Theoretical Analysis and Experimental Research on Multiscale Mechanical Properties of Soil

Dong, Feng; Fang, Yingguang

doi:10.1061/(asce)gm.1943-5622.0000573

Cited by 12 publications

(11 citation statements)

References 22 publications

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“…When subjected to external loads, the soil-rock mixture, whose skeleton is composed of mineral particles of cross grain group scale, shows that the contact bond and cementation bond between the matrix particles are broken and microcracks are generated at the microscale (Feng and Fang, 2016); at the mesoscale, it is shown that the plastic shape distortion of the soil matrix is induced by the incompatible deformation between the soil matrix and rock block in the soil-rock cell; at the macroscale, it shows complex engineering mechanical behaviors such as nonlinear and zigzag stress-strain relationship of the soil-rock mixture (Xu et al, 2011). Therefore, the mechanical behaviors of soil-rock mixtures at different scales are not only coupled and related to each other, but also have certain independence.…”

Section: Multi-scale Coupled Shear Strength Theoretical Model Of Soil...mentioning

confidence: 99%

“…For the soil-rock cell, the natural granular and structural characteristics of the soil-rock mixture at the microscale cause its internal deformation to show significant discontinuity and nonlinearity, which is manifested as the gradient phenomenon of shear strain of the soil matrix connecting the rock block (Feng and Fang 2016). Strain gradients occur when the microstructures of the material undergo plastic shape distortion.…”

Section: Multi-scale Coupled Shear Strength Theoretical Model Of Soil...mentioning

confidence: 99%

“…For the actual soil-rock mixture, the size of the rock block is distributed in the sample. In order to consider the influence of the size of rock blocks on the strength characteristics of soil-rock mixtures, the number density function f(d) of rock blocks is introduced (Feng and Fang 2016). Its physical meaning is the percentage of the number of rock blocks with equivalent diameter d in the total number of rock blocks in the unit volume of soil-rock mixture, which can be determined by the grading function g(d) of rock blocks.…”

Section: Eshelby-mori-tanaka Equivalent Inclusion Average Stress Prin...mentioning

confidence: 99%

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A multiscale finite element method for soil-rock mixture

Liu¹,

Dong

2023

Front. Mater.

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Soil-rock mixture is a complex multi-phase composite geotechnical material, and its strength is determined by the physical properties of constituent multi-phase materials and their coupling mechanical response between different phases of materials. Based on the Eshelby-Mori-Tanaka equivalent inclusion average stress principle, a theoretical model of multi-scale coupled shear strength of soil-rock mixture considering the interaction effect of rock block and soil is established, and the rotational freedom reflecting the microscopic motion details of rock block is introduced. Moreover, a multi-scale coupled constitutive relationship of soil-rock mixture is derived and compiled into a multi-scale finite element program. Based on the large-scale direct shear test of soil-rock mixture, the model parameters of the multi-scale finite element method are determined, and then the multi-scale finite element program is used to simulate and predict the cross-scale deformation process of the soil-rock mixture slope. The results show that the multi-scale finite element method can effectively describe the influence of the mechanism of the micro motion characteristics of the soil-rock mixture on the macro mechanical response, and can effectively overcome the pathological mesh-dependency of the classical finite element method; the rotation displacement of the rock block is mainly concentrated within the shear zone of the slope. The maximum rotational displacement of rock blocks inside the soil-rock mixture slope is 40.7°, and the rotational displacement of rock blocks outside the shear zone is about 0°. The physical mechanism of the cross scale evolution of the shear band of the soil-rock mixture slope is that: the rotation of the rock blocks weakens the strain transmission ability between the rock block and the matrix soil, thus forming the concentration and development of the plastic strain, and finally leading to the penetration of the shear bands of the slope and the overall sliding failure.

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Section: Multi-scale Coupled Shear Strength Theoretical Model Of Soil...mentioning

confidence: 99%

Section: Multi-scale Coupled Shear Strength Theoretical Model Of Soil...mentioning

confidence: 99%

Section: Eshelby-mori-tanaka Equivalent Inclusion Average Stress Prin...mentioning

confidence: 99%

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A multiscale finite element method for soil-rock mixture

Liu¹,

Dong

2023

Front. Mater.

