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您的检索式：作者名="Gilbert Le Bras"
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| 1 | Porous media grain size distribution and hydrodynamic forces effects on transport and deposition of suspended particles显示文摘The effects of porous media grain size distribution on the transport and deposition of polydisperse suspended particles under different flow velocities were investigated. Selected Kaolinite particles(2–30 μm) and Fluorescein(dissolved tracer) were injected in the porous media by step input injection technique. Three sands filled columns were used: Fine sand,Coarse sand, and a third sand(Mixture) obtained by mixing the two last sands in equal weight proportion. The porous media performance on the particle removal was evaluated by analysing particles breakthrough curves, hydro-dispersive parameters determined using the analytical solution of convection–dispersion equation with a first order deposition kinetics, particles deposition profiles, and particle-size distribution of the recovered and the deposited particles. The deposition kinetics and the longitudinal hydrodynamic dispersion coefficients are controlled by the porous media grain size distribution. Mixture sand is more dispersive than Fine and Coarse sands. More the uniformity coefficient of the porous medium is large, higher is the filtration efficiency. At low velocities, porous media capture all sizes of suspended particles injected with larger ones mainly captured at the entrance.A high flow velocity carries the particles deeper into the porous media, producing more gradual changes in the deposition profile. The median diameter of the deposited particles at different depth increases with flow velocity. The large grain size distribution leads to build narrow pores enhancing the deposition of the particles by straining. | Nasre-Dine Ahfir Ahmed Hammadi Abdellah Alem HuaQing Wang Gilbert Le Bras Tariq Ouahbi | 2017 | Journal of Environmental Sciences2017，29，3： | 6 |
| 2 | SEDIMENTATION AND CONSOLIDATION OF A HIGH WATER CONTENT SOIL显示文摘The permanent siltation of harbours and estuaries has led their administrative companies to undertake dredging operations in order to guarantee a minimal water depth required for free access to port infrastructures. This long and expensive work interferes with the port trade. Dredged material is injected into the sea with the creation of a maritime dump or stocked on earth in basins. In each case, there will be a formation of a high water content soil. This paper deals with the geotechnical formation of high water content soils by means of an experimental laboratory sedimentation/consolidation bench. We have devised and realized a controlled bench which allows us to analyze the natural soil formation under self weight. The tested soil settles in sedimentation/consolidation columns (1.5 m. in height, 100 mm in diameter). Pressure and density measurements in the tested soil are possible on the whole height of the vertical column. Values of density are obtained by gamma-densimetry. The precision of the measurements is +/-0.5% for the density and +/-3 Pa for the pressures. Each test is performed over 32 days with 17 intermediate times. An originality of this bench lies in the fact that it allows measurements with a good precision in density and pressure at a very early state of soil formation (first values at 1 .33 min. from the beginning of the test). The test we are presenting concerned the natural mud found in the Loire estuary (France) prepared to an initial concentration of 200 g/ 1 (density 1. 135). These measurements are studied in terms of evolution of total stress, excess pore pressure, void ratio and effective stress as related to time. For this test, we present the density and pressure measured profiles as well as the deduced effective stress curves, paths of particles and rates of consolidation. On a void ratio versus effective stress diagram, we clearly show the evolution of soil consolidating under self weight during the intermediate phase of its formation. The results of this study will greatly help in understanding the way soils and deposits behave in their environment. | ALEXIS Alain, LE BRAS Gilbert Researcher, Laboratoire de Genie Civil de Names Saint-Nazaire, IUT de Saint-Nazaire, Saint Nazaire,France PHD Student, Laboratoire de Genie Civil de Names Saint-Nazaire, IUT de Saint-Nazaire, Saint Nazaire,France Tel. 00 33 | 2000 | International Journal of Sediment Research2000，15，3： | 1 |
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