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1.
The engineering aspects of the 4 March 1977 Romanian earthquake are presented. They are based upon a field investigation conducted by the writers in Bucharest and in southern Romania in collaboration with members of the Building Research Institute of Romania, during the period 25–31 March 1977. This report covers general observations, data and evaluation on the character of the earthquake, structural damage inflicted by it, performance of different types of buildings during the earthquake and relief operations. 相似文献
2.
The Upper Quaternary seismic stratigraphy and active faults of the Gulf of İzmit were investigated by means of high-resolution
shallow seismic profiling data in the source region of 1999 İzmit earthquake. High-resolution seismic reflection data correlated
with borehole data indicate that the stratigraphy of İzmit Bay consists of three distinct depositional sequences formed in
response to middle Pleistocene-Holocene sea-level changes. Reflector R, separating the pre-Holocene sequences (1 and 2) from
the Holocene sequence (3), represents an erosional unconformity produced by the subaerial fluvial erosion of the continental
shelves at the time of the last glacial maximum. Occasional, anomalous reflections (acoustic turbidity) observed within the
Holocene sequence are interpreted as gas accumulations. The maximum thickness of the Holocene sediments is found to be about
25 m. The isopach map of Holocene sediment implies that the thickness of the Holocene decreases from the east towards the
central and western basins of İzmit Bay. Two distinct fault systems are interpreted in İzmit Bay. The main fault system extending
roughly in an E-W direction along the Gulf of İzmit is an active right lateral strike slip fault with a normal component.
The secondary faults are normal faults striking in different directions and these are identified as being both active and
inactive. In addition, prominent compressive features are identified in the seismic cross-sections of some profiles acquired
to the east of Hersek Peninsula where the focal mechanisms of the aftershocks of the 1999 İzmit earthquake also reveal predominantly
reverse faulting mechanisms, as identified by a local dense seismic network. 相似文献
3.
Celalettin Özdemir Hayrunnisa Tezcan Serkan Sahinkaya Erkan Kalipci 《洁净——土壤、空气、水》2010,38(12):1152-1158
The removal of chemical oxygen demand (COD) and phenol from olive oil mill wastewaters (OOMW) was investigated experimentally by using conventional Fenton (CFP) and Fenton type processes (FTP) with zero valent iron (ZVI). Different operational parameters such as initial pH, Fe2+, Fe0, and H2O2 concentrations were examined. Kinetic studies in terms of COD and phenol removals for both CFP and FTP were performed. The original pH value (4.6) of OOMW for CFP was found as the optimum pH. The determined optimum conditions are [Fe2+] = 1500 mg L?1, [H2O2] = 1750 mg L?1, and pH = 4.6 for CFP; [Fe0] = 2000 mg L?1, [H2O2] = 2000 mg L?1, and pH = 3 for FTP. 82.4% COD and 62% phenol removals were performed under the optimum conditions by CFP, while 82% COD and 63.4% phenol were removed by FTP. According to the results of kinetic studies, it was observed that COD and phenol were removed by FTP more rapidly, compared to CFP. Consequently, it was determined that both CFP and FTP were effective processes for the pretreatment of OOMW. 相似文献
4.
This study uses support vector regression (SVR), a supervised machine learning algorithm, to model the average horizontal response spectrum as a nonparametric function of a set of predictor ground motion variables. Traditional ground motion prediction equations (GMPEs) are derived using parametric regression, where a fixed functional form is selected, and the model coefficients are determined by minimizing the errors on the training set. The SVR model is nonparametric; there is no need to assume a fixed functional form. Using nonlinear basis functions, the data points are mapped into a high dimensional feature space, where nonlinear input-output relationships can be expressed as a linear combination of nonlinear functions, using a subset of the data points. The combination weights are determined by minimizing the generalization error, using a formal mechanism to characterize the trade-off between the model complexity and the quality of fit to the data. Minimization of the generalization error instead of the fitting error leads to better generation to unseen data, and thus reduces the risk of over-fitting for a given number of data points. The SVR model is not based on a specific probability distribution, and is readily applicable to non-Gaussian data. An example application is presented for vertical strike-slip earthquakes, and the predictions from the SVR model are compared to the recently developed GMPEs. The results demonstrate the validity of the proposed model, and suggest that it can be used as an alternative to the conventional ground motion prediction models. 相似文献
5.
