3D fibre architecture of fibre-reinforced sand

Soriano, Ilaria; Ibraim, Erdin; Andò, Edward; Diambra, Andrea; Laurencin, T.; Moro, P.; Viggiani, Gioacchino

doi:10.1007/s10035-017-0760-3

Cited by 32 publications

(25 citation statements)

References 41 publications

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“…For cross-anisotropic fibre orientation, we can further employ a simplified fiber distribution function ( ) (Michalowski & Čermák, 2002;Diambra et al, 2007;Soriano et al, 2017) to characterize the fibre concentration, where is the vertical angle of fibre inclination to the preferred fibre orientation plane (e.g., − plane in Fig. 1).…”

Section: Fibre Orientation Tensormentioning

confidence: 99%

“…where 0 , and are fitting parameters which can be determined based on the measured fibre orientation in FRS. It is shown by Diambra et al (2007) and Soriano et al (2017) that ( ) expressed in Eq. 11can give satisfactory description of crossanisotropic fibre orientation in an FRS sample.…”

Section: Fibre Orientation Tensormentioning

confidence: 99%

“…For the same FRS with preferred fibre orientation being horizontal, fibres are found to add significant enhancement to the soil strength in conventional triaxial compression, where the direction of major principal stress/strain increment is vertical, and almost negligible reinforcement in conventional triaxial extension with horizontal major principal stress/strain increment direction (Michalowski & Čermák, 2002;Diambra et al, 2013;Mandolini et al, 2018). This is caused by the relative orientation of fibres with respect to the developed tensile strains within the soil (Diambra et al, 2007;Soriano et al, 2017): the fibres' strengthening contribution is activated only when they are pulled in tension. Thus, it appears paramount to account for the effect of fibre orientation anisotropy in modelling the mechanical behaviour of FRS (Michalowski & Čermák, 2002;Diambra et al, 2013;Mandolini et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…An important feature of fibre reinforced sands (FRS) is the anisotropic fibre orientation caused by compaction during sample preparation or field construction (Michalowski & Čermák, 2002;Diambra et al, 2007;Soriano et al, 2017). Such anisotropic fibre orientation makes the mechanical behaviour of FRS dependent on the strain increment direction (Michalowski & Čermák, 2002;Diambra et al, 2013;Gao & Zhao, 2013).…”

Section: Introductionmentioning

confidence: 99%

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A multiaxial constitutive model for fibre-reinforced sand

Gao

Diambra

2021

Géotechnique

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Fibre orientation in fibre-reinforced sand (FRS) is highly anisotropic due to compaction during sample preparation or field construction. This makes the mechanical behaviour of FRS, such as strength and dilatancy, highly dependent on the strain increment direction. While constitutive models able to capture such anisotropic behaviour of FRS have been proposed for conventional triaxial compression and extension conditions only, this paper proposes for the first time a full anisotropic model for FRS formulated in the general multiaxial stress space. The new model is developed based on the assumption that the strain of FRS is dependent on the deformation of the sand skeleton. In turn, the fibre presence affects the void ratio and effective stress of the soil skeleton, which governs the elastic properties, dilatancy and plastic hardening of the FRS. The effect of anisotropic fibre orientation on the FRS behaviour is considered through an anisotropic variable which characterises the relative orientation between the loading direction tensor and fibre orientation tensor. The model does not require direct measurement of the stress-strain relationship of individual fibres. Though the model is for FRS under multiaxial loading conditions, the parameters associated with the fibre inclusion can be determined based on triaxial test results, provided that the orientation of fibres is known. The model has been used to predict the stress-strain relationship of fibre-reinforced Hostun RF (S28) sand under multiaxial loading conditions. Satisfactory agreement between the experimental data and model predictions is observed.

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Section: Fibre Orientation Tensormentioning

confidence: 99%

Section: Fibre Orientation Tensormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A multiaxial constitutive model for fibre-reinforced sand

Gao

Diambra

2021

Géotechnique

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“…Indeed, it is found by Ibraim et al [18] that the internal structure of FRS, particularly the distribution of fibers, has profound effect on the soil dilatancy (e a À e v relationship). Therefore, better model predictions could be achieved by accounting for the effect of fiber distribution in FRS [23,28,34]. In general, the model prediction gives reasonable prediction of the soil response, but it can be further improved in the following aspects.…”

Section: Polypropylene-reinforced Osorio Sandmentioning

confidence: 99%

Effective skeleton stress and void ratio for constitutive modeling of fiber-reinforced sand

Gao

Huang

2020

Acta Geotech.

