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YU Wei-Sheng Post-Doctoral Fellow Hydraulic Research Laboratory National Taiwan University Taipei Taiwan China LEE Hong-Yuan Professor Department of Civil Engineering National Taiwan University Taipei Taiwan China 《国际泥沙研究》1993,(2)
I. INTRODUCTIONWhen a sediment--laden flow reaches the backwater zone of a reservoir, the suddenreduction of flow velocity causes sediment particles to settle toward the river bed. Undercertain circumstsnces, it will plunge and form a layer of sediment--water mixture flowingbeneath the water surface. This flowing layer is called the turbidity current. A turbiditycurrent is relatively stable and has important impacts on reservoir sedimentation.In the case of deep reservoirs, due to temper… 相似文献
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A rectangular flume with dimensions of length 180 cm, height 60 cm and width 20 cm was used to observe the entry angle (i.e. angle between the interface and the centerline of the slot) of a two-layer flow withdrawal by a line sink. Saline water was used to form a bottom density current and red dye was applied. Based on the experimental data, one could see that the dimensionless discharge is more influential on the entry angle than the depth-averaged concentration of the lower-layer flow. Thus, the influence of concentration on experimental conditions is negligible for evaluation of the entry angle. The absolute values of entry angles increase with the absolute values of the dimensionless discharge. Almost all absolute values of the theoretical angle are bigger than that of the measured angle with a deviation bounded within 0.15 rad. The influence on the entry angle from the dimensionless discharge is symmetrical between the drawdown curve (interface above the slot) and the suck-up curve (interface below the slot). This phenomenon can be seen from a simplified form of a theoretical formula. 相似文献
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ZHAO Junyou GUO Aiju DING Keqin LIU Chuntu
Lecturer Petroleum University of China Shangdong P. R. China.
Engineer Zhongyuan Petrochemical Corporation Henan P. R. China.
Postdoctoral Fellow 《中国海洋工程》1999,(1)
-This paper carries out the analysis of mechanics of a grip system of three-key-board hydraulictongs developed for offshore oil pipe lines which has been successfully used in oil fields in China.The mainimprovement of this system is that a lever frame structure is used in the structural design,which reducesgreatly the stresses of the major components of the oil pipe tongs.Theoretical analysis and numerical calcu-lation based on thirteen basic equations developed show that the teeth board of the tongs is not easy to slipas frequently happens to other systems and is of higher reliability. 相似文献
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CHEN Li Assoc.Prof.Wuhan University of Hydraulic Electric engneering China LIU Qingquan Assoc.Research Fellow. Institute of Mechanics of Chinese Academy of Sciences Beijing China ZHANG Shuofu Senior Eingeer. Department of Water Conservancy Pow 《国际泥沙研究》1997,(3)
LINTRODUCTIONTheturbulenceoftheflowvelocityisresultedfromthecombinationofinnerinstabilityoftheflowandouterdisturbance.Int1Vo-dimensionalsteadyuniformflowasac7eknow.nomattersedimentconcentrationis0ingeneralorveryhigh.TheverticaldistributionofturbulentintensityoflongitudinalvelocityQhasasimilartendenc}'fohasaminimumatthesurface,thenincreasesinpacewiththedecreasingofthedistancefromthebedy,atsomewherenearthebed.Itreachesamaalmtlm(forhyperconcentratedflowwithaflowcoreinwhichvelocitygradientdu… 相似文献
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西淋岗第四系断层探测及活动性评价 总被引：1，自引：0，他引：1
利用地质雷达、氡气测量和释光测年方法对珠江三角洲北部西淋岗断裂进行探测并界定了地层年龄。结果表明：在晚更新世期间,西淋岗地区发生了至少2次突发性断裂活动。第一次活动在距今4万a左右,断层上盘地块发生了较大幅度的单边倾倒,造成断层两盘产生了近55 m的断距,形成了第四系内的角度不整合接触;在距今2万a之后,断裂第二次活动,形成了地表所见到的053 m地层错动。此外,断裂上方土壤氡气异常峰值大于背景值3倍,这说明了西淋岗断裂具有活动性和潜在危险性,也改变了珠三角地区断裂为“蠕滑断裂”的认识。 相似文献
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Onyx W. H. WAI 《国际泥沙研究》2009,24(4):425-438
The so-called fine sediment in many coastal areas and estuaries in China is mostly referred to the mixture of cohesive sediment and non-cohesive sediment. To predict the mixed type time sediment transport, sediment carrying capacity formulae combined with the 2-D suspended sediment transport equation and morphologic equation have been widely used in China. In the present study, the sediment carrying capacity formula suggested by Dou et al. （1995） for wave conditions has been improved and implemented for the prediction of sediment transport in nearshore regions where wave activities are significant. The improvement is based on the wave energy dissipation principle inside and outside the surf zone. In the improved formula, sediment in suspension increases with the magnitude of the wave period and this feature complies with general observations. More than 300 laboratory and field measured data sets have been reviewed and 12 of them have been used to verify and determine the major coefficients in the improved formula. The application of the sediment carrying capacity model in combined wave and current situations shows that the model can faithfully reproduce the cross-shore sediment concentration distributions at the southwest coast of Bohai Bay. 相似文献
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T.SONG Post-Doctoral Fellow School of Civil Structural Engineering Nanyang Technological University Nanyang Avenue Singapore . Presently Civil Engineer Engineering Depatment Technology Division Maritime Port Authority of Singapore. 《国际泥沙研究》1997,(3)
I.INTRODUCTIONBedloadtransportinsteadyuniformopenchannelflowhasbeenextensiVelystudied.Manyoftheformulasdevelopedforthepredictionofbedloadtransportinuniformopen-channelflowcanbebroughtinthefollowingform(ChienandWan,1983);ac=f(O)(l)xvhereacisthedimensionlessparameterofbedloadtranSPortandOisthedimensionlessparameterofflowintensity.TheseparametersaredefinedasfwheregsisthebedloadtranspoftratePerunitwidthindryweight;disthesedimentdiameter,Sisthebedslopeofthechannel;Rbisthehydraulicradiusdue… 相似文献
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Suspended load in flows on erodible bed 总被引：1，自引：0，他引：1
Steady state suspended-load of sediment transported in flow over erodible beds usually is treated by the advection-diffusion approach, though in recent years, it is being treated as a two-phase flow phenomenon incorporating kinetics of sediment particles. Among the advection-diffusion approaches, Rouse＇s equation is the well-known, although a number of researchers in later periods have attempted to improve it by modifying the mixing length concept taking into account other aspects. In this paper, the advection-diffusion approach and associated logarithmic law of flow velocity are revisited. It is concluded from the logarithmic law that the Reynolds shear stress is a linear function of height above the bed, which reduces to bed shear stress in the case of a long horizontal channel. As a consequence, it is shown that the volumetric concentration of sediment is best approximated by the sum of two power laws of height above the bed. An equation is derived for the suspended-load transport rate in terms of elementary functions. 相似文献