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361.
钢管高性能混凝土压弯构件滞回性能试验研究 总被引:2,自引:1,他引:2
考虑钢材强度、混凝土强度、轴压比等参数,进行了18个钢管高性能混凝土试件的试验,分析在往复荷载作用下钢管高性能混凝土荷载-位移关系曲线的特点、构件的轴向变形和抗弯刚度退化情况,并初步探讨往复荷载作用下的钢管高性能混凝土压弯构件承载力。 相似文献
362.
Introduction To correctly understand the tectonic deformation of continental lithosphere, its dynamical mechanics and seismic activity, we should firstly acquire the velocity field and strain field of lithospheric tectonic motion with fine resolution and consistent accuracy (Molnar and Lyon-Caen, 1989; Molnar, 1990). And the quality, distribution and density of observed data are the basis for studying crustal tectonic deformation. In the past, crustal deformation is usually determined indi-r… 相似文献
363.
本文首先对ENSO与中国东部地区夏季逐月(6~8月)降水的年际关系进行了分析,结果表明NINO3区夏季海温与东部地区8月降水在整个年代尺度上改变显著,1974年以前的年际相关关系比1974年后显著,且1974年前后发生了年际相关型的改变.其次,1974年以前和1974年以后环流形势发生了明显变化. 相似文献
364.
JointsolutionoflevelingandgravitydataincrustaldeformationmonitoringZUSHENGZHANG1)(张祖胜)YUANXIYANG2)(杨元喜)HANRONGSUN1)(孙汉荣)Z... 相似文献
365.
A preliminary research establishing the present-time intraplate blocks movement model on the Chinese mainland based on GPS data 总被引:4,自引:0,他引:4
Shuo-Yu Zhou Yue-Gang Zhang Guo-Yu Ding Yun Wu Xiao-Jun Qin Shun-Ying Shi Qi Wang Xin-Zhao You Xue-Jun Qiao Ping Shuai Gan-Jin Deng 《地震学报(英文版)》1998,11(4):403-412
The Chinese mainland is regarded as the best area for studying the continental crustal movement and dynamics. In the past,
based on the ground surface observation, it was very difficult to study the movement of the intraplate blocks within a range
of larger space and a time scale of several years quantitatively. In this paper, a method of calculating the Euler vectors
of present-time motion among blocks by using Cardan angles has been given completely based on two periods of GPS repetition
measurement data of the National Ascending Plan of China (NAPC) — the study and application of current crustal movement and
geodynamics in 1994 and 1996. A present-time blocks movement model on the Chinese mainland (PBMC-1), which describes the motion
of seven blocks—Tibet, Chuan-Dian, Gan-Qing, Xinjiang, South China, North China and Heilongjiang block, is established preliminarily.
The velocity field of the relative motion among the intraplate blocks and boundary motion in the Chinese mainland are firstly
given within several years time scale. It is shown by the results calculated with the model that the velocity-rate of each
block is reduced gradually from the south to north and from the west to east, and the motion direction changes gradually from
NNE to E, even SEE or SE. The collision of Indian plate plays a leading role in the movement of the intraplate blocks in the
Chinese mainland, while the motion manner and velocity-rate of block boundary zone (fracture zone) depend on the motion of
every block again. The present-time motion of a time scale of several years computed with the model is not only largely consistent
with the average motion of a time scale of several million years derived from geology, but also very coincident with the results
of geophysical and astronomic observation. It is shown preliminarily that the observed results of space geodesy techniques
such as GPS etc. are capable of discovering the crustal movement at present.
This study is supported by the National Natural Science Foundation of China (NNSFC), National Ascending Plan of China (NAPC)
and Chinese Joint Seismological Science Foundation (CJSSF). 相似文献
366.
The classical solution to the bearing capacity problem predicts the limit load on symmetrically loaded shallow strip footings. A useful hypothesis was suggested by Meyerhof to account for eccentricity of loading, in which the footing width is reduced by twice-the-eccentricity to its ‘effective’ size. This hypothesis sometimes has been criticized as being overconservative. This paper examines Meyerhof’s suggestion and presents the bearing capacity of eccentrically loaded footings calculated using the kinematic approach of limit analysis. It is found that the effective width rule yields a bearing capacity equivalent to that calculated based on the assumption that the footing is smooth. For more realistic footing models and for cohesive soils the effective width rule is a reasonable account of eccentricity in bearing capacity calculations. Only for significant bonding at the soil-footing interface and for large eccentricities does the effective width rule become overly conservative. For cohesionless soils, however, the effective width rule may overestimate the best upper bound. This overestimation increases with an increase in eccentricity. © 相似文献
367.
