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31.
32.
液化土层对地表加速度反应谱的影响 总被引:4,自引:0,他引:4
采用一种改进的有效应力方法研究土层液化对地表加速度反应谱的影响,分析中考虑了砂层的厚度、埋深和输入地震波的幅值和波型等因素。分析结果表明,土层液化使地表加速度反应谱的特征周期至少延长0.1秒以上,使原Ⅱ类场地变为Ⅲ类场地,高烈度时易变成Ⅳ类场地,反应谱中周期0.8秒-1.0秒是液化砂层加震或减震的一个分界点,液化对反应谱短周期分量具有一定的减震作用,而对长周期分量有非常显著的放大作用。 相似文献
33.
地震动作用下滑坡稳定性分析 总被引:2,自引:0,他引:2
李忠生 《水文地质工程地质》2004,31(2):4-8
应用地震危险性分析理论和地震动人工合成技术,给出Newmark法中所需的地震动时程。通过滑坡实例计算,得出了坡体中地震动峰值加速度与深度存在负指数关系;坡体对地震动放大倍数与坡体厚度近似呈线性关系。通过对Ne wmark法中不同地震动时程作用位置的计算对比,发现使用地面地震动时程得到的结果虽有些偏于安全,但基本是合理的。 相似文献
34.
Kirsten Simonsen 《Geoforum》2004,35(5):525-528
This intervention address some of the social and epistemological mechanisms that construct an `international' writing space imbued with an Anglo-American hegemony. This is done by way of three examples, each making it possible to infer one of the general mechanisms at work. Taking off from the, comment, by the way of examples from Denmark, tries to illustrate how a truthful acknowledgement of the contextuality of geographical knowledges can multiply the spaces of critical geography--in the end enriching Anglo-American and non-Anglo-American debates alike. 相似文献
35.
An attenuation relationship based on Turkish strong motion data and iso-acceleration map of Turkey 总被引:2,自引:0,他引:2
This paper presents an attenuation relationship of peak ground acceleration (PGA) derived from Turkish strong motion data for rock, soil and soft soil sites and an iso-acceleration map of Turkey based on this relationship. For the purpose, among all the three-component accessible records, 221 records from 122 earthquakes that occurred in Turkey between 1976 and November 2003 were selected. The database was compiled for earthquakes with moment magnitudes (Mw) and PGA values ranging between 4.1 and 7.5, and 20 and 806 gal, and distances to epicenter considered in the database were between 5 and 100 km. From the regression analysis of the data, an attenuation equation of PGA considering rock, soil and soft soil conditions was developed. The PGA values predicted from the equation suggested in this study and those both from a few domestic equations and some imported equations were compared. In addition, an iso-acceleration map of Turkey was constructed using the suggested attenuation equation and considering both known active faults and epicenter locations of the earthquakes that have occurred in Turkey. 相似文献
36.
Total electron content (TEC) and foF2 ionosonde data obtained at Tucumán (26.9°S; 65.4°W) from April 1982 to March 1983 (high solar activity period) are analyzed to show the seasonal variation of TEC, NmF2 (proportional to square of foF2) and the equivalent slab thickness EST. Bimonthly averages of the monthly median for January–February, April–May, July–August and October–November have been considered to represent summer, autumn, winter and spring seasons, respectively. The results show that the higher values of TEC and maximum electron density of F2-layer NmF2 are observed during the equinoxes (semiannual anomaly). During daytime, both in TEC and in NmF2 the seasonal or winter anomaly can be seen. At nighttime, this effect is not observed. Also, the observed NmF2 values are used to check the validity of International Reference Ionosphere (IRI) to predict the seasonal variability of this parameter. In general, it is found that averaged monthly medians (obtained with the IRI model) overestimate averaged monthly median data for some hours of the day and underestimate for the other hours. 相似文献
37.
Introduction The acceleration response spectrum and peak ground acceleration are the necessary and im-portant parameters in earthquake-resistant design at present. They are still active research field. With the increase of digital high accurate strong motion observation data, especially the earth-quakes of Loma Prieta (M=7.0) in 1989; Landers (M=7.3) in 1992; Big Bear (M=6.4) in 1994 and Northridge (M=6.7) in 1994 in USA; Kozani (M=6.6) earthquake and afteshocks in 1995 in Greece; Dinar… 相似文献
38.
39.
Juanita Sundberg 《Geoforum》2005,36(1):17-28
This paper argues that critical geographies of Latin America begin with an analysis of how and why the bodies and geographies of geographers themselves matter. To focus on the geographer as a producer of knowledge is not to advocate the kind of navel gazing so abhorrent to many scholars. Rather, it is an effort to call attention to and critically assess how the geographer's embodied social position and geographic location inform the production of knowledge about and representations of Latin American people and nature. To illustrate how and why bodies and geographies matter, I draw from feminist and post-colonial theory and include examples from my own experiences and those of other researchers doing fieldwork in Latin American countries. I conclude by exploring the notion of situated knowledge as a tactic that writes bodies and geographies into academic texts. Ultimately, situating knowledge represents a political intervention and contribution to the broader goals of emancipatory politics shared by critical human geographers. 相似文献
40.
重要矿产资源尤其是战略性矿产的安全保障历来是世界各国关注的重点之一。关于战略性矿产的研究,欧美等发达国家和地区已经建立了一套比较成熟的理论和方法,并不定期更新战略性矿产目录。而我国对于战略性矿产的研究相对较晚,尚未形成统一的内涵意义、评价体系和方法。为此,本文在重新界定战略性矿产内涵基础上构建供应风险-经济价值二维评价体系,运用定性和定量相结合的评价方法综合评价我国主要矿产资源的战略性。 相似文献