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Sliding and damming properties of granular debris with different geometric configurations and grain size distributions

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Journal of Mountain Science 2024年第3期21卷 932-951页

作者： HE Ligeng TAN Longmeng YANG Xingguo ZHOU Jiawen LIAO Haimei College of Civil Engineering Guizhou UniversityGuiyang 550025China Quality Supervision and Law Enforcement Detachment of Guizhou Province Traffic Construction Engineering Guiyang 550081China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of granular debris during the occurrence of granular debris is essential for precise assessment and effective mitigation of landslide hazards in mountainous terrains. This research aims to investigate the impact of GSD and geometric configurations on sliding and damming properties through laboratory experiments. The geometric configurations were categorized into three categories based on the spatial distribution of maximum volume: located at the front(Type Ⅰ), middle(Type Ⅱ), and rear(Type Ⅲ) of the granular debris. Our experimental findings highlight that the sliding and damming processes primarily depend on the interaction among the geometric configuration, grain size, and GSD in granular debris. Different sliding and damming mechanisms across various geometric configurations induce variability in motion parameters and deposition patterns. For Type Ⅰ configurations, the front debris functions as the critical and primary driving component, with energy dissipation primarily occurring through inter-grain interactions. In contrast, Type Ⅱ configurations feature the middle debris as the dominant driving component, experiencing hindrance from the front debris and propulsion from the rear, leading to complex alterations in sliding motion. Here, energy dissipation arises from a combination of inter-grain and grain-substrate interactions. Lastly, in Type Ⅲ configurations, both the middle and rear debris serve as the main driving components, with the rear sliding debris impeded by the front. In this case, energy dissipation predominantly results from grainsubstrate interaction. Moreover, we have quantitatively demonstrated that the inverse grading in damming deposits, where coarse grain moves upward and fine grain moves downward, is primarily caused by grain sorting due to collisions among the grains and between

关键词： Landslide dam Geometric configuration Energy dissipation Inverse grading physical experiment

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Determination of the coefficient of rolling friction of an irregularly shaped maize particle group using physical experiment and simulations

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Particuology 2018年第3期16卷 185-195页

作者： Lijun Wang Rui Li Baoxin Wu ZhenchaoWu Zhenjun Ding College of Engineering Northeast Agricultural University Heilongjiang 150030 China

The coefficient of rolling friction is an important physical property of a maize particle. It is difficult to obtain the value of this coefficient because of the irregular shape of maize particles. This paper describes an approach that combines the discrete-element method （DEM） and a physical test to determine the coefficient of rolling friction of irregularly shaped maize particles. A novel test platform was used to obtain the maize particle＇s coefficient of restitution and the coefficient of static friction. EDEM software （DEM- Solutions, United Kingdom） was used to simulate the accumulation of maize particles on particles and on a zincified plate. The golden-section method was used to determine the range of the maize particle＇s coefficient of roiling friction. A single-factor test was used to determine the relationship between the maize particle＇s coefficient of rolling friction and their angle of repose. The results obtained from the EDEM simulation were compared with physical test results to determine the intergranular coefficient of rolling friction and the coefficient of roiling friction between maize particles and the zincified plate. Our study demonstrates that the angle of repose increases linearly with the coefficient of rolling friction of maize particles. The effect of the coefficient of rolling friction on the particle movement is studied. The physical verification test indicates that the obtained rolling friction of the maize particles is accurate. The findings of this paper provide a theoretical basis for maize-processing machine design and a discrete-element studv of the motion of maize particles inside such machines.

关键词： Coefficient of rolling friction Irregularly shaped particle Accumulation Simulation Golden-section method physical experiment

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Tight sandstone gas accumulation mechanisms and sweet spot prediction, Triassic Xujiahe Formation, Sichuan Basin, China

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Petroleum Science 2023年第6期20卷 3301-3310页

作者： Lin Jiang Wen Zhao Dong-Mei Bo Feng Hong Yan-Jie Gong Jia-Qing Hao Research Institute of Petroleum Exploration and Development PetroChinaBeijing100083China

