新型组合连梁控制结构体系   总被引：9，自引：0，他引：9  

邓志恒  潘峰  陶晓光  唐光暹 《世界地震工程》2003,19(3):6-11

分析了连梁在水平力作用下的破坏机制，对连梁结构体系的发展及结构抗震控制进行了评述，在此基础上提出一种新型组合连梁控制结构体系，并对其进行了概念分析，提出了有待研究的若干关键问题。  相似文献   

博格达山晚石炭纪造山活动的变形地质记录   总被引：13，自引：2，他引：13  

王宗秀  李涛  周高志  卢苗安  柳永清  李寅 《地学前缘》2003,10(1):63-69

主要由钙碱性火山岩、火山碎屑岩组成的博格达古岛弧是天山缝合造山带的重要组成部分 ,是一个发育较成熟的山链 ,其演化经历了晚古生代的韧性剪切收缩 ;中生代伸展调整及新生代再造山过程。晚古生代的造山活动在博格达山有很好的地质记录 ,并以显著的韧性剪切变形带的形成和发育同造山的褶皱构造为特点。剪切变形带内同构造的石英脉中的锆石U PbSHRIMP测年结果与山链中花岗岩、辉长岩年龄颇为一致 (311～ 316Ma) ,这个年龄反映在结束洋盆散聚、碰撞焊接的晚华力西期造山过程中 ,博格达古岛弧内存在一次虽不甚强烈 ,但又较为明显的构造岩浆事件 ,其成因可能与引起石炭纪大规模裂陆式喷发的深部断裂构造重新活动有关。  相似文献   

河南省文峪金矿床构造控矿规律研究   总被引：6，自引：2，他引：6       下载免费PDF全文

徐叶兵  范永香 《地质与勘探》2003,39(5):30-34

峪金矿床是小秦岭金矿带内一大型金矿床，属韧—脆性叠加剪切带石英脉型金矿，构造是其首要控矿因素。早期韧性剪切带只对矿脉起宏观控制作用。晚期的脆性断裂为含金石英脉的直接控矿构造。成矿期脆性断裂的多次继承性活动分别控制了热液期4个成矿阶段。脆性断裂形成的空间形态对矿体形态产状具控制作用。有利的矿化富集部位为：①显示压扭性质的近东西向断裂沿走向产状变化处，沿倾向由陡变缓处，断裂面的凹凸转变处；②断裂分支复合部位；③成矿期断裂多次脉动的启张部位；④成矿期断裂构造继承性活动强的部位等。在构造控矿研究的基础上，结合前人部分研究成果。构建了该矿床构造控矿模式。  相似文献   

Estimation of fundamental periods of shear‐wall dominant building structures     

Can Balkaya  Erol Kalkan 《地震工程与结构动力学》2003,32(7):985-998

Shear‐wall dominant multistorey reinforced concrete structures, constructed by using a special tunnel form technique are commonly built in countries facing a substantial seismic risk, such as Chile, Japan, Italy and Turkey. In spite of their high resistance to earthquake excitations, current seismic code provisions including the Uniform Building Code (International Conference of Building Officials, Whittier, CA, 1997) and the Turkish Seismic Code (Specification for Structures to be Built in Disaster Areas, Ankara, Turkey, 1998) present limited information for their design criteria. In this study, consistency of equations in those seismic codes related to their dynamic properties are investigated and it is observed that the given empirical equations for prediction of fundamental periods of this specific type of structures yield inaccurate results. For that reason, a total of 80 different building configurations were analysed by using three‐dimensional finite‐element modelling and a set of new empirical equations was proposed. The results of the analyses demonstrate that given formulas including new parameters provide accurate predictions for the broad range of different architectural configurations, roof heights and shear‐wall distributions, and may be used as an efficient tool for the implicit design of these structures. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

