Experimental Analysis of Fine-Particle Migration during Ceramic Filtration Processes

Seepage-induced fine-particle migration that leads to a change in the conductivity of a soil matrix is referred to as internal instability. This could jeopardize the structural integrity of the soil matrix by initiating suffusion (or suffosion), a form of internal erosion. Susceptibility to suffusion has been studied mostly under extreme laboratory conditions to develop empirical design criteria, which are typically based on the particle size distribution. The physics governing the process have not been comprehensively uncovered in the classical studies because of experimental limitations. Mainstream evaluation methods often over-idealize the suffusion process, holding a probabilistic perspective for estimating constriction sizes and fines migration. Prospective studies on constitutive modeling techniques and modern computational techniques have allowed a more representative evaluation and deeper insight into the problem. Recent advances in sensing technologies, visualization, and tracking techniques have equally enriched the quality of the data on suffusion. This paper sets out to present the long-standing knowledge on the internal instability phenomenon in soils. An attempt is made to pinpoint ambiguities and underscore research gaps. The classical empirical studies and modern visualizing techniques are integrated with particle-based numerical simulations to strengthen the theoretical understanding of the phenomenon.

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Mechanical State of Gravel Soil in Mobilization of Rainfall-Induced Landslide in Wenchuan seismic area, Sichuan province, China

10.5194/esurf-2018-15 ◽

2018 ◽

Author(s):

Liping Liao ◽

Yunchuan Yang ◽

Zhiquan Yang ◽

Yingyan Zhu ◽

Jin Hu ◽

...

Keyword(s):

Fine Particle ◽

Void Ratio ◽

State Parameter ◽

Particle Migration ◽

Triaxial Tests ◽

Dry Density ◽

Mechanical State ◽

Consolidation Process ◽

Gravel Soil ◽

Seismic Area

Abstract. Although gravel soils generated by seismic shaking in Wenchuan earthquake area have subjected to natural consolidation process for nearly ten years, geological hazards, such as slope failures with ensuing landslides, frequently are haunting the area. In this paper, artificial flume model tests and triaxial tests were used to make close observation on the mechanical state of gravel soil in Wenchuan seismic area. The results showed that: (1) The timing and patterns of landslide initiations were closely related to their initial dry densities, and the initiation processes were accompanied with a variation of dry density and void ratio; (2) Fine particle migration in soil and coarse-fine particle content rearrangement contributed to the internal micro structure reorganization, which was supposed to be the main reason for variation of dry density and void ratio; (3) Gravel soils with unchanged grain compositions, if under the same hydrostatic compression, they approached to an identical critical void ratio to fail; (4) The mechanical state of certain sort of gravel soil can be identified by its relative position between state parameter (e, p') and ec-p' planar critical state line; (5) Gravel soil slope failed and then evolved into landslide under lasting rainfall leaching, while in gravel slope there co-existed soil dilatation and contraction, but the dilatation was dominant. Above research findings not only could be used to interpret landslide initiation but also would provide an insight for landslide warning forecast of gravel slope in seismic area.

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Study on Particle-Size Process on Internal Erosion of Grap-Graded Soil--Rock Mixtures of Different Fine Contents

10.22541/au.163543156.60699608/v1 ◽

2021 ◽

Author(s):

Zhilin Cao ◽

Weichen Sun ◽

qiang xie ◽

Zhihui Wu ◽

Xiang Fu ◽

...

Keyword(s):

Fine Particle ◽

Fine Particles ◽

Numerical Test ◽

Coupling Model ◽

Particle Migration ◽

Test Method ◽

Internal Erosion ◽

Coarse Particles ◽

Permeability Evolution ◽

Fine Content

Soil–rock mixtures are widely encountered in geotechnical engineering projects. The instability and failure mechanism of grap-graded soil–rock mixtures under rainfall conditions has always been the focus of geological disaster research. To deeply explore the mechanism of seepage deformation of soil–rock mixtures, an indoor physical permeability test that considers soil–rock mixtures with different fine contents was conducted, and a particle-scale numerical simulation test of the permeability evolution was carried out using the coupling model of PFC3D and ABAQUS. The test results showed that the spatial distribution of fine particle loss along the height direction could be divided into three areas: top loss, middle uniform, and bottom loss area. The “island” effect of coarse particles, which is caused by excessive fine content and makes the fine particles bear more load, was eliminated with the loss of fine particles. In this preset working condition of coarse and fine particle diameters, setting FC to 35% may be the best way to fill the voids between the coarse particles. Particle migration leads to a change in the load-bearing skeleton structure, thereby causing seepage deformation. Therefore, the particle-scale numerical test method can better reproduce the seepage deformation process of grap-graded soil–rock mixtures.

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