曲靖水城水库坝基膨胀土特性研究     

唐蕴 《工程地质学报》2001,9(4):389-392

在膨胀土地区构筑建筑物一直是岩土工程界探讨的热点, 尤其是在膨胀土地区修筑水库大坝更是水利工程中的难点, 为此, 本文结合水城水库实际工程, 对膨胀土的特性进行了系统试验研究。水城水库库区为一膨胀土地区, 拦河大坝为一心墙堆堆石坝, 最大坝高 5 9.2m。本项工作系统地进行了膨胀土的物理 -力学性质试验及分析, 尤其是膨胀率与干容重和含水量及外覆压力关系分析。得出了该地区膨胀土的膨胀性不仅与其自身矿物成分有着重要关系, 同时其是否表现为膨胀还取决于天然干容重的大小、含水量及外覆压力的大小, 并且得出了它们之间的相互关系规律。  相似文献   

Statistical theory of weak field thermoremanent magnetization in multidomain particle ensembles     

Karl Fabian 《Geophysical Journal International》2003,155(2):479-488

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岩石磁学与古地磁实验室简介   总被引：6，自引：6，他引：6  

朱日祥  黄宝春  潘永信  邓成龙 《地球物理学进展》2003,18(2):177-181

近年来，中国科学院地质与地球物理研究所岩石磁学与古地磁学实验室始终以实验、观测和理论“三位一体”的研究思路为宗旨，提出了以先进的硬件设备、完善的测试环境和创新的实验方法为依托体系的现代实验室建设理念，富有创意地发展了一些实验技术和实验方法，建立了国际水平的实验条件和实验能力．良好的研究环境和富有开拓的研究思路，吸引了包括欧美国家在内的国际知名学者来实验室开展合作研究．近年来每年都有一批实验数据在Nature，JGR(Journal of Geophysical Research)，EPSL(Earth P1anet Sciences Letter)和中国科学、地球物理学报等国内外学术期刊发表．该实验室已逐步成为岩石磁学与古地磁学领域国内外研究中心之一，大大地提升了我国在该领域研究的国际地位．  相似文献   

磁流变阻尼器的构造设计及其阻尼力性能的试验研究   总被引：21，自引：2，他引：21  

李忠献  吴林林  徐龙河  周云 《地震工程与工程振动》2003,23(1):128-132

本文根据磁流变液的材料特点和磁路设计原则，设计并制作了一个双出 杆的剪切阀式磁流阻尼器，在伺服试验机上对所设计制作的磁流变阻尼器的阻尼力性能进行了试验研究，并分析了影响阻尼力的各种因素。结果表明：所设计制作的磁流变阻尼器具有一定的剩磁，但剩磁对阻尼力可调系数的影响很小；所设计制作的磁流变阻尼器能够达到的最大阻尼力和阻尼力可调系数都很理想。由此得出结论，本文所设计制作的磁流变阻尼器具有卓越的阻尼性能，可在土木工程结构的半主动振动控制设计中加以推广和应用。  相似文献   

Preliminary Results of Magnetic Measurements on Stream-Sediments from Buenos Aires Province,Argentina     

Chaparro  M.A.E.  Bidegain  J.C.  Sinito  A.M.  Gogorza  C.S.G.  Jurado  S. 《Studia Geophysica et Geodaetica》2003,47(1):121-145

A wide urban area in the Northeast of Buenos Aires Province (Argentina) is exposed to anthropogenic influence, mainly due to industrial and urban activity. In this area two streams were chosen, Del Gato and El Pescado streams. They have similar characteristics, although the first one runs through the built-up area and the other one through a rural area; consequently, Del Gato stream has a higher input of pollutants (fluvial effluents, fly ashes, solid wastes, etc.) than El Pescado stream.Magnetic measurements and geochemical studies were carried out on five sediment cores taken out from both streams with the aim of establishing a link between concentration of ferrimagnetic materials and contents of heavy metals. In order to investigate concentration of magnetic carriers and its intrinsic features (present magnetic minerals and grain size distribution) several magnetic parameters were measured and relations between them were analyzed.The magnetic characteristics for both sites indicate the presence of magnetically soft minerals in both streams, predominantly in Del Gato stream and with the additional presence of relatively hard minerals in El Pescado stream. Besides, a higher concentration of secondary ferrimagnetic minerals was found in Del Gato stream than in El Pescado stream.Chemical studies show (in some cases) a high concentration of some heavy metals (lead, copper, zinc, nickel and iron) on the upper 22 cm. Magnetic parameters, especially anhysteric remanent magnetization and contents of some heavy metals, showed a very good correlation.  相似文献   