韧性剪切带的变形变质与同构造熔融作用——以中祁连地块宝库河韧性走滑剪切带为例   总被引：5，自引：0，他引：5  

戚学祥  李海兵  张建新  蔡金郎 《地质论评》2003,49(4):413-421

宝库河韧性剪切带是发育在中祁连地块北缘上的一条向北陡倾,走向近东西,宽约6 km的右行平移型韧性剪切带.剪切带内岩石原岩为泥质岩、基性岩和花岗岩,变质程度达角闪岩相,变形变质温度在685～763±46℃之间,压力在0.62～0.83±0.13 GPa范围内.其内长英质条带非常发育,规模变化较大,分布局部相对集中且受剪切带控制,走向与剪切带一致,平行于叶理,孤立无根,并在后期递进变形过程中发生不同程度的糜棱岩化、布丁化和褶皱,主要成分为长石和石英,明显不同于韧性剪切前或后侵入的花岗岩脉或岩体.长英质条带特征、REE配分模式及剪切带内岩石的变形变质温度说明剪切带内发育的长英质条带与基体是同源的,是在剪切应变过程中剪切热使围岩内部分物质发生动态熔融形成的,是同构造熔融作用的产物.  相似文献   

Simulation and measurement of surface shear stress over isolated and closely spaced transverse dunes in a wind tunnel     

Ian J. Walker  William G. Nickling 《地球表面变化过程与地形》2003,28(10):1111-1124

Topographic interactions generate multidirectional and unsteady air?ow that limits the application of velocity pro?le approaches for estimating sediment transport over dunes. Results are presented from a series of wind tunnel simulations using Irwin‐type surface‐mounted pressure sensors to measure shear stress variability directly at the surface over both isolated and closely spaced sharp‐crested model dunes. Findings complement existing theories on secondary air?ow effects on stoss transport dynamics and provide new information on the in?uence of lee‐side air?ow patterns on dune morphodynamics. For all speeds investigated, turbulent unsteadiness at the dune toe indicates a greater, more variable surface shear, despite a signi?cant drop in time‐averaged measurements of streamwise shear stress at this location. This effect is believed suf?cient to inhibit sediment deposition at the toe and may be responsible for documented intermittency in sand transport in the toe region. On the stoss slope, streamline compression and ?ow acceleration cause an increase in ?ow steadiness and shear stress to a maximum at the crest that is double that at the toe of the isolated dune and 60–70 per cent greater than at ?ow reattachment on the lower stoss of closely spaced dunes. Streamwise ?ow accelerations, rather than turbulence, have greater in?uence on stress generation on the stoss and this effect increases with stoss slope distance and with incident wind speed. Reversed ?ow within the separation cell generates signi?cant surface shear (30–40 per cent of maximum values) for both spacings. This supports ?eld studies that suggest reversed ?ow is competent enough to return sediment to the dune directly or in a de?ected direction. High variability in shear at reattachment indicates impact of a turbulent shear layer that, despite low values of time‐averaged streamwise stress in this region, would inhibit sediment accumulation. Downwind of reattachment, shear stress and ?ow steadiness increase within 6 h (h = dune height) of reattachment and approach upwind values by 25 h. A distance of at least 30 h is suggested for full boundary layer recovery, which is comparable to ?uvial estimates. The Irwin sensor used in this study provides a reliable means to measure skin friction force responsible for sand transport and its robust, simple, and cost‐effective design shows promise for validating these ?ndings in natural dune settings. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

党政机关电子政务建设的若干问题   总被引：1，自引：4，他引：1  

任锦华 《测绘科学》2003,28(1):12-16

以从事政务信息化建设的实践经验为基础 ,对电子政务建设的基本问题进行了系统分析 ,内容包括 :信息关系和信息控制、信息分类、数据库结构、软件系统开发思路、电子政务的工作目标、服务对象、服务模式、电子政务建设的技术措施等。  相似文献   

