Suffusion is a selective erosion of fine particles under the effect of seepage flow within the matrix of coarser particles. This complex phenomenon appears as a combination of three processes: detachment, transport and possible filtration of finer fraction. It can induce a change in particle size distribution, porosity and hydraulic conductivity of the material. With the objective to characterize the suffusion susceptibility, downward seepage flow tests were conducted. Four different cohesionless soils were tested under hydraulic gradient controlled conditions or under flow rate controlled conditions. This study shows the significant effect of hydraulic loading history on the value of critical hydraulic gradient.Moreover, method characterizing the erosion susceptibility based on rate of erosion does not lead to a unique characterization of suffusion process for different types of hydraulic loading. The new analysis is based on energy expended by the seepage flow and the cumulative eroded dry mass. The results demonstrate that this approach is more effective to characterize suffusion susceptibility for cohesionless soils.

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. Building new entities from existing titanium part by electron beam melting: microstructures and mechanical properties.

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Internal erosion processes in earth structures and their foundations may increase the failure risk of such structures. Suffusion, one of the main internal erosion processes, selectively erodes the fine particles which move through the voids formed by the coarser particles. In literature, several suffusion susceptibility investigations were already published with various tested specimen sizes.However, the influence of the specimen size on suffusion susceptibility is not well established. The objective of this study is to investigate this influence by comparing results of suffusion tests performed on six different soils, with two different sized devices. First, this study highlights the complexity of suffusion process which is a combination of three processes: detachment, transport and possible filtration of the finer fraction. The results also show a decrease of the critical hydraulic gradient with the size of the specimen. The proposed interpretative method is based on the energy expended by the seepage flow and the cumulative loss dry mass. This method permits to obtain the same suffusion susceptibility classification for both specimen sizes.

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