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Experimental Studies on Debris Flow with Logs Focusing on Specific Weight Difference of Log Species

Journal of Mountain Science 2013年第2期10卷 315-325页

作者： Haruki WATABE Takahiro ITOH Kazuhiko KAITSUKA Shigeki NISHIMURA Nippon Koei Co. Ltd.2304InariharaTsukubaIbaraki 300-1259Japan

There are many experimental approaches,field investigations and numerical calculations for movements of woods in a clear water and debris ***,kinematic conditions for accumulated logs and the interactions between a main flow and logs have not been fully *** for woods need taking into account the characteristics of tree species such as conifer and broad-leaf trees and of shapes such as root swells and *** the present study,we focus on the differences in specific weight of conifer and broad-leaf trees with some moisture in a sediment-water mixture flow with narrow flow width,and consider that conifer and broad-leaf tree are floating and submerged solid phase,*** tests are conducted in steady flow of clear and debris flow over a rigid bed in order to evaluate conifer and broad-leaf tree movement in clear water and debris *** data indicates that dimensionless transverse diffusion coefficient can be 0.1 to 0.4 and 0.3 to 0.9 in flow *** diffusive characteristics seem to be independent of Reynolds number and Froude number,but dependent of bed slope,i.e.,gravity,though detailed considerations are needed to discuss about flow characteristics such as spatial eddy structures,momentum transfer induced by interactions of logs and so on.

关键词： Debris flow Driftwood Specificweight Log flume test

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Experimental study on the moving characteristics of fine grains in wide grading unconsolidated soil under heavy rainfall

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Journal of Mountain Science 2017年第3期14卷 417-431页

作者： CUI Yi-fei ZHOU Xiao-jun GUO Chao-xu Department of Civil and Environmental Engineering Hong Kong University of Science and TechnologyClear Water BayHong KongChina China Merchants Chongqing Communications Research&Design Institute Chongqing 400067China Fujian Academy of Building Research Pujian Key Laboratory of Green Building TechnologyFuzhou 350025China Fuzhou University Fuzhou 350108China

The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.

关键词： Wide grading unconsolidated soil Fine particle migration Soil failure Landslide Debris flow initiation flume test Heavy rainfall

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Numerical Simulation of Debris Flow Runout Using Ramms:A Case Study of Luzhuang Gully in China

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Computer Modeling in Engineering & Sciences 2019年第12期121卷 981-1009页

作者： Jianjun Gan Y.X.Zhang Jiangxi Engineering Research Center of Water Engineering Safety and Resources Efficient Utilization Nanchang Institute of TechnologyNanchangChina School of Computing Engineering and MathematicsWestern Sydney UniversityNSW2751Australia

This study proposes a comprehensive method,which consists of field investigation,flume test and numerical simulation,to predict the velocity and sediment thickness of debris *** velocity and sediment thickness of the debris flow in mountainous areas can provide critical data to evaluate the geohazard,which will in turn help to understand the debris *** flume test of this debris prototype can provide friction coefficient and viscosity coefficient which are important for numerical simulation of debris *** relation between the key parameters in the numerical modelling using the Voellmy model and debris-flow rheology is *** simulation of a debris flow that occurred in Luzhuang gully,it is observed that the debris flow runout determined by the Voellmy model was well consistent with that obtained from field investigation and flume test,demonstrating the effectiveness of this *** relationship between the Voellmy model and debris flow runout is also proposed.

关键词： Simulation approach debris flow flume test Voellmy model Luzhaung gully

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MECHANISM OF ARMORING PHENOMENA

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International Journal of Sediment Research 1990年第1期 49-55页

作者： Shinji Egathira and Kazuo Ashida Associate Professor, Disaster Prevention Research institute, Kyoto University. Professor, Disaster Prevention Research Institute, Kyoto University.

It is indicated that armor coats are formed even if all the sediment particles of the river ho move. Such armor coats can not be described in terms of selective entrainment. In this study, the mechanism on the formation of armor coat is investignted, first, with the flume data. A mathematical model, in which the processes of particle exchange within bed layers as well as of the selective entrainment are taken into account, is presented This model is analyzed numerically and compared with experimental data.

关键词： bed armoring Selective entrainment Particle exchange flume test Mathematical model Bed layer.

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