Jurassic Dextral and Cretaceous Sinistral Movements Along the Hida Marginal Belt     

Kazuhiro Tsukada 《Gondwana Research》2003,6(4):687-698

The Hida marginal belt (HMB), which consists of various kinds of fault-bound blocks, is located between the continental massif of the Hida belt and the Mesozoic accretionary complex of the Mino belt in Central Japan. Detailed field investigation reveals that the HMB had grown through the two different movements, i.e., Jurassic dextral and Cretaceous sinistral movements. The Jurassic dextral ductile shear zones run in the southern marginal part of the Hida belt and the northern part of the HMB, whereas the Cretaceous sinistral cataclastic shear zones occur in the southern part of the HMB and the northern marginal part of the Mino belt. Geologic map and field evidence seem to suggest that the Jurassic dextral movement form the fault-bound blocks of the HMB to form the basic structure of the Hida marginal belt, i.e., formation of the ‘proto-HMB.’ Following the dextral movement, the sinistral one restructured the ‘proto-HMB’ to complete the present feature of the Hida marginal belt. The Cretaceous sinistral movement might result in the sinistral collision between the proto-HMB and the Mino belt.  相似文献   

Recent Precipitation Trends in Hungary in the Context of Larger Scale Climatic Changes   总被引：1，自引：0，他引：1  

Domonkos  Peter 《Natural Hazards》2003,29(2):255-271

The time series of monthly precipitation totals from 14 Hungarian observing stations (1901–1998) were analysed to reveal the long term changes in precipitation characteristics occurred in the 20th century. A particular attention was given to the changes in the recent decades and their links with the larger scale climatic and circulation changes over Europe and the Atlantic.The statistical significancesof systematic changes are controlled by linear trend analysis and the Mann–Kendall test. The long term fluctuations are illustrated applying a 15-point Gaussian filter on the time series. The Standardised Precipitation Index is used to evaluate the changes in the drought event frequency. The relationships with larger scale changes are mostly discussed relying on contemporary papers, and the Grosswetterlagen Catalogue is used as well.The annual precipitation total decreased by 15–20% in Hungary during the 20th century. The decline is substantial in both halves of the century, but the precipitation sums in the transition seasons declined in the first 50 years, and the winter precipitation decreased in the latest decades. The precipitation total of the period November–February declined significantly in the last 50 years. In the same time the mean winter value of the North Atlantic Oscillation Index (NAOI) increased, the positions of the main pressure patterns over the Atlantic are shifted northeastward, and lot of other coherent changes detected in the winter climate of the European–Atlantic region. The mean summer precipitation total has hardly changed, but the frequency of summer drought events increased. There are some signs of a shift of the Hungarian summer climate towards a Mediterranean like climate.  相似文献   

Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey   总被引：1，自引：0，他引：1  

J. L. Régnier  U. Ring  C. W. Passchier  K. Gessner  T. Güngör 《Journal of Metamorphic Geology》2003,21(7):699-721

Abstract P–T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid‐crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Çine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Çine nappe underneath the Selimiye shear zone record maximum P–T conditions of about 7 kbar and >550 °C. Metasedimentary rocks from the overlying Selimiye nappe have maximum P–T conditions of 4 kbar and c. 525 °C near the base of the nappe. Kinematic indicators in both nappes are related to movement on the Selimiye shear zone and consistently show a top‐S shear sense. Metamorphic grade in the Selimiye nappe decreases structurally upwards as indicated by mineral isograds defining the garnet‐chlorite zone at the base, the chloritoid‐biotite zone and the biotite‐chlorite zone at the top of the nappe. The mineral isograds in the Selimiye nappe run parallel to the regional S_R foliation, parallel the Selimiye shear zone and indicate that the Selimiye shear zone formed during this prograde greenschist to lower amphibolite facies metamorphic event but remained active after the peak of metamorphism. ⁴⁰Ar/³⁹Ar mica ages and the tectonometamorphic relationship with the Eocene Cyclades–Menderes thrust, which occurs above the Selimiye nappe in the study area, suggests an Eocene age of metamorphism in the Selimiye nappe. Metasedimentary rocks of the Çine nappe 20–30 km north of the Selimiye shear zone record maximum P–T conditions of 8–11 kbar and 600–650 °C. An age of about 550 Ma is indicated for amphibolite facies metamorphism and associated top‐N shear in the orthogneiss of the Çine nappe. Our study shows that simple monophase tectonometamorphic fabrics do not always indicate a simple orogenic development of a nappe stack. Preservation in some areas and complete overprinting of those fabrics in other areas apparently occur very heterogeneously.  相似文献