Design guidelines have traditionally oversimplified the vertical ground motion effects by defining a constant vertical‐to‐horizontal response spectral ratio (V/H). With the recognition that such practice is not always conservative, recent studies have proposed improvements to the representation of vertical seismic effects in design codes, based on empirical ground motion relations. Conventional empirical modeling requires selecting the functional form of the predictive model. Because of the complicated nature of ground motions, identification of the underlying function is a challenge. A related drawback to this approach is its high susceptibility to overfitting, especially with today's highly complex models. To address these issues, this paper proposes a nonparametric approach to characterize the vertical seismic effects. Using support vector machines, the V/H ratio is determined without an assumed functional form. The accuracy of the model is measured by adopting an epsilon‐insensitive residual function with a regularization term added to prevent overfitting. An example application using ground motion records from strike‐slip and normal faulting earthquakes is presented, and the results are compared with a current empirical model, for different magnitude, distance, and local soil conditions. The median V/H estimates from the two models are shown to be in good general agreement. The standard deviation estimates from the proposed model are consistently larger than the estimates from the empirical model. The results from this study show that the proposed method is a viable alternative and offers the opportunity to characterize vertical seismic effects without an assumed functional form. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
6.
S. Uzaşçı F. Tezcan F. B. Erim 《International Journal of Environmental Science and Technology》2014,11(7):1861-1868
Barium ion cross-linked alginate beads have shown great affinity to toxic hexavalent chromium ions in aqueous solution, in contrast to the traditionally used calcium alginate beads. Our adsorption experiments were carried out by the batch contact method. The optimal pH for removal was found to be pH 4. The equilibrium was established in 4 h, and the removal efficiency of chromium(VI) was found to be 95 %. The adsorption data were applied to Langmuir, Freundlich, Dubinin–Redushkevich (D–R), and Temkin isotherm equations. Both Langmuir and Freundlich isotherm constants indicated a favorable adsorption. The value of mean sorption energy calculated from D–R isoterm indicates that the adsorption is essentially physical. The high maximum chromium(VI) adsorption capacity was determined from the Langmuir isotherm as 36.5 mg/g dry alginate beads. The chromium(VI) adsorption data were analyzed using several kinetic models such as the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models, and the rate constants were quantified. Our study suggests that barium alginate beads can be used as cost-effective and efficient adsorbents for the removal of chromium(VI) from contaminated waters. 相似文献
7.
Mahmut Okyar Sedat Yılmaz Devrim Tezcan Hakan Çavaş 《Marine Geophysical Researches》2013,34(2):127-136
No detailed information has previously been available on the geological and geophysical characteristics of the sea floor and the underlying strata of Mersin Harbour, Northeastern Mediterranean Sea (Turkey). Continuous resistivity profiling (CRP) and borehole data from Mersin Harbour were used to interpret geoelectric stratigraphy of Neogene-Quaternary sediments in the area. This represents one of few such detailed case studies that have applied these valuable CRP techniques for the purpose of marine stratigraphic imaging. It was found that the Neogene-Quaternary sedimentary succession in the area consists of three geoelectric units (GU1, GU2, and GU3 from base to top). The lowest unit, GU1, has a resistivity value of greater than 20.0 ohm-m and consists of Miocene aged limestone and marl. The middle unit, GU2, is characterized by resistivity values ranging from 3.0 to 20.0 ohm-m. Its thickness is greater than 90 m, with the upper section being composed of stiff clay sequences which are Plio-Pleistocene in age. The uppermost unit, GU3, has resistivity values varying from 1.0 to 3.0 ohm-m. This unit displays a maximum thickness of 15 m, and is composed of Holocene muds together with gravel, sand, silt and clay (sometimes incorporating shells) materials of the Plio-Pleistocene age and their various mixtures, silty/clay limestone, and conglomerate sandstone. Comparisons of the geoelectric units with the depositional sequences interpreted from the available seismic data outwith, but close to, Mersin Harbour reveal that the geoelectric unit GU3 corresponds to the depositional sequences C (mainly Holocene) and B (mainly Plio-Pleistocene). The geoelectric unit GU2 partly correlates with the depositional sequence B which appears to be Plio-Pleistocene in age. The geoelectric unit GU1, which has not been encountered in previous seismic surveys, is a new discovery within Mersin Harbour. Limited correlation between the seismic and resistivity structures in the study area is attributed to differences in the acoustic impedance and resistivity contrasts of sub-bottom layers, as well as the penetration versus resolution performance of the systems. 相似文献
8.
