EXPERIMENTAL STUDY ON BED SHEAR STRESS AND SEDIMENT TRANSPORT IN A MEANDERING LABORATORY CHANNEL

1 INTRODUCTION River erosion is a complex phenomenon. The rate of bank retreat is determined by flow, bed topography, sediment transport, bank properties, and water quality. Prediction of future river planform changes and the knowledge of river erosion and river meandering are required for land use planning in alluvial river valleys and determining locations for bridges and hydraulic structures. The control of riverbank erosion requires prediction of flow and bed features in a meanderin…     

EXPERIMENTAL STUDY ON DAM-BREAK FLOOD WAVES OVER MOVABLE BED CHANNEL

1 INTRODUCTION During the last century, the propagation of dam-break flood waves has been the object of intense scientific and technical activity. The topic was initially approached by finding analytical solutions for the shallow-water equations in schematic situations featuring fixed bed and nil flow resistance. An example of this approach can be found in Stoker (1957). The vertiginous increase of automatic calculus which occurred during the last few decades has made it possible to ach…     

EXPERIMENTAL STUDY ON SEDIMENT DISTRIBUTION AT CHANNEL BIFURCATION

1 INTRODUCTION Bifurcations are typical features in alluvial rivers as well as in estuaries. In braided rivers confluence and bifurcation occur regularly (Fig.1). A bifurcation occurs when a river splits into two branches (Fig. 2). This happens when a middle bar forms in a channel or a distributary carries flow from the main river. In estuaries when the direction of tidal flow turns around an island, a confluence becomes bifurcation and vice versa. A braided river in the upstream end o…     

AN EXPERIMENTAL STUDY ON BEDMAKING AND CATASTROPHIC PROCESSES IN ISLAND BRAIDED CHANNEL

LINTRODUCTIONAstudyonevolutionandpredictionofthefluvialgeomorphicsystemhasdevelopedinthe1970's(Scheideggef,1975),andisstillapplied.Fromthemiddleofthe1980'son,researchofcatastrophicprocessesinthefluvialgeomorphicSystem(catatrophism,hazards)hasbeenfocusedon(SchummandChorley,1983,ShenandSchumm,1981,Chorley,SchununandSugden,1985).WhenafluvialgeomorphicSystemislocatedatthelinearregionofanollequilibriumstatebutveryclosetoequilibriumone,theboundaryconditionprotectstheSystemfromequilibrium,an…     

EXPERIMENTAL STUDY ON THE RELATIONA OF BED MORPHOLOGY WITH SURFACE FLOW IN MEANDER CHANNELS

Alternate bars have the property that they migrate downstream whenever floods occur. However, in meander channels whose bend angles are larger than a critical value, the migration of bars can be suppressed, and the positions of bank erosion and flood attack also will be steady. In this study, the bed morphology in flume channels with bends of various lengths and angles is investigated at various flow discharges, and the relation of bed morphology to surface flow is investigated in detail using fluid measuring software. An effort is made to obtain guidelines for the plane shape design of meander channels. Based on the experimental results of bed topography and measurement of surface flow direction and velocity distribution, from the viewpoint of bank erosion and the concentration and dispersion of flood flow the most suitable plane shape for meandering channels is suggested through which the migration of alternate bars is suppressed.     

AN EXPERIMENTAL STUDY OF BED DEFORMATION IN UNSTEANY NON-UNIFORM FLOWS

ＡＮＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＹＯＦＢＥＤＤＥＦＯＲＭＡＴＩＯＮＩＮＵＮＳＴＥＡＮＹＮＯＮ－ＵＮＩＦＯＲＭＦＬＯＷＳ￥ＺｈａｏｙｉｎＷａｎｇ；ＷｏｌｆｇａｎｇＫｒｏｎ；ａｎｄＥｒｉｃｈＪ．ＰＩａｔｅ（Ｐｒｏｆ．Ｄｒ．ＳｅｎｉｏｒＥｎｇｉｎｅｅｒ...     

