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1.
地震作用下立式储液罐罐壁“象足”变形仿真分析 总被引：1，自引：0，他引：1
基于ANSYS软件建立了考虑液体晃动和罐底提离立式储液罐有限元模型,分别进行了水平地震和竖向地震作用下罐壁“象足”变形分析。分析表明:立式储液罐罐壁“象足”变形主要是由罐壁纵向压应力超过临界应力而产生的局部屈曲破坏,并非强度破坏。因罐底提离导致的罐底与基础反复撞击加大了作用在罐壁上的应力,使罐壁底部“象足”变形不断发展,最终导致罐壁撕裂。在完全相同地震加速度作用下,水平地震作用比竖向地震作用罐壁更早更容易进入屈曲状态,产生“象足”变形。 相似文献
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地震作用下立式储液罐罐壁"象足"变形仿真分析 总被引：2，自引：0，他引：2
基于ANSYS软件建立了考虑液体晃动和罐底提离立式储液罐有限元模型,分别进行了水平地震和竖向地震作用下罐壁"象足"变形分析.分析表明:立式储液罐罐壁"象足"变形主要是由罐壁纵向压应力超过临界应力而产生的局部屈曲破坏,并非强度破坏.因罐底提离导致的罐底与基础反复撞击加大了作用在罐壁上的应力,使罐壁底部"象足"变形不断发展,最终导致罐壁撕裂.在完全相同地震加速度作用下,水平地震作用比竖向地震作用罐壁更早更容易进入屈曲状态,产生"象足"变形. 相似文献
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位移谐波激励下拱顶锚固储罐的动力屈曲研究 总被引：1，自引：1，他引：0
地震下储罐罐壁发生屈曲是其主要的震害形式,研究储罐的动力屈曲特性尤为重要.以位移简谐波为水平激励,运用ADINA有限元软件对高径比分别为0.82、1.24和1.85的3种拱顶锚固储罐进行动力屈曲分析.根据Budiansky-Roth动力屈曲准则,通过谐波位移幅值对应的加速度峰值PGA和储罐位移响应,绘制特征节点的"伪平衡路径"轨迹,以确定临界加速度峰值,判断储罐动力屈曲.3种储罐模型在位移谐波激励下均为弹性屈曲.通过动力屈曲分析得出结论:储罐屈服的位置随高径比的不同有所不同,屈服多发生在径向变形最大处,罐壁内外面的塑性总应变值和屈服应力值大小不同等.最后以储罐模型B为例,将以"伪平衡路径"轨迹确定的临界应力与规范公式的计算结果进行了比较. 相似文献
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地震作用下大型储液罐的安全问题日益引起重视。基于ANSYS软件建立储罐液体耦合有限元模型,考虑罐底非线性接触效应,以El-Centro南北向和竖直向记录地震波为输入,研究水平激励以及水平和竖向同时激励两种工况下储罐的动力响应。研究结果表明,两种工况下靠近罐底1.2m处均发生了"象足"变形,竖向激励下水平相对位移增加了14%。竖向激励使得罐壁环向应力和轴向压应力均有不同程度的增加。竖向地震激励对液面的竖向晃动影响较小。储液罐底板在地震作用下发生了竖向提离和永久滑移,竖向激励时增长幅度均在10%左右。同时罐体基底剪力在竖向地震作用下也有所增大。储罐抗震设计时应考虑竖向地震分量的影响,研究结论可为立式储罐的抗震设计提供一定的参考和依据。 相似文献
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位移谐波激励下拱顶锚固储罐的动力响应分析 总被引：1，自引：1，他引：0
地震中拱顶锚固储罐的破坏将造成严重的后果,研究其地震作用下的动力响应特性具有一定工程意义。以位移简谐波为水平激励,运用AD INA有限元软件对一座3 000m3的拱顶锚固储罐模型进行动力数值模拟,系统分析了储罐内液面晃动波高、动水压力极值、罐壁应力、拱顶应力、拱顶位移等动力响应结果,将以位移谐波激励和以加速度谐波激励的储罐动力响应结果进行比较。分析表明,位移谐波激励下拱顶锚固储罐的液面晃动波高受场地影响较大;储罐应力分布具有一定规律性;采用位移谐波激励时其应力、位移和动水压力等较采用加速度谐波激励时大,液体晃动波高较小。 相似文献
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基于概率估计方法的立式储罐地震易损性研究 总被引：1，自引：1，他引：0
