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flume experiments to study fine-grain migration and its impact on slope stability

Journal of Mountain Science 2024年第10期21卷 3552-3566页

作者： WANG Baoliang WANG Quanwei LI Yong YAO Zhenguo WANG Hongfei Yellow River Engineering Consulting Co.Ltd. Zhengzhou 450003China Key Laboratory of Water Management and Water Security for Yellow River Basin Ministry of Water Resources(under construction)Zhengzhou 450003China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Key Laboratory of mountain Hazards and Surface Process Chinese Academy of SciencesChengdu 610041China

Fine grains migration is a primary cause of landslides and debris *** study investigates the effect of fine-grain migration on slope failure through flume experiments,focusing on the spatiotemporal characteristics and mechanisms of slope stability.A series of artificial rainfall flume experiments with varying rainfall intensities and slopes were conducted using soil samples collected from Wei Jia *** experiments monitored pore-water pressure,grain migration,and failure ***-size distribution parameters(μand Dc)were analyzed to understand the migration path and accumulation of fine *** experiments reveal that fine-grain migration significantly alters soil structure,leading to random blockage and interconnection of internal pore *** changes result in fluctuating pore-water pressure distributions and uneven fine-grain accumulation,critical factors in slope *** failures occur randomly and intermittently,influenced by fine-grain content in runoff and resulting pore-water pressure *** study highlights that fine-grain migration plays a vital role in slope stability,with significant implications for predicting and mitigating slope *** stochastic nature of fine-grain migration and its impact on soil properties should be incorporated into predictive models to enhance their accuracy and reliability.

关键词： Fine-grain migration Slope stability Pore-water pressure Artificial rainfall Soil structure flume experiments

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和水文地理模式相关的淤积三角洲前积层沉积速率的水槽实验（英文）

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地球环境学报 2011年第3期2卷 450-456页

作者： SUZUKI Taro ENDO Noritaka Department of Earth and Environmental Sciences Kanazawa University School of Natural System Kanazawa University

Foreset profiles of deltaic topography change corresponding to hydraulic conditions,and are influenced by water discharge and change rates of water *** investigate the correlation between the transition of deposition rates on the foreset and the change rate of water discharge of temporary waxing and subsequent waning flows,we perform experiments on silty deltas that developed under several different hydrographic *** findings are as follows:(1) Under flows with constant discharge,the deposition rate on the foreset was low at high water discharge and high at low water discharge because the separated flow became vigorous at high water discharge and prevented sediment supply onto the *** the water discharge is not constant,the deposition rate shifted concurrently with water discharge only at extremely low change rate.(2i) In a waxing flow at low(but not extremely low) increase rate,the deposition rate gradually decreased with some time lag.(2ii) In the case of high increase discharge,intense erosion on the topset caused by rapid waxing made a large amount of silt move onto the foreset and the deposition rate temporary increased.(3) With ample time after waning stage,the deposition rate recovered to that at constant low water discharge in all ***,the transitional processes depended on not only waning rate but also waxing rate at before waning stage.(3i) In the case of high decrease rate of water discharge,the deposition rate abruptly decreased regardless of increase rate.(3ii) Even in the case of low decrease rate of water discharge,if the increase rate before waning stage was high,the deposition rate abruptly decreased.(3iii) Only in the case where both the increase rate and the decrease rate were low,deposition rate gradually increased.

关键词： delta system hydrographic patterns deposition rate on the foreset flume experiments change of sediment flux

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SOME NEW DATA AND FORMULAS FOR RESISTANCE FLOW IN FLUVIAL OPEN CHANNELS

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Journal of Hydrodynamics 2011年第4期23卷 527-534页

作者： YANG Sheng-fa HU Jiang LI Dan-xun WANG Xing-kui GUO Yakun Department of River and Ocean Chongqing Jiaotong University Chongqing 400074 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China School of Engineering University of Aberdeen Aberdeen AB24 3UE UK

Flow resistance in fluvial open channels, especially in steep gravel-bed channels, still presents challenges to researchers and engineers. This article presents some new data from both the flume experiments and field measurements. Data analysis using the divided hydraulic radius approach shows that the relative roughness plays a significant role in the bed form resistance. A new set of formulas that incorporate the relative roughness are proposed. As compared with several existing formulas, the proposed formulas can be used to better estimate the bed form resistance.

关键词： open channel flow flow resistance relative roughness steep gravel-bed flume experiments field measurements

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A new statistical model of wave heights based on the concept of wave breaking critical zone

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Acta Oceanologica Sinica 2015年第5期34卷 81-85页

作者： YANG Jiaxuan LI Xunqiang ZHU Shouxian ZHANG Wenjing WANG Lei Institute of Noise and Vibration Naval University of Engineering Institute of Meteorology and Marine PLA University of Science and Technology National Key Laboratory on Ship Vibration and Noise College of Harbour Coastal and Offshore EngineeringHohai University

When waves propagate from deep water to shallow water, wave heights and steepness increase and then waves roll back and break. This phenomenon is called surf. Currently, the present statistical calculation model of surf was derived mainly from the wave energy conservation equation and the linear wave dispersion relation, but it cannot reflect accurately the process which is a rapid increasing in wave height near the broken point. So, the concept of a surf breaking critical zone is presented. And the nearshore is divided as deep water zone, shallow water zone, surf breaking critical zone and after breaking zone. Besides, the calculation formula for the height of the surf breaking critical zone has founded based on flume experiments, thereby a new statistical calculation model on the surf has been established. Using the new model, the calculation error of wave height maximum is reduced from 17.62% to 6.43%.