NUMERICAL SIMULATIONS OF SCOUR AND DEPOSITION IN A CHANNEL NETWORK

1 INTRODUCTION Evolution of the river bed in alluvial channels has been studied by many researchers using analytical and numerical approaches. The use of analytical approach alone is insufficient for solving natural river engineering problems. With rapid growth in computer technology, numerical models have become a popular means for the study of mobile bed hydraulics. During the past decade, several numerical models have been developed. Most of the computer codes, such as HEC2SR (Si…     

BED SHEAR IN EVOLVING SCOUR AT A CYLINDER:A THEORETICAL APPROACH

ＢＥＤＳＨＥＡＲＩＮＥＶＯＬＶＩＮＧＳＣＯＵＲＡＴＡＣＹＬＩＮＤＥＲ：ＡＴＨＥＯＲＥＴＩＣＡＬＡＰＰＲＯＡＣＨＳｕｂｈａｓｉｓｈＤＥＹ１ａｎｄＳｒｉｊｉｂＫ．ＫＡＲ２Ａｂｓｔｒａｃｔ：Ｔｈｅｔｅｍｐｏｒａｌｖａｒｉａｔｉｏｎｏｆｓｈｅａｒｓｔｒｅｓｓ...     

EXPERIMENTAL STUDY ON SCOURING OF COHESIVE DEPOSITS IN SALT WATER

L BRieF DESCRIPTION OF MEmOD AND EXPERruENTAL CONDrrIONS OFSTUDESThe experimentS were conducted in a flume 17m long and 0.5m wide, the water depth being12 to 13cm. To keep from corrosion a drculahng system with 7.5 kw stainlys sac pump and.ic cm plashc pipe for delivering salt bater were adoptal. The sketCh of the experimental numeis shown in Fig. 1.In order to keep the flow current as close to uniform flow as possible, three different bottom slopes i.c. nat slope, i = o.2…     

EXPERIMENTAL STUDY ON SALTATION OF SOLID GRAINS IN FLOWING WATER

This paper deals with the saltation of bed-load solid grains in flowing water. Experiments have been carried out by means of high-speed photographing and advanced data processing techniques while the analysis is made by combined method of mechani- cal and statistical theories. Experiments reveal that saltation is the main form of the bed-load transport under ordinary flow conditions. Taking successive saltation as the model of bed-load transport, systematic analysis has been made with regard to the forces acting on grains and the variation of their magnitudes along the saltation trajec- tories to obtain the kinematic and dynamic properties of these grains. The statistical analysis shows that the probability density functions of the relative height and length of saltation are in conformity with distribution, while the probability density functions of the relative velocities of saltation are in conformity with the Gaussian distribution.     

EXPERIMENTAL STUDY ON FLOW AND SEDIMENT MOVEMENT IN CAVITY CIRCULATIONS

1 INTRODUCTION Cavity channels are often found in harbor basins, waterways approaching navigation locks, trench intakes and so on. Because of the expansion of channel section, the main flow is separated from the boundary and forms a circulation flow near the cavity crest. In general, the velocity and turbulent intensity in the circulation flow are lower than that in the main flow, as a result, sediment drawn into the cavity basin is very likely to be deposited there. For instance, the de…     

EXPERIMENTS ON FLOW AROUND A CYLINDER IN A SCOURED CRANNEL BED

1 INTRODUCTION'LOcal scour around a pier is a result of the interatiOn amongst the pier, the aPproach flow and theerodible bed. The Presence of a pier results in a stagnation pressure build-up in front of the pier and athree-dimensional tUrbulent flow echaracterized by the downward flow ahead of the pier and the so-called horseshoe vortex along the base of the Pier forms itself The flow modifies the erothe bed inthe vicinity of the pier when local scour takes place (Graf and AJhnakar l…     

EXPERIMENTAL STUDY ON DEFORMATION FABRICS OF QUARTZ AND CALCITE IN SHEAR ZONE

Frictional experiments of samples with quartz and calcite sandwich have been operated under certain confining pressures, strain rate and different temperatures. Samples deformed and undeformed have been studied by means of microscope, TEM, and U-Stage. On the basis of this, changes of deformation micro-structures and fabrics of quartz and calcite aggragates with temperatures under condition of simple shear have been analyzed     