Groundwater discharges from the intensively karstified Taurus Mountains to the Mediterranean Sea, either along the contact zone between the mountains and the Travertine Plateau (the Kirkgozler Springs, 15 m3/s), or through the travertine (e.g. the Dudenbasi Spring, 18 m3/s) and underneath it (unnamed submarine springs, unknown discharges). In an attempt to identify the hydraulic connections between the various outlet points, groundwater was analyzed for stable and radioactive isotopes, CFCs and He. The upgradient springs, belonging to the Kirkgozler–Dudenbasi system, were proven to be a mixture of recent and older water on the basis of their low 14C values (12–22.4 pmc), their exceptionally high He content (429–991 μcc/kg) and 3He:4He (R:Ra) ratios (1.471–2.602) and their measurable 3H and CFC contents (1.9–5.9 TU and 0.84 to 3.27 pmoles/kg, respectively). The older component probably contains an even lower amount of modern C. However, the undersaturation of the mixture with respect to calcite, its high CO2 content (up to 83 mg/L) and its enriched 13C values (−2.2 to −4.1‰) suggest intensive water/rock interactions, which would contribute 14C-devoid bicarbonates to the solution. Downgradient springs discharging along the Mediterranean coast contain groundwater contributions from higher altitudes, as evidenced by their depleted δ18O and δD composition with respect to the local precipitation; however, a larger portion of the recent water component could be contributed from direct precipitation on the travertine. This larger component is reflected in the increased 3H (3.4 to 8.4 TU) and 14C (32.7–63.6 pmc) contents, atmospheric He (43–82 pmoles/kg), R:Ra values (1.006–1.198) and CFC contamination of the water. 相似文献
9.
In this paper, soil-structure interaction studies are presented for buildings which collapsed at the Tofas automobile factory, Bursa, Turkey, during the 28 March 1970 Gediz earthquake. Acceleration response spectrum curves of the ground were determined using the vibrations of an after shock recorded by a Willmore velocity seismometer. These spectrum curves provide an essential source of information for establishing the reasons of collapse, as well as for explaining the relative response to the earthquake of various buildings in the factory area. The factory not only is 135 km away from the epicentre, but also is far outside the fifth degree damage intensity zone. The prime reason why a low value of ground acceleration caused such surprisingly heavy damage to modern reinforced concrete structures is concluded to be the resonance phenomenon arising from the natural period of the structures coinciding with the predominant period of the soil. 相似文献
10.
Based on a variety of case histories of site investigations, including extensive bore-hole data, laboratory testing and geophysical
prospecting, an empirical formulation is proposed for the rapid determination of allowable bearing capacity of shallow foundations.
The proposed expression consistently corroborates the results of the classical theory and is proven to be rapid and reliable.
It consists of only two soil parameters, namely, the in situ measured shear wave velocity, and the unit weight. The unit weight may be also determined with sufficient accuracy by means
of another empirical expression using the P-wave velocity. It is indicated that once the shear and P-wave velocities are measured in situ by an appropriate geophysical survey, the allowable bearing capacity as well as the coefficient of subgrade reaction and
many other elasticity parameters may be determined rapidly and reliably through a single step operation, not only for soils,
but also for rock formations. Such an innovative approach, using the seismic wave velocities only, is considerably cost- and
time-saving in practice. 相似文献