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“…Therefore, a large number of theoretical, experimental, and numerical simulation studies have been carried out around it. However, the deformation and force within granular matter are discontinuous on the microscopic scale, and the mechanical properties of the inside and the contact surface of particles are completely different [2,3], which make its mechanical properties more complicated than that of ordinary fluids and solids [2][3][4]. Moreover, the basic problems such as whether the granular matter can be regarded as elastic, the type of its stress control equation, and the general applicability of the static theory on different particle shapes, are still not completely clear and need to be further studied.…”

Section: Introductionmentioning

confidence: 99%

The experiment and analysis of the repose angle and the stress arch-caused stress dip of the sandpile

Fang

Guo

et al. 2021

Granular Matter

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The repose angle and characteristics of the vertical stress distribution beneath the sandpile can help to understand the physical and mechanical properties of the granular matter and guide the foundation design of the rock-soil deposits such as the rockfill dam and the storage structures of granular materials. Researches previously found that the stress dip phenomenon exists in piles constructed by the localized-source procedure, where the maximum vertical stress underneath the pile deviates from the center. The repose angle and the stress dip are affected by many internal and external factors and exhibit highly nonlinear and sensitive characteristics. However, the variation of the repose angle and the stress dip with influencing factors and the cause of the stress dip have not yet been fully explored. Based on the localized-source conical sandpile experiments and the discrete element method (DEM) simulation analysis, this paper studied the influences of the internal friction angle of granular matter and the construction history (the slowly raising funnel method SRFM and the fixed funnel method FFM) on the repose angle and the vertical stress dip beneath the pile; while the formation mechanism of the stress dip phenomenon was analyzed. The experimental results showed that the repose angle, physically different from the internal friction angle, has a relatively larger value and is positively related to the internal friction angle in the sandpile constructed by the FFM; the localized-source procedure and the internal friction angle are conducive to the formation of the macroscopic force chain arch structure in granular matter, which produces the arching effect and the stress shielding effect and leads to the stress dip beneath the pile; and the ratio of the stress dip RSD decreases with the increase of the local impact effect and the internal friction angle.

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“…However, few studies [40,41] to date have investigated the dynamic properties of non-clay minerals with similar particle size to clay particles in marine clay. In addition, the difference in particle size between coarse quartz particles and fine clay particles in marine clay was found significantly to affect the mechanical properties of marine clay, (e.g., cyclic strength [42] and peak strength [43]). The mineral composition of natural marine clay is furthermore complex, and its content in various minerals cannot be controlled artificially.…”

mentioning

confidence: 96%

Effects of Clay Mineral Composition on the Dynamic Properties and Fabric of Artificial Marine Clay

Shan

Wang

Cui

et al. 2021

JMSE

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Marine clays are easily affected by different mineral composition in cyclic load-based geological hazards. Therefore, based on analyzing the mineral composition of natural marine clay, it is the key to predict the dynamic properties of natural materials under cyclic loading by using quantitated artificial marine clay. In this study, the marine clay found in the South China Sea deltas was investigated. Based on the results of geological conditions and mineral composition analyses, raw non-clay minerals (such as quartz, albite) and clay minerals (such as Na-montmorillonite and kaolinite) were used to produce artificial marine clay, the dynamic properties of which were studied from the impact of mineral composition. Dynamic triaxial laboratory testing for artificial marine clay comprising various clay minerals was performed under identical test conditions. The artificial marine clay with high montmorillonite content exhibited slower development of strain, more sluggish growth in pore water pressure, more rounded hysteresis curves, greater stiffness, and more prolonged viscous energy growth than the clay with low montmorillonite content. In addition, the flocculated fabric of the artificial marine clay with high montmorillonite content demonstrated sufficient pore space changes, more uniform pore distribution, and larger specific surface area than the dispersed fabric of the clay with low montmorillonite content. The factors arising from the influence of montmorillonite may lead to microstructural and fabric changes, hinder the development of pore water, and increase intergranular contact stiffness as well as delay the cyclic strain amplitude at the breakpoint of viscous energy dissipation. In general, the results presented in this study confirm that clay minerals, especially montmorillonite, have significant influence on the dynamic properties of large strain.

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Theoretical Analysis and Experimental Research on Multiscale Mechanical Properties of Soil

Cited by 12 publications

References 22 publications

A multiscale finite element method for soil-rock mixture

A multiscale finite element method for soil-rock mixture

The experiment and analysis of the repose angle and the stress arch-caused stress dip of the sandpile

Effects of Clay Mineral Composition on the Dynamic Properties and Fabric of Artificial Marine Clay

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