The prediction of continental tight sandstone gas sweet spots is an obstacle during tight sandstone gas exploration. In this work, the classic physical fluid charging experimental equipment is improved, the combination of the gas migration and accumulation process with the pore network numerical simulation method is investigated, and application of the permeability/porosity ratio is proposed to predict the gas saturation and sweet spots of continental formations. The results show that (1) as the charging pressure increases, the permeability of the reservoir increases because more narrow pore throats are displaced in the percolation process;and (2) based on pore network numerical simulation and theoretical analysis, the natural gas migration and accumulation mechanisms are revealed. The gas saturation of tight sandstone rock is controlled by the gas charging pressure and dynamic percolation characteristics. (3) The ratio of permeability/porosity and fluid charging pressure is proposed to predict the gas saturation of the formation. The ratio is verified in a pilot and proven to be applicable and practical. This work highlights the tight sandstone gas migration and accumulation mechanisms and narrows the gap among microscale physical experiments, numerical simulation research, and field applications.

关键词： Tight sandstone gas Hydrocarbon migration and accumulation physical experiment Numerical simulation

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A review of breaking wave force on the bridge pier: experiment, simulation, calculation, and structural response

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第3期9卷 407-421页

作者： Kai Wei Jie Hong Mochen Jiang Wenyu Zhao School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China

In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge. This impact force might not only change the dynamic load pattern on the pier but also cause strong structural vibration, which may threaten the driving and structural safety of the bridge. Many studies have been carried out to study the issues in the aspect of wave flume experiment, numerical simulation, calculation of breaking wave force, and random vibration response of the structure. Considering the studies of breaking wave load on bridge piers are lack of systematic summaries, this paper presents a comprehensive and up-to-date literature review of breaking wave research and practice related to bridges. Firstly, a brief introduction is given, which includes recent cases of bridge failures caused by breaking waves. Then, both scientific and technical studies are reviewed, categorized into four aspects: experimental study, numerical simulation, analytical calculation of breaking wave force, and the structural response under breaking wave. Finally, Discussion is provided on four emerging ideas to investigate breaking wave forces on the pier from both science and engineering perspectives.

关键词： Breaking wave Wave force physical experiment Numerical simulation Calculation method Vibration characteristics

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Hydrodynamic Performance of A Dual-Floater Integrated System Com-bining Hybrid WECs and Floating Breakwaters

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China Ocean Engineering 2022年第6期36卷 969-979页

作者： FU Lei CHENG Yong School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

The high investment and low return of wave energy converters(WECs)seriously hamper their large-scale commercial application.The integration of WECs and floating breakwaters is conducive to enhance the competitiveness of wave energy conversion.The objective of this paper is to investigate the hydrodynamic performance of a WEC-breakwater integrated system combining an upstream oscillating water column(OWC)and a downstream oscillating buoy(OB)via numerical simulations and physical experiments.A nonlinear numerical wave flume using Star-CCM+software is employed to obtain calculated results,where a tiny transverse gap is set between the flume wall and the block surface to simulate a similar two-dimensional(2D)model.The corresponding physical experiments are also carried out in a practical wave flume to verified the numerical results.The comparison of the isolated and hybrid system shows that the hybrid design leads to the decreased conversion efficiency of each WEC,but improves the transmission performance of the hybrid system.The wave resonance between two devices causes the abrupt reduction of OWC efficiency and a positive correlation exists with the OB efficiency.The total efficiency of the hybrid system is raised by an optimal opening ratio,a shallow OWC draft and a short spacing distance.Except for the OWC draft,other design parameters have weak effect on the wave attenuation of the hybrid system.This paper can help understand hydrodynamics of the hybrid WECs integrated with breakwaters and improve their performances.

关键词： wave energy converters floating breakwater oscillating buoy oscillating water column numerical wave flume physical experiment

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experimental observation on water entry of a sphere in regular wave

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Theoretical & Applied Mechanics Letters 2023年第5期13卷 367-374页

作者： Qian Wang Changze Zhao Haocheng Lu Hua Liu Department of Engineering Mechanics MOE Key Laboratory of HydrodynamicsShanghai Jiao Tong UniversityShanghai 200240China

This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere impacting onto the water surface at the desirable wave phase.Four high-speed cameras focus locally to measure the high-precision size of the cavity evolution.Meanwhile,the aggregated field view of the camera array covers both the splash above the free surface and the entire cavity in the wave.The detailed methodologies are described and verified for the hardware set-up and the image post-processing.The theoretical maximum deviation is 1.7%on the space scale.The integral morphology of the cavity is captured precisely in the coordinate system during the sphere penetrates through the water at four representative wave phases and the still water.The result shows that the horizontal velocity of the fluid particle in the wave impels the cavity and changes the shape distinctly.Notably,the wave motion causes the cavity to pinch offearlier at the wave trough phase and later at the wave crest phase than in the still water.The wave motion influences the falling process of the sphere slightly in the present parameters.