关键词： wave height statistical model surf breaking critical zone flume experiments

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Numerical prediction of turbidity currents on unsteady sediment-supply

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International Journal of Sediment Research 2013年第3期28卷 396-405页

作者： Ming-yang LIU You-cai TUO Rui-dong AN Jia LI State key Laboratory of Hydraulics and Mountain River Engineering Sichuan University(SKLHMRE) SKLHMRE

A three-dimensional(3D) numerical model of unstable turbidity currents is developed based on the mechanism of sediment transport and turbulence *** this model,numerical simulation of turbidity currents without subsequent supply of muddy water was conducted using the same parameters as were used in the flume *** evolution process of turbidity currents of completely losing supplies observed in the experiment was simulated by the model;validation of the numerical model and the algorithm was *** momentarily interrupted process is regarded as a special case of the gradually interrupted,based on the preceding numerical simulation validity,it is feasible to simulate the motion law of turbidity currents under losing gradually *** this method in this article,the characteristic of sediment-laden flow of losing gradually supplies was obtained,as well as its relationship between front velocity and sediment concentration.

关键词： Turbidity currents Sediment transport flume experiments Numerical simulation 3D model

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Amplification of flood discharge caused by the cascading failure of landslide dams

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International Journal of Sediment Research 2021年第3期36卷 430-438页

作者： Shoki Takayama Masamitsu Fujimoto Yoshifumi Satofuka Department of Science and Engineering Ritsumeikan University

The cascading failure of multiple landslide dams can trigger a larger peak flood discharge than that caused by a single dam failure. Therefore, for an accurate numerical simulation, it is essential to elucidate the primary factors affecting the peak discharge of the flood caused by a cascading failure, which is the purpose of the current study. First, flume experiments were done on the cascading failure of two landslide dams under different upstream dam heights, downstream dam heights, and initial downstream reservoir water volumes. Then, the experimental results were reproduced using a numerical simulation model representing landslide dam erosion resulting from overtopping flow. Finally, the factors influencing the peak flood discharge caused by the cascading failure were analyzed using the numerical simulation model. Experimental results indicated that the inflow discharge into the downstream dam at the time when the downstream dam height began to rapidly erode was the main factor responsible for a cascading failure generating a larger peak flood discharge than that generated by a single dam ***, the results of a sensitivity analysis suggested that the upstream and downstream dam heights, initial water volume in the reservoir of the downstream dam, upstream and downstream dam crest lengths, and distance between two dams were among the most important factors in predicting the flood discharge caused by the cascading failure of multiple landslide dams.

关键词： Landslide dam Cascading failure flume experiments Numerical simulation

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Bed roughness and grain sorting-an experimental study over fine to medium sand beds

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International Journal of Sediment Research 2017年第3期32卷 384-400页

作者： Barendra Purkait Dipanjan Das Majumdar Rajat Mazumder Geological Studies Unit Indian Statistical Institute Department of Geology University of Calcutta Department of Remote Sensing& GIS Vidyasagar University School of Biology Earth and Environmental Sciences University of New South Wales Dept. of Applied Geology Faculty of Engineering and Science Curtin University malaysia

The relation between grain-size distribution of the bed and in suspension was critically examined under a uniform flow velocity of 50 cm/s over two beds: one of mainly fine sands and the other of medium sands. Two sections-one 2.85 m downstream and the other 6.35 m downstream in the experimental channel-were selected for sampling to study the grain-sorting pattern in the vertical direction along the direction of transport. The shape and type of the grain-size distribution pattern were critically studied with height above the bed. The change in the distribution pattern has been attributed to the change of local bed roughness causing scouring against the protruded relatively coarse grains on the bed. Such trends are important to predict the nature of river bed topography. The sand of Bed-1 initially exhibits a log-skew-Laplace distribution at different heights of suspension. The distribution pattern, however,changes but this changing pattern is not consistent along the upstream side. For Bed-2, which initially exhibits a log-normal distribution, the same pattern persists from the height of suspension at 5 cm up to20 cm. Such consistency in log-normality is also observed at the downstream points of measurement. It is generally expected that the mean grain-size would reduce with increases of suspension height but the results of the experiments, in some occasions, differ significantly from the gradual fining upward *** result has been attributed to local changes of bed roughness arising from the protruded relatively coarse grains causing eddies, scouring, and turbulent phenomena which moves coarse particles higher in suspension adding a coarse tail to the distribution increasing the mean grain-size.

