共查询到20条相似文献，搜索用时 46 毫秒
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1问题的提出水工建筑物闸门提出水面运行时,通常有两种流态发生。当问下水位不影响其出流时,呈自由式堰流;当间下水位影响其泄量时,即为淹没式堰流。根据水力学理论,可知出流公式为：式中Q──泄流量（m／s）;B──水宽度（m）;hu──上游水头（m）;hl──下游水... 相似文献
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从水力学方程入手,对宽顶堰平板闸作了剖析,将孔流和堰流、淹没流与自由流作出了统一的解析模型,经原型实验检验,证明了成果的成因明确可靠,方法合理,可操作性强。 相似文献
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二河闸节制闸作为洪泽湖洪水出流的主要水利工程,在其控制运行中多次出现淹没式堰流流态,推求该水情条件下的流量一直采用的是连实测流量过程线法。为了能够更合理地掌握水工建筑物的出流规律,从而使流量推求更加精确,根据二河闸淹没式堰流流态下的历年实测流量资料,对其测验数据进行分析并率定出二河闸丰水期淹没式堰流的水位流量关系曲线。 相似文献
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单环入渗试验广泛应用于野外测定土壤水力参数。文章在三维非饱和带水分模拟程序VSF基础上,加入了单环入渗水流计算模块,并将改进的VSF与参数优化程序LEVMAR相耦合,构建了适用于单环入渗试验的土壤水力特征参数反演程序VSF-LEVMAR。利用大型室内土槽单环定水头入渗及变水头入渗试验资料,反求水平及垂向饱和入渗系数等土壤水力参数。应用结果表明:该方法既可以利用单环定水头入渗试验单独推求吸湿过程中的土壤水力参数,也可以结合单环定水头入渗与变水头入渗试验同时推求吸湿及脱湿过程中的土壤水力参数。 相似文献
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用流量资料推求上游水库未设水文站的梯级水库的设计洪水，一直没有一种较合理的方法。结合青岛市产芝水库防洪复核中采用上游水库报汛资料推求水库相应时段来水量，从而求得全流域来水量的做法，提出了一种推求梯级水库全流域来水量的新方法，可供类似地区参考借鉴。 相似文献
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为了计算瞬时溃坝最大流量,基于堰流与波流量相等原理,建立了瞬时溃坝最大流量与堰流关系,理论推导得到同一公式可以计算大坝全溃、横向局部溃坝、垂向局部溃坝及横垂向局部溃坝的瞬时最大流量的新通式,给出了该通式的基本和上限、下限及一般等通式。研究发现:瞬时溃坝流量与溃口堰坎类型有关,可以把瞬时溃坝最大流量、逐渐溃坝洪水或漫坝洪水的计算公式和相应系数统一到不同堰坎类型的堰流量计算中;而这些新通式相应系数的取值是被实验确认和经典著作肯定的,保证了系数取值的可靠和准确。这些新通式容易理解、形式简单、计算简便,参数取值可靠,把溃坝洪水计算的复杂问题转变为处理经典水力学的简单堰流计算。同时通过对比分析,充分论证了一般通式的合理性,并用国内外溃坝实例验证了计算方法和成果较科学、可靠、合理。 相似文献
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平底闸淹没孔流的水力计算或流量资料整编,由于影响因素复杂,加以闸下水位又不便直接观测,常以闸下游水位代替闸下水位,并以闸孔过水面积分析流量系数,或以自由式孔流的计算公式去分析淹没系数等,不但计算工 相似文献
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马斯京根模型参数估计方法探讨 总被引：13，自引：2，他引：13
以演算出流量与实测出流量的误差平方和最小为判据，直接推求了流量演进系数的最优估计值，而后反算参数ｘ，Ｋ，以适应于不同时段的流量演算。以实例证明了该法的可行性和较高的演算精度。 相似文献
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Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
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Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
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Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated. 相似文献
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位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。 相似文献
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某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。 相似文献
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摩擦桩基桩土间极限摩阻力取值问题探讨 总被引：1，自引：0，他引：1
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。 相似文献
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The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning. 相似文献
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The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time. 相似文献