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Inclusion of flexible fibers such as polypropylene and polyester is an effective method for soil improvement, as it significantly enhances the soil strength and ductility. A proper constitutive model is essential for assessing the stability and serviceability of fiber-reinforced slopes/foundations. A new method for constitutive modeling of fiber-reinforced sand (FRS) is proposed. It assumes that the strain of FRS is dependent on the deformation of the sand skeleton only, while the effective skeleton stress and effective skeleton void ratio, which should be used in describing the dilatancy, plastic hardening and elastic stiffness of FRS, are affected by fiber inclusion. The effective skeleton stress is dependent on the shear strain level, and the effective skeleton void ratio is affected by the fiber content and sample preparation method. A critical state FRS model in the triaxial stress space is proposed using the concept of effective skeleton stress and void ratio. Four parameters are introduced to characterize the effect of fiber inclusion on the mechanical behavior of sand, all of which can be easily determined based on triaxial test data on FRS, without measuring the stress-strain relationship of individual fibers. The model is validated by triaxial compression test results on four fiber-reinforced sands under loading conditions with various confining pressures, densities and stress paths. Potential improvement in the model for incorporating fiber orientation anisotropy is discussed.

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A study of wave propagation and stiffness anisotropy in anisotropically loaded granular material-synthetic fiber binary systems

Ren

Senetakis

et al. 2022

Granular Matter

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The influence of polypropylene fiber inclusion on the wave propagation parameters and stiffness anisotropy of granular materials was examined through vertically and laterally positioned bender elements, by which, shear wave velocities were measured leading to the quantification of elastic stiffness Gmax(vh), Gmax(hv) and Gmax(hh) (the first subscript corresponds to the direction of wave propagation and the second subscript corresponds to the direction of particle perturbation as v:vertical and h:horizontal). Various stress paths were considered to comprehensively study stiffness anisotropy of the specimens and grain-scale laboratory tests were additionally performed to provide, partly, some multi-scale insights into the mechanisms of wave propagation of the sandfiber granular composites. For the back-calculation of elastic stiffness from the wave propagation experiments, Biot's theory was adopted, in which case an equivalent density was used to interpret the high-frequency test results taking into account the relative movement of the solid and fluid phases, which approach provided much better convergency of the results from bender elements and resonant column tests. In this case we assumed that the solid skeleton is composed of the sand particles and the fibers. The test results indicated that when subjected to isotropic stress state, the presence of fibers led to a decrease of Gmax(vh) and Gmax(hv) but an increase of Gmax(hh). The extent of Gmax(hh) increase was dependent on the characteristics of the host sand and could be attributed to the structural anisotropy with preferred horizontal orientation of the fibers leading to more pronounced development of rigid-soft contacts in the vertical direction. The contribution of the rigid-soft contacts in stiffness reduction could be linked to the microscopic influence of the softer synthetic fibers in reducing the normal contact stiffness and increasing the energy dissipation of the granular system as the grain-scale experiments suggested. When subjected to anisotropic stress state, the stiffness anisotropy was affected by fiber content in a way that with increasing amount of fiber inclusion, the reduction of the stiffness anisotropy became larger. The stiffness anisotropy of the sand or sand-fiber binary system increased with the increase of the stress ratio. Further analysis of the test results revealed that stress induced anisotropy was directly linked to the influence of deviatoric stress on the volumetric strain.

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3D fibre architecture of fibre-reinforced sand

Cited by 32 publications

References 41 publications

A multiaxial constitutive model for fibre-reinforced sand

A multiaxial constitutive model for fibre-reinforced sand

Effective skeleton stress and void ratio for constitutive modeling of fiber-reinforced sand

A study of wave propagation and stiffness anisotropy in anisotropically loaded granular material-synthetic fiber binary systems

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