Factors affecting rainfall-induced flowslides in laboratory flume tests

Géotechnique ◽  
2001 ◽  
Vol 51 (7) ◽  
pp. 587-599 ◽  
Author(s):  
G. Wang ◽  
K. Sassa
1983 ◽  
Vol 40 (S1) ◽  
pp. s35-s43 ◽  
Author(s):  
Mary P. Kendrick ◽  
B. V. Derbyshire

A brief review has been made of five hydraulic investigations of port siltation carried out by various international laboratories. The ports studied are distributed throughout the tropics from South America to Indonesia and the factors affecting sediment supply and distribution either directly or indirectly have been summarized. In spite of local variations, the similarity of many features suggests the existence of a common mechanism of sediment transport.Twenty months of field measurements at one of the ports demonstrated that turbidity in the water column is low from surface to 0.15 m above the bed. These measurements, together with those from flume tests on the behavior of local mud in currents, indicated that siltation is not solely due to deposition of silt suspended in the main body of flow. Further wave flume tests showed that under certain conditions, a shallow, highly turbid layer forms on the bed, capable of being transported by weak tidal currents without significant vertical mixing. Supplementation of field measurements of water movement with more detailed hydraulic model measurements permitted the formulation of a siltation mechanism.Appraisal of results suggests the most important immediate source of the silt to be the shallow coastal mud banks. Waves produce the turbid, near-bed layer which is transported by littoral currents into port approach channels for redistribution by the prevailing residual current, itself a function of fluvial/tidal interaction.Key words: siltation, dredging, silt movement, flocculation, waves, tides, river flow, residual currents


1992 ◽  
Vol 29 (3) ◽  
pp. 405-417 ◽  
Author(s):  
Angela A. G. Küpper ◽  
Norbert R. Morgenstern ◽  
David C. Sego

Laboratory flume deposition tests were carried out to study the physical phenomena associated with the deposition of a sand slurry to form a hydraulic fill. The experimental apparatus was carefully designed to minimize flume-wall effects on the flow and to allow discharge of slurry of constant composition for an indefinite period of time. Slurry concentration and flow rate were varied independently to study their effects on characteristics of the fill such as geometry, grain-size distribution, and density. Three different sands were used to evaluate the influence of the mean grain size. Key words : hydraulic fill, flume tests, sand, profile, slope, density.


2007 ◽  
Vol 44 (9) ◽  
pp. 1128-1136 ◽  
Author(s):  
Fawu Wang ◽  
Hiroki Shibata

The mobility of flowslides is influenced by various factors. In this paper, laboratory flume tests were used to evaluate the influence of soil permeability using different soils with different permeabilities in a model slope, while keeping the slope condition and artificial rainfall intensity constant. It was found that the permeability of soil has a significant influence on the initialization of flowslides and that there is an optimal soil permeability existing for the mobility of flowslides when rainfall intensity is kept constant.


2022 ◽  
Vol 10 (1) ◽  
pp. 76
Author(s):  
Ruigeng Hu ◽  
Xiuhai Wang ◽  
Hongjun Liu ◽  
Hao Leng

A novel scour protection approach for pipeline using the Ionic Soil Stabilizer (ISS) solidified soil was proposed in this study. The ISS-solidified slurry can be poured adjacent to the pipeline immediately after it was placed, or in the growing scour holes. In the present study, the first type was utilized as the scour protection layer around the pipeline. A series of laboratory flume tests were conducted to validate the protective capacity of ISS-solidified slurry for the pipeline in waves and combined waves and current. Then, the scanning electron microscope (SEM) tests and pore size tests were carried out, respectively, to investigate the mechanism of ISS-solidified slurry for scour protection around the pipeline. Finally, the effects of the ISS-solidified layer for liquefaction stability of non-cohesive subsoil were evaluated. The results indicated that the ISS-solidified slurry is a reliable, economic approach for scour protection around pipelines in the ocean environment. It is noteworthy that if a non-cohesive soil layer underlies the ISS-solidified slurry, it is vulnerable to suffer accumulated liquefaction due to the dense crust structure of the ISS-solidified layer, so the adverse effects for accumulated liquefaction should be considered carefully due to the set of the ISS-solidified layer.


1990 ◽  
Vol 27 (5) ◽  
pp. 692-696 ◽  
Author(s):  
J. W. Kamphuis ◽  
P. N. Gaskin ◽  
E. Hoogendoorn

Erosion tests were carried out on four natural intact cohesive soils from Ontario using laboratory flume tests with both clear water and water with sand in suspension. It was found that erosion was initiated at discontinuities. The critical shear stresses were low and were not related to the geotechnical properties of the soils. Higher rates of erosion occurred with the sand suspension, and erosion appeared to be controlled by the movement of the sand particles. It is suggested that where the eroding water contains particles in suspension, such as in river beds and along shorelines of cohesive soil, erosion may be controlled by the size of the particles rather than the properties of the cohesive soil or the eroding water. Key words: erosion, cohesive soil, flume test.


Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.


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