Genetic types of diamond mineralization 总被引:1,自引:0,他引:1
A. A. Marakushev Sang Longkang You Zhendong I. A. Zotov N. N. Pertsev N. A. Paneyakh 《中国地球化学学报》1998,17(1):12-28
The paper describes the proposed models of diamond formation both in meteorites and in kimberlite and lamproite bodies, metamorphic
complexes and explosive-ring structures (“astroblemes”). The diamond distribution in meteorites (chondrites, iron meteorites
and ureilites) is restricted to taenite-kamasite phase. The diamond generation here is tied up with the first stage of evolution
of the planets. This stage is characterized by high pressure of hydrogen, leading to the formation of the planet envelope.
The second stage of planet evolution began with the progressive impoverishment of their atmospheres in hydrogen due to its
predominant emission into the space and to progressive development of oxidative conditions. The model appears to have proved
the relict nature of diamond mineralization in meteorites.
Diamond and other high-pressure minerals (its “satellites”) were crystallized without any exception in the early intratelluric
stages of peridotite and eclogite-pyroxenite magma evolution just before the magma intrusion into the higher levels of the
mantle and crust where diamond is not thermodynamically stable. The ultramafic intrusive bodies (bearing rich relict diamonds)
in the base of a platform appear to be the substrata for the formation of kimberlite-lamproite magma chambers as a result
of magmatic replacement. The model explains the polyfacial nature of diamondiferous eclogites, pyroxenites and peridotites
and discusses the process of inheritance of their diamond mineralization by kimberlites and lamproites.
Diamond productivity of metamorphic complexes is originated by the inheritance of their diamonds from the above-mentioned
primary diamondiferous rocks. Large diamondiferous explosive-ring structures were formed by high-energy endogenic explosions
of fluid which came from the Earth’s core. This high energy differs endogenic impactogenesis from explosive volcanism. It
proceeds at very high temperature to create diaplectic glasses (monomineral pseudomorphs) —the product of isochoric melting,
at the pressure high enough for the stable formation of very high-density minerals (coesite, stishovite, diamond, lonsdaleit,
and chaoite).
The research project was financially supported by the Russian Foundation of Fundamental Sciences (93-05-8566, 96-05-64307,
and 96-05-00026c0) and China National Natural Science Foundation (No.49794041, No.49611121831). 相似文献
368.
369.
超高压变质岩的全球分布与地球演化节律 总被引:4,自引:0,他引:4
高压、超高压变质作用不是一个局部的孤立的地质现象,而是一个时空跨度大、范围广、影响构造观的重要科学问题。文中讨论了世界上三类(13个)典型超高压变质地区的地质学岩石学特点,从全球构造的角度研讨了超高压变质的时空分布,从而得到下列认识:(1)所有高压、超高压变质岩均分布于全球活动带及其次级褶皱带内,超高压变质岩常常保存于多期变质和变形的基底片麻岩块体中,与深位壳型剪切带关系密切。(2)现有的年代学资料说明大部分超高压变质带出现于显生宙不同时代的褶皱带(造山带)内。(3)超高压变质演化的多阶段性,说明了地球从收缩到膨胀的节律现象。(4)从欧亚大陆范围看来,从北而南,从陆到洋超高压变质有逐渐变新的趋势,可能说明欧亚大陆从中生代以来,有从大陆向大洋方向增生的总趋势。 相似文献
370.
尤恩沛 《吉林大学学报(地球科学版)》1987,(3)
本文对砂金矿床储量计算现存的某些问题提出了自己的看法,指出了由于不正确的计算方法给采金船生产带来的某些危害。着重论述了正确运用混合砂品位指标在矿床储量计算中的意义;单项钻孔工程混合砂品位表示方法、原则与采金船设计、生产的关系;关于矿体圈定中某些问题的处理。 相似文献