关键词： physical experiment Water entry Free-falling sphere Regular wave

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Flow-induced vegetation uprooting in a meandering bend:experimental investigation

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International Journal of Sediment Research 2022年第3期37卷 399-410页

作者： Donatella Termini Alice Di Leonardo Department of Engineering University of Palermo

Vegetation uprooting is a complex process which depends on many interrelated factors. In this paper,attention is focused on the flow-induced uprooting in river bends, where the flow characteristics vary as effected by the channel’s curvature and its continuous changing in the downstream direction. Results are presented by an experimental work done in a high-amplitude meandering flume with mature herbaceous vegetation on the bed. In the first part of the paper, the variation along the bend of the geometrical(length, thickness, and radical architecture) and the mechanical(resistance force) characteristics of the roots are analyzed. In the second part of the paper, the transition from the condition of vegetation distributed on the bed to the condition of vegetation uprooted by the flow is experimentally examined.The results show that the flow-induced uprooting varies along the bend depending on the roots’ geometrical and mechanical characteristics which are, in turn, influenced by the variation of the water surface elevation along the bend itself. It has been found that lower values of the resistance force occur at the apex section where the roots are characterized by higher values of length and lower values of thickness and have radical apparatuses characterized by limited encumbrance, a high number of roots,and low bushyness. The flow-induced uprooting especially develops close to the outer bank along the channel reach between the bend entrance and the apex section, where the root resistance force and the water surface slope tend to decrease in value.

关键词： physical experiment River bend Resistance Flow disturbance Vegetation Uprooting

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Simple analytical model for depth-averaged velocity in meandering compound channels

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Applied Mathematics and Mechanics(English Edition) 2015年第6期36卷 707-718页

作者： Yuqi SHAN Chao LIU Maokang LUO College of Mathematics Sichuan University State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University College of Water Resource and Hydropower Sichuan University

A simple but applicable analytical model is presented to predict the lat- eral distribution of the depth-averaged velocity in meandering compound channels. The governing equation with curvilinear coordinates is derived from the momentum equation and the flow continuity equation under the condition of quasi-uniform flow. A series of experiments are conducted in a large-scale meandering compound channel. Based on the experimental data, a magnitude analysis is carried out for the governing equation, and two lower-order shear stress terms are ignored. Four groups of experimental data from different sources are used to verify the predictive capability of this model, and good predictions are obtained. Finally, the determination of the velocity parameter and the limitation of this model are discussed.

关键词： meandering compound channel simple analytical model lateral distribu-tion method physical experiment depth-averaged velocity

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The influence of perforated plates on wave transmission and hydrodynamic performance of pontoon floating breakwater

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Journal of Hydrodynamics 2018年第3期30卷 522-530页

作者：嵇春艳陈翔马小剑 Zhiming Yuan School of Naval Architecture and Ocean Engineering Jiangsu University of Science and Technology Department of Naval Architecture Ocean and Marine Engineering University of Strathclyde

In this study, a perforated pontoon floating breakwater（FB） consisting of an impermeable plate and a perforated plate was designed to untangle the effect of a perforated plate on wave transmission and hydrodynamic performance of floating breakwater. A series of 2-D physical model experiments were conducted to measure the wave transmission coefficient, tension acting on the mooring line, and motion response of FB under a regular wave. The experimental results of the motion responses and mooring lines indicated that the new perforated plate was evidently effective. Furthermore, the study also discussed and analyzed the influence of the perforated plate on transmission coefficients. The experimental results showed that the new perforated plate did not lead to obvious improvement in the transmission performance

关键词： Floating breakwater perforated plates physical experiment wave transmission coefficient motion responses

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Gas-water stratified flow patterns from electromagnetic tomography

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Petroleum Science 2009年第3期6卷 254-258页

作者： Wang Xiaoxing Wu Xiling School of Resources and Information Technology China University of Petroleum Beijing 102249 China

Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed ＂steps＂ whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced.

关键词： Electromagnetic tomography stratified flow gas-water numerical simulation physical experiment

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