Un-resolved CFD-DEM method: An insight into its limitations in the modelling of suffusion in gap-graded soils

Cheng, Kuang; Zhang, Chunyu; Peng, Kairan; Liu, Hongshuai; Ahmad, Mahmood

doi:10.1016/j.powtec.2020.12.034

Cited by 27 publications

(12 citation statements)

References 34 publications

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“…Therefore, analyzing the actual particle size distribution, including even the finest soil particles, is desirable, using DEM, and calculating detailed pore flow using resolved coupling simulation. In addition, we aim to develop a simulator that can efficiently solve internal erosion in the ground by implementing a semi-resolved coupling [37,47] that combines a resolved coupling and an unresolved coupling. If this semi-resolved coupling method becomes available, it should be able to efficiently and in more detail determine the interaction between flow and soil particles in the ground, and it should apply to the numerical analysis of large-scale structures such as breakwaters.…”

Section: Discussionmentioning

confidence: 99%

“…However, the selected drag force due to the averaged Darcy velocity may need to be modified, or the contribution of particles smaller than the average size may need to be included. Cheng et al [47] also pointed out the limitation of the unresolved coupling model. They conclude that unresolved coupled simulations with the conventional drag force may be relatively smaller than the actual averaged force, thus overestimating the critical hydraulic gradient of the subject ground.…”

Section: Isph-dem Simulation Of Seepage Failure In Caisson-type Break...mentioning

confidence: 99%

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Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method incoprporated with Terzaghi's critical hydraulic gradient

Tsuji

Asai²,

Kasama

2022

Preprint

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This study develops a new numerical simulation model for rubble mound failure prediction caused by piping destruction under seepage flows. The piping has been pointed out as a significant cause of breakwater failure during tsunamis. Once boiling and heaving occur on the mound surface, the piping suddenly propagates in the opposite direction of seepage flow. For the seepage failure prediction, a coupled fluid-soil-structure simulator is developed by combining the ISPH for fluid and the DEM for rubble mounds and caisson blocks. The ISPH, a Lagrangian particle method for incompressible fluids, can simulate seepage and violent flows such as tsunamis. The DEM has been applied for discrete particle and rigid body simulations that include discontinuous deformation as in the rubble mounds failure and large displacement of the caisson block. ISPH-DEM coupling simulations have already been proposed as a technique for multi-phase flows. Still, the technique cannot reproduce the sudden onset of piping from a stable mound. Two simple assumptions are applied to reduce the numerical cost for the fluid-soil-structure simulators of a breakwater structure composed of rubble mound and the caisson block. Firstly, each rubble is modeled as an idealized spherical DEM particle with the mean diameter of rubble. The ISPH particle size is assumed to be the same size as the DEM particle. Under these assumptions, the unresolved coupling model between rubble mound particle and fluid, which obtains the interaction through empirical drag force, should be applied. Whereas the interaction between the fluid and the caisson block is fully resolved with the spatial resolution with the ISPH and DEM particle size. Our new contribution in this paper is how to model the interaction as an unresolved coupling between seepage flow simulated by ISPH and rubble mound particle modeled with DEM. Our original seepage failure experiment is simulated using the proposed ISPH-DEM coupling simulator. We recognized the conventional drag force models as the unresolved coupling model are insufficient to initiate the boiling and piping observed in the experiment. It may be due in one part to excessive averaging of flow velocities caused under unresolved coupling. Therefore, Terzaghi's critical hydraulic gradient is introduced to initiate the boiling and heaving. Unstable DEM particles, judged by Terzaghi's critical hydraulic gradient, gradually lose their mass to represent unresolved suspended fine rubble mound particles. Our models qualitatively reproduce the sand boiling and backward erosion in the opposite direction of the seepage flow, as shown in the experiment.

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Section: Discussionmentioning

confidence: 99%

Section: Isph-dem Simulation Of Seepage Failure In Caisson-type Break...mentioning

confidence: 99%

Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method incoprporated with Terzaghi's critical hydraulic gradient

Tsuji

Asai²,

Kasama

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…However, the selected drag force due to the averaged Darcy velocity may need to be modified, or the contribution of particles smaller than the average size may need to be included. Cheng et al [51] also pointed out the limitation of the unresolved coupling model. They conclude that unresolved coupled simulations with the conventional drag force may be relatively smaller than the actual averaged force, thus overestimating the critical hydraulic gradient of the subject ground.…”

Section: Isph-dem Simulation Of Seepage Failure In Caisson-type Break...mentioning

confidence: 99%

Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method enriched with Terzaghi’s critical hydraulic gradient

Tsuji

Asai

Kasama

2023

Adv. Model. and Simul. in Eng. Sci.

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This study develops a new numerical simulation model for rubble mound failure prediction caused by piping destruction under seepage flows. The piping has been pointed out as a significant cause of breakwater failure during tsunamis. Once boiling and heaving occur on the mound surface, the piping suddenly propagates in the opposite direction of seepage flow. For the seepage failure prediction, a coupled fluid-soil-structure simulator is developed by combining the ISPH for fluid and the DEM for rubble mounds and caisson blocks. The ISPH, a Lagrangian particle method for incompressible fluids, can simulate seepage and violent flows such as tsunamis. The DEM has been applied for discrete particle and rigid body simulations that include discontinuous deformation, as in the rubble mounds failure and large displacement of the caisson block. ISPH-DEM coupling simulations have already been proposed as a technique for multi-phase flows. Still, the technique cannot reproduce the sudden onset of piping from a stable mound. Two simple assumptions are applied to reduce the numerical cost for the fluid-soil-structure simulators of a breakwater structure composed of a rubble mound and the caisson block. Firstly, each rubble is modeled as an idealized spherical DEM particle with the mean diameter of the rubble. The ISPH particle size is assumed to be the same size as the DEM particle. Under these assumptions, the unresolved coupling model between rubble mound particles and fluid, which obtains the interaction through empirical drag force, should be applied. At the same time, the interaction between the fluid and the caisson block is fully resolved with the spatial resolution with the ISPH and DEM particle size. Our new contribution in this paper is how to model the interaction as an unresolved coupling between seepage flow simulated by ISPH and rubble mound particle modeled with DEM. Our original seepage failure experiment is simulated using the proposed ISPH-DEM coupling simulator. We identified the conventional drag force models as the unresolved coupling model are insufficient to initiate the boiling and piping observed in the experiment. It may be due in one part to excessive averaging of flow velocities caused by unresolved coupling. Therefore, Terzaghi’s critical hydraulic gradient is introduced to initiate the boiling and heaving. Unstable DEM particles, judged by Terzaghi’s critical hydraulic gradient, gradually lose their mass to represent unresolved suspended fine rubble mound particles. Our models qualitatively reproduce the sand boiling and backward erosion in the opposite direction of the seepage flow, as shown in the experiment.

show abstract

“…Yang et al (2019) improved the semi-resolved CFD-DEM model for seepageinduced fine particle migration. Cheng et al (2021) revealed that unresolved CFD-DEM models predict unreasonably high critical hydraulic gradients for suffusion in gap-graded soil columns packed under gravity.…”

Section: Introductionmentioning

confidence: 99%

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

Cao

Sun

Xie

et al. 2021

Preprint

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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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Un-resolved CFD-DEM method: An insight into its limitations in the modelling of suffusion in gap-graded soils

Cited by 27 publications

References 34 publications

Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method incoprporated with Terzaghi's critical hydraulic gradient

Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method incoprporated with Terzaghi's critical hydraulic gradient

Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method enriched with Terzaghi’s critical hydraulic gradient

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

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