research》2010,22(6):874-903
In order to evaluate the relationship between thrust loading and sedimentary facies evolution, we analyse the progradation of fluvial coarse‐grained deposits in the retroarc foreland basin system of the northern Andes of Colombia. We compare the observed sedimentary facies distribution with the calculated one‐dimensional (1D) Eocene to Quaternary sediment‐accumulation rates in the Medina wedge‐top basin and with a three‐dimensional (3D) sedimentary budget based on the interpretation of ~1800 km of industry‐style seismic reflection profiles and borehole data. Age constraints are derived from a new chronostratigraphic framework based on extensive fossil palynological assemblages. The sedimentological data from the Medina Basin reveal rapid accumulation of fluvial and lacustrine sediments at rates of up to ~500 m my?1 during the Miocene. Provenance data based on gravel petrography and paleocurrents reveal that these Miocene fluvial systems were sourced from Upper Cretaceous and Paleocene sedimentary units exposed to the west in the Eastern Cordillera. Peak sediment‐accumulation rates in the upper Carbonera Formation and the Guayabo Group occur during episodes of coarse‐grained facies progradation in the early and late Miocene proximal foredeep. We interpret this positive correlation between sediment accumulation and gravel deposition as the direct consequence of thrust activity along the Servitá–Lengupá faults. This contrasts with one class of models relating gravel progradation in more distal portions of foreland basin systems to episodes of tectonic quiescence. 相似文献
639.
Marchenkov Konstantin I. Zharkov Vladimir N. Nikishin Anatoly M. 《Earth, Moon, and Planets》1990,(1):81-98
The data obtained for the heights of the relief and the external gravitational field of Venus for spherical harmonics with degree and order up to 18 allow one to start theoretical analysis of the crust-mantle boundary (Venusian Moho) and stress state of the planetary interior. We suppose that Venusian convection is confined by floating massive crust. Apparently the convection in the upper mantle of Venus is separated from that one in the lower mantle and its lateral scale must be essentially smaller than on Earth. So, the convection is reflected to a larger degree of the gravitational field of the planet than for Earth. The spherical harmonic expansion of the topography for Venus correlates with corresponding expansion of the non-equilibrium part of the gravitational potential for n = 3–18. At the same time the relief of Venus is significantly compensated. It is reasonable to suppose that the gravity field for these harmonics is due to crustal thickness variations and, probably, to variations of crustal density. Thus, in the proposed scheme the Moho's relief causes the partial isostatic compensation of the topography.All calculations are carried out for the series of realistic models of Venus taking into consideration an asthenosphere. The asthenosphere is modeled either by a weakened (shear modulus is reduced), or by a liquid inviscid layer. We also suppose that the asthenosphere extends from the base of crust to a depth of 418 km, and the density contrast across the Moho boundary is –0.4 g * cm–3. If the actual density contrast across the Moho is less than the supposed one by some factor, then one must increase the amplitudes of the roots and inverse roots by the same factor. The results for the Moho's relief and stresses in the crust are presented for the case of the mean thickness of the crust of 50 km, which satisfies the probable upper (connected with phase transitions in waterless basalts) and lower (appearing in the framework of our interpretation) limits.On the whole, the crust-mantle boundary on Venus is evidently smooth, and the stress level in the crust is appreciably smaller than the crustal stresses on the Earth. The strong sensitivity of the stresses character to the parameters of the model of external layers of Venus together with geological data allow us to begin a preliminary investigation of the tectonical structure and geodynamics of the planet.'Geology and Tectonics of Venus', special issue edited by Alexander T. Basilevsky (USSR Acad. of Sci. Moscow), James W. Head (Brown University, Providence), Gordon H. Pettengill (MIT, Cambridge, Massachusetts) and R. S. Saunders (J.P.L., Pasadena). 相似文献
640.
Vladimir N. Shinkin 《Celestial Mechanics and Dynamical Astronomy》1997,68(2):105-120
For the general and restricted elliptic planetary spatial three-bodyproblems under the oblateness of the central body and at both third-orderorbital and secondary resonances, the analytical solutions are obtained bythe use of the Weierstrass functions with an accuracy of the fourth-degreeterms in the eccentricities and inclinations. The behaviour of solutions isstudied on the phase plane. 相似文献