Some characteristics of geomagnetic reversals inferred from detailed volcanic records     

Jean-Pierre Valet  Emilio Herrero-Bervera 《Comptes Rendus Geoscience》2003,335(1):79-90

The transitional virtual geomagnetic poles (VGPs) of the five most detailed records lie within the longitudinal bands of America, western Europe and eastern Asia. This distribution does not support the hypothesis of a direct link with heterogeneities of the lower mantle underneath Americas and eastern Asia. A similar distribution of VGPs persists by adding less detailed records and show similarities with the distribution of maximum inclination anomalies predicted by time-averaged field models. However, the two databases are far too limited to infer any recurrence of non-dipole components during reversals. Clusters of VGPs are observed in most records at various geographical locations without preference for specific longitudes, which most likely result from intense volcanism during short time periods rather than from transitional dipolar states.  相似文献   

Evaluating magnetic lineations (AMS) in deformed rocks   总被引：3，自引：0，他引：3  

Josep M. Pars  Ben A. van der Pluijm 《Tectonophysics》2002,350(4):283-298

Magnetic lineation in rocks is given by a cluster of the principal axes of maximum susceptibility (K_max) of the Anisotropy of Magnetic Susceptibility (AMS) tensor. In deformed rocks, magnetic lineations are generally considered to be the result of either bedding and cleavage intersection or they parallel the tectonic extension direction in high strain zones. Our AMS determinations, based on a variety of samples that were taken from mudstones, slates and schists from the Pyrenees and Appalachians, show that strain is not the only factor controlling the development of magnetic lineation. We find that the development and extent to which the magnetic lineation parallels the tectonic extension direction depends on both the original AMS tensor, which in turn depends on the lithology, and the deformation intensity. Rocks having a weak pre-deformational fabric will develop magnetic lineations that more readily will track the tectonic extension.  相似文献   

A multi-proxy analysis of climate impacts on the recent development of subarctic Lake Saanajärvi in Finnish Lapland     

A. Korhola  S. Sorvari  M. Rautio  P.G. Appleby  J.A. Dearing  Y. Hu  N. Rose  A. Lami  N.G. Camerson 《Journal of Paleolimnology》2002,28(1):59-77

Responses to recent climatic changes in the sediment of subarctic Lake Saanajärvi in northwestern Finnish Lapland are studied by comparison of various biological and sedimentological proxies with the 200-year long climate record, specifically reconstructed for the site using a data-set of European-wide meteorological data. The multi-proxy evidence of simultaneously changing diatom, Cladocera, and chrysophyte assemblages along with the increased rates of organic matter accumulation and pigment concentrations suggest that the lake has undergone a distinct typological change starting from the turn of the 20th century. This change, indicating an increase in lake productivity, parallels a pronounced rise in the meteorologically reconstructed mean annual and summer temperatures in the region between ca. 1850 and 1930's. We postulate that, during the Little Ice Age, the lake was not, or was only weakly, thermally stratified during summer, whereas the subsequent increase in air and hence epilimnetic water temperatures resulted in the development of the present summer stratification. The increased thermal stability of the lake created more suitable conditions for the growth of phyto- and zooplankton and changed the overall primary production from benthos to plankton. Mineral magnetic and carbonaceous particle records suggest long-distance pollution, particularly since the 1920's, yet the observed changes in lake biota and productivity can hardly be explained by this very minor background pollution; the 20th century species configurations are typical of neutral waters and do not indicate any response to pollution.  相似文献   

Magnetic hysteresis and rotational hysteresis properties of hydrothermally grown multidomain magnetite     

A. R. Muxworthy 《Geophysical Journal International》2002,149(3):805-814

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Magnetostratigraphic results from impact crater Lake El'gygytgyn, northeastern Siberia: a 300 kyr long high-resolution terrestrial palaeoclimatic record from the Arctic   总被引：4，自引：0，他引：4  

N. R. Nowaczyk  P. Minyuk  M. Melles  J. Brigham-Grette  O. Glushkova  M. Nolan  A. V. Lozhkin  T. V. Stetsenko  P. M. Andersen  S. L. Forman 《Geophysical Journal International》2002,150(1):109-126

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