EXPERIMENTAL AND FIELD STUDY ON MINING-PIT MIGRATION

1 INTRODUCTION Because of the large quantity of sand and gravel in their beds, rivers have always been considered as a major source of sand and gravel for civil works. Acceptable quality, ease of extraction and economy are some of the reasons could be mentioned. Unfortunately, specific laws and regulations regarding the safe in-stream mining have not been provided for users and officials. What should be taken into account are the effects of over-mining of sand and gravel, which can cause …     

IMPACTS OF DIMENSION AND SLOPE OF SUBMERGED SPUR DIKES ON LOCAL SCOUR PROCESSES - AN EXPERIMENTAL STUDY

1 INTRODUCTION In alluvial streams bed scour often occurs if the sediment load is less than the transport capacity of the flow. Two types of scour are identified, namely local scour and channel bed scour. Channel bed scour can be further classified accord…     

EXPERIMENTAL STUDY ON WAVE ENERGY DISSIPATION AND COHESIVE SEDIMENT TRANSPORT IN SILT COAST

EmmmL STonY ON w^rs EareGY DlsSunnox AunCOIIES1VE SEDonT TRANSPORT 1N SirT COASTShaong HUl and Onyx WAI2Abstract:The interahon betwee the wave and fluld mud laye Plays an twrtan fOle in the develOPmen ofsilt coast. Sediment is essenhally transported in the form of rheological flow of mud laye unds thewave achon, and on the other hand, the fluid Inud layer dams the wave consfory. ms papestUdies the laws of wave energy dissiPation and mud bed deformhon, and the moveInen of…     

EXPERIMENTAL STUDY ON SEDIMENTATION IN EXCAVATED TRENCH UNDER THE ACTION OF TIDAL FLOW

INTRODUCTIONThe planned outer ring road in Shanghai City crosses the Huangpu mver, a tribuop of the YangtzeXiver Veq near the river mouth. The sinldng method is reconunended in constIUchon of submergedcrossing-river tonnel which is 725m long and has a transversal section of M.6InX8.75m. For the design ofthe consAnction scheme, sediment dePosihon the in the excavated trench serves as an impoftaIltparameter. Physical mode exPeriments were then conducted to inveshgate the rate of sedim…     

EXPERIMENTAL STUDY ON EQUILIBRIUM CONCENTRATION OF DEBRIS FLOWS

Discussion open until 2002.EmunmL SwrY ONEQUII.thare CONCENTRATION OF DEBRIS rrOWSBin YU1AaSTsiCTThe paPe PresentS experimntal study of debris flows. The equiMm concentIation of solidparticle in the now is a hahon of the energy slope, density of solid Particle and kinetic ffichonange of paxtiles. The kinhc forhon angle is a funhon of intemal ffichon angle, the cOnCentrationof solid phocles and the mtalmum POssible concewhon. TO deteImin th6 hahon between thekinetic fficho…     

EXPERIMENTAL STUDY ON THE COHERENT STRUCTURE OF THE TURBULENT BOUNDARY LAYER IN OPEN-CHANNEL FLOW

1 INTRODUCTION The coherent structure of turbulence is the most important discovery of turbulence studies in the last several decades. The coherent structure is a joint spatial state (Liang, 1999). In this space, there exist all kinds of motions that are organized and related. Namely, strip structures, large vortical structures, and other organizing flows are present. In 1932, researchers found that turbulence wasn抰 a fully random phenomenon and came to realize that the repeated emergen…     

A STUDY ON VIBRATION REDUCTION IN HIGH-RISE STRUCTURES BY MULTI-TLDs

本文研究高层建筑利用调液阻尼器（ＴＬＤ）减小地震反应的方法。首先探讨了激励频率比、调谐频率比对减震效果的影响。在此基础上建立了具有不同ＴＬＤ设置方式的高层建筑体系的学模型和运动方程，首次提出了利用多个ＴＬＤ减小高层建筑多个振型的方法。最后通过数值算例验证了本文方法的有效性。