结合储罐的震害资料和震害特点,提出了基于概率估计方法的立式储罐地震易损性研究.考虑了结构的随机性及荷载作用的随机性,给出了各随机变量的概率分布模型及给定烈度下地震发生的概率.从可靠度指标的几何意义入手,提出了储罐的地震易损性计算方法.通过2×103m3和5×104m32种高矮罐的地震易损性研究,结果表明:通过概率方法和绘制地震易损性曲线的方式,更能直观的给出储罐各失效模式的地震易损性.储罐的地震易损性与地震烈度、高径比的关系很大,地震易损性随着地震烈度的增大逐渐增大;与2×103m3储罐相比,5×104m3储罐各失效模式地震易损性明显较小;从多种失效模式进行储罐地震易损性研究更具有科学性. 相似文献
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为了研究桩土、隔震层与罐体相互作用对15×104m3隔震储罐地震响应的影响,桩与隔震层采用弹簧-阻尼单元,罐体采用壳单元,流体采用势流体单元,基于ADINA建立数值仿真分析模型,在8度E1 Centro地震动激励下,应用Newmark数值积分方法进行地震响应分析.结果表明:隔震储罐基底剪力和基底弯矩相对于非隔震储罐明显降低,储罐罐壁加速度沿罐壁高度方向近乎平动,但对波高的控制效果不明显;除罐壁顶部外,动液压力明显降低;隔震后,罐壁有效应力和环向应力减震效应明显,对轴向应力和径向应力影响较小,建议从安全角度考虑,储罐非隔震设计时不考虑桩土作用,隔震设计时考虑桩土对罐体的影响. 相似文献
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《地震工程与工程振动》2015,(5)
立式浮顶储罐在强震作用下会发生罐壁屈曲、卡顶、浮顶下沉等震害。为降低储罐地震响应,以1 000 m3储罐为原型,按1:5的几何相似比设计缩尺模型,并以隔震周期为0.5 s进行并联隔震装置设计,给出其力学本构关系。采用模拟地震振动台试验方法,选取四种不同频谱特性的地震动对模型罐进行地震响应分析,结果表明:隔震层顶部加速度卓越频率有所降低,周期延长;隔震后储罐加速度、层间位移及动应力地震响应明显降低,但晃动波高有所放大;三向地震激励与单向地震激励相比,加速度地震响应明显放大,对晃动波高影响较小。建议储罐抗震减震设计时应考虑三向地震作用。 相似文献
9.
为考虑土与结构相互作用(SSI)对15×104m3大型立式储罐基础隔震效应的影响,采用弹簧-阻尼系统模拟地基土和隔震层,罐壁及底板采用壳单元,流体采用势流体单元,利用ADINA建立15×104m3储罐有限元模型,在峰值加速度0.2g El Centro波地震激励下,应用Newmark数值积分方法进行地震响应分析,结果表明:考虑SSI效应时,非隔震储罐的地震响应有所减小,而基础隔震时地震响应有放大效应。储罐抗震减震设计时,中软地基土上储罐从结构设计安全角度来说需要考虑土与结构的相互作用。 相似文献
10.
考虑SSI效应的立式储罐水平基础隔震研究 总被引：2，自引：0，他引：2
立式储罐在地震作用下破坏严重,损失较大.为了降低立式储罐在水平地震激励下的地震响应,考虑土与结构相互作用对储罐地震响应的影响,将立式储罐基础隔震体系简化为3质点5自由度力学模型.依据Hamilton原理建立立式储罐基础隔震体系的控制方程,给出了立式储罐基底剪力、倾覆弯矩、晃动波高和应力的理论表达.选取150000m3储罐,采用wilson-θ法对其进行了地震动响应分析.结果表明:储罐基础隔震体系能够降低储罐的地震响应;为获得理想的地震响应,场地、隔震周期和阻尼比存在优化取值区间;储罐抗震与减震设计要视设计安全需要来决定是否考虑土与结构的相互作用. 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
16.
《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
18.
Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
20.
K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献