Experimental investigation on the inherent and initial induced anisotropy of sand

Razeghi, Hamid Reza; Romiani, Hadi Mohamadzadeh

doi:10.1007/s12205-012-0373-7

Cited by 17 publications

(5 citation statements)

References 13 publications

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“…9 Razeghi and Romiani studied the influence of inherent and stress-induced anisotropy on the strength of sand by hollow cylinder torsion shear tests. 10 They observed that the anisotropic response of medium-dense sands strongly depended on the bedding angle of the sand.…”

Section: Introductionmentioning

confidence: 99%

A multi‐fidelity residual neural network based surrogate model for mechanical behaviour of structured sand

Zhou,

Yin,

et al. 2024

Num Anal Meth Geomechanics

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The structured sand presents significant interparticle bonding and anisotropy, resulting in significant differences in the physical and mechanical properties from the pure sand. This study proposes a new surrogate model based on the concept of multi‐fidelity residual neural network (MR‐NN) as an alternative to DEM simulation for predicting the mechanical behaviours of structured sand with different initial anisotropy and saving largely computational costs. The model is initially trained using low‐fidelity (LF) data to focus on capturing the main underpinning correlations between macroscopic mechanical parameters with inter‐particle properties and anisotropic state variables (i.e., microscopic fabric and tilting angle of sand), where the LF data are generated from previously proposed anisotropic macro‐micro quantitative correlation. Subsequent training on sparser high‐fidelity (HF) data is used to calibrate and refine the model with HF data generated from DEM simulations for anisotropic structured sand. Feedforward neural network (FNN) is adopted as the baseline algorithm for training models. The macroscopic anisotropic parameters of structured sand predicted by the surrogate model are compared with DEM simulations to examine its feasibility and generalization ability. Furthermore, the robustness of the surrogate model is examined by discussing the effect of LF data on the performance of MR‐NN. The superiority of the MR‐NN is further verified by comparing the performance of the trained MR‐NN with the one‐shot trained FNN based on the same HF data. All results demonstrate that the proposed surrogate model can provide a fast and accurate simulation of the anisotropic parameters of structured sand.

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Section: Introductionmentioning

confidence: 99%

A multi‐fidelity residual neural network based surrogate model for mechanical behaviour of structured sand

Zhou,

Yin,

et al. 2024

Num Anal Meth Geomechanics

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“…Despite the fact that natural soils are often consolidated under anisotropic conditions, most conventional laboratory tests are performed under isotropic consolidation -instead of anisotropic consolidation -to evaluate the soil strength parameters and stress-strain relations. Moreover, numerous studies have been conducted on the probable consequences of the overlooked initial anisotropy at the consolidation stage and their impacts on the behavior of sands (e.g., Iai et al 1992;Doanh et al 1997Doanh et al , 2012Doanh et al , 2013Dubujet and Doanh 1997;Akira Sato et al 1998;Kato et al 2001;Imam et al 2002a,b;Finge et al 2006;Hareb and Doanh 2012;Rodriguez and Lade 2013;Georgiannou and Konstadinou 2014;Razeghi andRomiani 2015, Ahmad andFakharian 2020).…”

Section: Introductionmentioning

confidence: 99%

Influences of initial anisotropy and principal stress rotation on the undrained monotonic behavior of a loose silica sand

2022

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Triaxial compression and extension tests have been conducted under different initial anisotropy conditions to investigate the undrained response of a crushed silica sand. The loose to medium specimens were prepared using the moist tamping method. Five stress paths with different stress ratios (q/p^') were employed to prepare anisotropically consolidated specimens. Several specimens were consolidated under a specific condition in which a stress rotation occurred under undrained monotonic shearing similar to a reversed cyclic shear stress loading during an earthquake. The effects of initial induced anisotropy at consolidation on the onset of liquefaction, phase transformation, and critical state are investigated within the framework of Anisotropic Critical State Soil Mechanics (ACSSM). In addition, fabric evolution during shearing towards the critical state is evaluated using bidirectional bender element tests. The results illustrate the fact that there is a unique anisotropic critical state representing anisotropic fabric, irrespective of initial anisotropy, and the states of stress. Similar to the critical state line, the phase transformation line has the same loci for different initial anisotropies.

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“…Symes et al [1] published a study on the anisotropy of soil under various principal stress directions. Several researchers [12][13][14][15][16][17] have previously investigated the anisotropic behavior of sand and clay using HCA tests, and the obtained results have suggested that the strength and stress-strain response of soil strongly depend on the change in the principal stress direction. Moreover, multiple researchers [18,19] have investigated the anisotropic behavior of soils subjected to principal stress rotation.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Anisotropy and Non-coaxiality of Frozen Standard Sand under Different Principal Stress Directions

Chen

Zhao

et al. 2022

Geofluids

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Owing to the limitations of the apparatus, the influence of its principal stress direction on the anisotropic behavior and non-coaxiality of frozen soil has not been fully considered in previous studies. At a temperature of -10°C, a series of hollow cylinder tests for frozen standard sand (FSS) was conducted under different directional angles of major principal stress and mean principal stresses in this study. The experimental results indicate that the stress-strain-strength anisotropy and non-coaxiality of the FSS are highly dependent on the principal stress direction. The stress components of the FSS vary linearly with increasing shear stress at different directional angles of the major principal stress and mean principal stresses. With a linear increase in shear stress, the strain components of the FSS exhibited a nonlinear increasing trend. The FSS strength gradually decreased as the directional angle of the major principal stress and the mean principal stresses in the test range increased. Under the different principal stress directions, the non-coaxiality of the FSS, non-coincidence of the direction of the principal strain increment and the principal stress direction, were observed. The directions of the principal strain increment and principal stress gradually tended to be coaxial as shear stress increased. Although the non-coaxial angle of the FSS increased gradually with an increase in the directional angles of the major principal stress, it did not change with the change in the mean principal stress. The non-coaxial angle of the FSS was observed to be as large as 35° in the early stage of shearing under different mean principal stresses.

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Experimental investigation on the inherent and initial induced anisotropy of sand

Cited by 17 publications

References 13 publications

A multi‐fidelity residual neural network based surrogate model for mechanical behaviour of structured sand

A multi‐fidelity residual neural network based surrogate model for mechanical behaviour of structured sand

Influences of initial anisotropy and principal stress rotation on the undrained monotonic behavior of a loose silica sand

Experimental Study on the Anisotropy and Non-coaxiality of Frozen Standard Sand under Different Principal Stress Directions

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