关键词： flume experiments Suspension height Uniform flow velocity Bed roughness Grain-size distribution Bed scouring Turbulent flow

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Uniform and graded bed-load sediment transport in a degrading channel with non-equilibrium conditions

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International Journal of Sediment Research 2020年第2期35卷 115-124页

作者： Khabat Khosravi Amir H.N.Chegini James R.Cooper Prasad Daggupati Andrew Binns Luca Mao School of Engineering University of Guelph School of the Built Environment Heriot-Watt University Department of Geography and Planning School of Environmental SciencesUniversity of Liverpool Department of Geography University of Lincoln

Bed-load transport plays a critical role in river morphological change and has an important impact on river *** there is good understanding of the role of the variation of river bed grain size on transport dynamics in equilibrium conditions,much less is understood for non-equilibrium conditions when the channel is either aggrading or *** particular,the relative role of different grain sizes in the promotion and hindering of the transport of coarse and fine fractions in a degrading channel has yet to be *** current study attempts to provide new understanding through a series of flume experiments done using uniform and graded sediment *** experiments revealed coarser grain-size fractions for a poorly-sorted sediment,relative to uniform-sized sediment,reduced the transport of finer grains and finer fractions enhanced the transport of coarse *** hinderingpromotion effect,caused by relative hiding and exposure of finer and coarse fractions,increased with bed slope and decreased with relative *** particular,as relative submergence increased,the graded fractions tended towards behaving more like their unifo rm-sized ***,the bed-load parameter of the graded fractions increased more with a rise in bed slope than observed for the uniformsized *** results revealed,for degrading channel conditions,such as downstream of a dam,bed-load equations developed for uniform bed sediment are inappropriate for use in natural river systems,particularly in mountain ***,changes in river bed composition due to activities that enhance the input of hill-slope sediment,such as fire,logging,and agricultural development,are likely to cause significant changes in river morphology.

关键词： Graded sediment Exposure Hiding flume experiments Non-equilibrium

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Evaluation of a gravel transport sensor for bed load measurements in natural flows

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International Journal of Sediment Research 2009年第1期24卷 1-15页

作者： Athanasios N.(Thanos) PAPANICOLAOU Mohamed ELHAKEEM Doug KNAPP Dept. of Civil and Environmental Engineering IIHR-Hydroscience and Engineering The University of Iowa 100 C. Maxwell Stanley Hydraulics Laboratory Research Scientist IIHR-Hydroscience and Engineering The University of Iowa 100 C. Maxwell Stanley Hydraulics Laboratory Engineer Seattle District Army Corps of Engineers

A recent acoustic instrument(Gravel Transport Sensor,GTS) was tested for predicting sediment transport rate(bed load rate) in gravel bed streams. The GTS operation is based on the particle collision theory of submerged obstacles in fluids. When particles collide with the GTS cylinder their momentum is recorded in the form of ping rates. The GTS is attractive for further consideration here because of its potential to provide continuous unattended local bed load measurements,especially in areas found in streams that access may be difficult under extreme conditions. Laboratory experiments coupled with numerical simulations for the same flow conditions were performed in order to determine the conditions under which particles of different size will hit the GTS cylinder and be able to register a ping rate. The GTS was able to detect the number of particles with diameter in the range of 15.9 to 25.4 mm,with reasonable accuracy,if the applied Shields effective stress τe=ττcr was in the range of 0.006 to 0.015. A drawback of the tested prototype GTS,however,was that it exerted increased resistance on the incoming particles. The added drag effects increased the overall resistance that was exerted by the flow on particles and thus increased the likelihood that particles will rest in the ambient region of the cylinder instead of hitting it. Numerical simulation of the flow around the GTS cylinder revealed that changing the prototype geometry from cylindrical to ellipsoid or rhomboid will increase the likelihood of the particles hitting the instrument under the same flow conditions failed by the original tested GTS cylinder.

关键词： Bed load measurement Gravel streams Gravel transport sensors flume experiments Numerical simulations

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Experimental study of cohesive sediment consolidation and its effect on seepage from dam foundations

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International Journal of Sediment Research 2016年第1期31卷 53-60页

作者： Guangming Tan Yiming Chen State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

Cohesive sediment consolidation causes remarkable changes in the stress field and seepage field of dams and reservoirs,due to variations in the dry density of *** study analyzed the physicochemical characteristics of cohesive sediments,and the consolidation mechanism to develop a dynamic model and status formula for the density during the initial stage of *** experiments were then conducted using cohesive and non-cohesive sediment samples to verify the derived formula by comparing the calculated values to measured sediment ***,the effect of sediment consolidation on seepage from a dam foundation was investigated using ABAQUS *** case study showed that the dry density of the sediment increased dramatically during the initial stage of consolidation(approximately 65%of the total growth),but it increased slowly in the later stage of the long *** water head of the upstream anti-seepage wall was substantially weakened due to the natural blanket behind the dam.

关键词： Cohesive sediments Consolidation flume experiments Dam foundation seepage

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