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An earthquake of magnitude 7.2 on the Richter scale occurred on 12 November 1999 in the Düzce-Bolu region of Turkey. The region was also hit approximately 3 months before during the devastating Kocaeli earthquake of 17 August 1999. Besides high casualties and damage to various engineering structures and buildings, slope and embankment failures on the highway and the country roads occurred. In this study, the authors are concerned with the back-analysis of an embankment failure that occurred on the four lanes E-5 highway connecting Ankara to Gstanbul at Bakacak in the Bolu Province during the 1999 Düzce earthquake. Both pseudo-dynamic and dynamic limiting equilibrium methods are used to back analyse the conditions for the initiation of failure and also displacement responses of the embankment during the earthquake shaking. After having given a brief summary of the investigations on the post-failure state, the geology and geotechnical characteristics of the site, and the dynamic limiting equilibrium method developed and used for analyses are described. The results of the back-analysis based on a pseudo-dynamic approach, revealed that the maximum ground acceleration to initiate the failure of the embankment was probably about 0.125 g. On the other hand, the application of a method for computing the displacement and velocity responses of the failed embankment showed that the failure was possible when the embankment was subjected to ground accelerations similar to that recorded at the Düzce station. In addition, the computations also revealed that the time history of accelerations could be very important for the failure of slopes and embankments. 相似文献
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Underground cities and semi-underground settlements, most of which are 1500 years at least, exist in the Cappadocia Region of Turkey. These man-made rock structures are carved in soft tuffs and the best examples of long-term performance of man-made structures in the field of rock engineering. The tuffs also have good thermal isolation properties to be used as housing and storage of foods. In this article, the authors are only concerned with physical and short-term mechanical characteristics due to the wide-spectrum of the theme and the in situ characterization of the Cappadocia tuffs, and the results of investigations are presented. In addition, a critical overview on possible engineering geological problems at Cappadocia with mechanical aspects of historical and modern rock structures and their implications in rock engineering is made. From the experimental results in the field, it is evident that the engineering characteristics of these rocks do not show significant changes in vertical and horizontal directions. However, they are prone to atmospheric conditions. In addition, temperature and humidity measurements at different floors of the underground cities and various parts of semi-underground settlements indicated that variations in climatic conditions of the openings are very small when compared to those outside the ground surface. 相似文献
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D. M. Cocârţă S. Neamţu A. M. Reşetar Deac 《International Journal of Environmental Science and Technology》2016,13(8):2025-2036
Human activities have progressively increased in recent years. Consequently, significant environment deterioration resulted. Soils have a particularly varied vulnerability to heavy metal pollution, especially in the vicinity of industrial areas. Heavy metal contamination of soil may induce risks and hazards to humans and the ecosystem, while toxic metals in soil can severely inhibit the biodegradation of organic contaminants. This paper is focused on human health risk assessment from extremely contaminated soil with heavy metals, mainly with carcinogenic elements. The study refers to an agricultural area in the vicinity of an old metallurgical processing industrial facility. The contaminants evaluated in the present paper are beryllium (Be), cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb). Contamination level is pointed out through laboratory analysis results of soil samples taken from 0–0.2 m, 0.2–0.4 m soil layers and up to 2.1 m soil depth. Some heavy metal concentrations (Cd, Cr and Pb) exceed the intervention thresholds for sensitive areas, as they are stipulated in the national regulation in Romania. The identified average concentration levels of Cd, CrVI and Pb in the first layer of the investigated land are 23.83, 7.71 and 704.22 mg/kgd.w, respectively. The results show that the potential risk of human health is relevant (higher than the acceptable one after World Health Organization) and a possible solution for the remediation should become a major concern for the investigated area. 相似文献
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The equations of motion for the coupled dynamics of a small liferaft and fast rescue craft in a surface wave are formulated in two dimensions using the methods of Kane and Levinson [1985. Dynamics: Theory and Applications. McGraw-Hill Inc., New York]. It is assumed that the motion normal to the wave surface is small and can be neglected, i.e. the bodies move along the propagating wave profile. The bodies are small so that wave diffraction and reflection are negligible. A Stokes second order wave is used and the wave forces are applied using Morison's equation for a body in accelerated flow. Wind loads are similarly modelled using drag coefficients. The equations are solved numerically using the Runge–Kutta routine “ode45” of MATLAB®. The numerical model provides guidelines for predicting the tow loads and motions of small craft in severe sea states. 相似文献
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Extreme rainfalls in SE South America 总被引：1，自引：0，他引：1
Heavy rainfall trends in a region of south-eastern South America during 1959–2002 were discussed using daily data of 52 meteorological stations of Argentina, Brazil and Uruguay. Changes in intensity and frequency were both studied with different statistical tests and approaches to check the significance of trends of single and regional aggregated rainfall series. There were predominant positive trends in the annual maximum rainfalls, as well as a remarkable increment in the frequency of heavy rainfalls over thresholds ranging from 50 to 150 mm. However, significant positive trends were not shown in the series of annual maximums and shown only in 15% to 30% of the series of frequencies over thresholds. This lack of significance is due to the high variability of heavy rainfalls in space and time, which makes difficult their capture by single rain gauges. Thus, when the assessment of the heavy rainfall indicators of intensity and frequency were conducted at the regional and sub-regional level, it showed significant trends, both in intensity and frequency over thresholds, with a clearer signal in central and eastern Argentina between 30° and 40° S. 相似文献