SILTATION RATE IN A TRENCH DREDGED ON FLOODPLAIN IN ESTUARY     

FAN Jiahua Prof.  Senior Engineer  Inst. Water Conservancy  Hydroelectric Power Research  P.O. Box  Beijing  China 《国际泥沙研究》1993,(3)

I. INTRODUCTIONA discharge of 100--200 m3 / s is needed to be diverted from a tidal reach and utilized as cooling water for a Droposed power plant in the Yangtze Estuary. The diversionchannel is divided into two parts by a levee along the river bank, an open channel stretchinside the levee is connected with a trench dredged on the floodplain, as shown in Pig. 1.Since the flow and sediment regimes in these two stretches are different, analysis is madeseparately for each of them.11. ESTI…  相似文献   

Use of Analog Model to Predict Streamflow Depletion, Big and Little Blue River Basin, Nebraska by P. A. Emery-October, 1966     

Thomas A. Prickett  Associate Engineer   《Ground water》1967,5(1):55-56

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Hydration, ¹⁸O enrichment and oxidation during ocean floor hydrothermal metamorphism of ophiolitic metabasic rocks from E. Liguria,Italy     

E.T.C. Spooner  R.D. Beckinsale  P.C. England  A. Senior 《Geochimica et cosmochimica acta》1977,41(7):857-871

During ocean-floor hydrothermal metamorphism of a 225 m thick allochthonous Jurassic sequence of ophiolitic pillow lavas and underlying material in E. Liguria, Italy, the rocks were hydrated, enriched in ¹⁸O and oxidised. H₂O⁺ contents increased from ~0.3 to 3.8 wt.%, δ¹⁸O values increased from ~ +6‰ to values as high as +13.2‰, and ($\text{Fe}{}_2\text{O}{}_3\text{FeO}$1) increased from 0.18 to ratios as high as 1.0. Both δ¹⁸O values and oxidation ratios decrease in the original direction of increasing depth. Pillow margins are consistently more enriched in ¹⁸O and are more oxidised than cores.These observations are qualitatively interpreted in terms of a non-isothermal, heterogeneous reaction model of interaction of basalt with oxygen-bearing sea water during flow through the packed bed of pillows. Fluid flow approximated undirectional downward motion, and occurred in the recharge part of a cycle of single pass convection. Mass transfer through the pile was by flow (infiltration metasomatism), whereas intra-pillow mass transfer was diffusional. Oxygen isotope exchange and oxidation did not occur under conditions of perfect incremental equilibrium. An integrated bulk volumetric water/rock ratio of ~2 × 10³:1 is estimated from the oxidation profile.  相似文献   

Very large landslides in the Himalayas     

Senior Lecturer  TONY WALTHAM 《Geology Today》1996,12(5):181-185

Landslides are a major component of geomorphological processes on the steep slopes of the Himalayan mountains. Three slides in the Annapurna region demonstrate a sequence from large to very large failures.  相似文献   

Deriving the unitgraph without using rainfall data     

R. J. De Laine  Senior Lecturer 《Journal of Hydrology》1970,10(4):379-390

The characteristic of a linear time invariant system can be found uniquely from any two outputs that have no error: it is not necessary to know the inputs or the time duration of the system response. In hydrologic terms, the unitgraph of a catchment with linear characteristics may be found from records of runoff vs time.  相似文献   

Estimating overland flow erosion capacity using unit stream power   总被引：2，自引：0，他引：2  

Hui-Ming SHIH  Chih Ted YANG 《国际泥沙研究》2009,24(1):46-62

Soil erosion caused by water flow is a complex problem. Both empirical and physically based approaches were used for the estimation of surface erosion rates. Their applications are mainly limited to experimental areas or laboratory studies. The maximum sediment concentration overland flow can carry is not considered in most of the existing surface erosion models. The lack of erosion capacity limitation may cause over estimations of sediment concentration. A correlation analysis is used in this study to determine significant factors that impact surface erosion capacity. The result shows that the unit stream power is the most dominant factor for overland flow erosion which is consistent with experimental data. A bounded regression formula is used to reflect the limits that sediment concentration cannot be less than zero nor greater than a maximum value. The coefficients used in the model are calibrated using published laboratory data. The computed results agree with laboratory data very well. A one dimensional overland flow diffusive wave model is used in conjunction with the developed soil erosion equation to simulate field experimental results. This study concludes that the non-linear regression method using unit stream power as the dominant factor performs well for estimating overland flow erosion capacity.  相似文献   

Non-linear density evolution from an improved spherical collapse model     

Sunu Engineer  Nissim Kanekar  T. Padmanabhan 《Monthly notices of the Royal Astronomical Society》2000,314(2):279-289

We investigate the evolution of non-linear density perturbations by taking into account the effects of deviations from spherical symmetry of a system. Starting from the standard spherical top hat model in which these effects are ignored, we introduce a physically motivated closure condition which specifies the dependence of the additional terms on the density contrast, δ . The modified equation can be used to model the behaviour of an overdense region over a sufficiently large range of δ . The key new idea is a Taylor series expansion in (1/ δ ) to model the non-linear epoch. We show that the modified equations quite generically lead to the formation of stable structures in which the gravitational collapse is halted at around the virial radius. The analysis also allows us to connect up the behaviour of individual overdense regions with the non-linear scaling relations satisfied by the two-point correlation function.  相似文献   

Dynamic Behaviour of a Caisson Quaywall Under Strong Earthquake     

LIU Hanlong  DAI Huichao  Susumu IAI Professor  Geotechnical Engineering Research Institute  Hohai University  Nanjing  China. Senior Engineer  China Yangtze Three Gorges Project Development Corporation  Yichang  China. Doctor  Port  Harbour Research Institute  Ministry of Transport  Nagase  Japan. 《中国海洋工程》1999,(1)

—Effective stress analysis is performed to evaluate the residual displacement of a caissonquaywall during 1994 Hokkaido-Toho-Oki Earthquake and 1993 Kushiro-Oki Earthquake.Theconstitutive model used in this study is a multiple shear mechanism type defined in strain space and cantake into account the effect of rotation of principal stress axis.The earthquake accelerations recorded atthe outcropping rock during the earthquake are used as input bedrock motion.The results of finite ele-ment analysis are in good agreement with the observed behaviour of the quaywall.The analysis also indi-cates that liquefaction and high excess pore water pressure have a significant effect on the deformation ofthe caisson.Soil improvement is speculated as the most reliable measures against liquefaction.The influ-ence of soil improvement and the reasonable improved area are discussed in the paper.  相似文献   

Application of Line Boundary Technique to 2D Tidal Current Simulation   总被引：1，自引：0，他引：1  

SONG Zhiyao XUE Hongchao YAN Yixin Doctor  Senior Engineer  College of Harbor Waterway  Coastal Engineering  Hohai University 《中国海洋工程》1999,(4)

To deal with the problems concerning the shore boundary,moving boundary and engineeringboundary which are encountered frequently in 2D tidal current simulation by the finite difference method,theconcept of line boundary is introduced and studied here,and then the line boundary technique in common useis proposed in this paper.Analysis of some calculation cases shows that this technique is practical,effective,and simple in 2D tidal current simulation involving different boundaries.  相似文献   

Mechanics of a Grip System of Three-Key-Board Hydraulic Tongs Developed for Offshore Oil Pipe Lines     

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