Efficient Approach to Characterize Strength Anisotropy in Soils

A Rotational Haar Wavelet Transform (RHWT) method is developed to characterize the fabric of particulate assemblies from two-dimensional images. A Maximum Energy Ratio Ψ reveals the fabric direction and its intensity. The method is implemented on 12 sand and 3 rice specimens of various shapes. It was shown that Ψ may be expressed in terms of a material's aspect ratio and relative density. A material fabric classification system based on Ψ is proposed. The parameter also defines the fabric tensor for cross anisotropic material. Scanning electron microscope images of kaolinite clay and several rock images are also analyzed.

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“…In soil mechanics and constitutive modeling, the fabric of soil is usually quantified by a fabric tensor [43][44][45][46][47][48]53]:…”

Section: Fabric Tensor From Rhwt Resultsmentioning

confidence: 99%

Particulate material fabric characterization by rotational haar wavelet transform

Zheng

Hryciw

2017

Computers and Geotechnics

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“…Analysis of recent research and publications. The anisotropy of soil media in contact with the rear faces of spacer structures is confirmed by numerous domestic and foreign experimental studies [1][2][3][4]. The manifestation of anisotropy is associated with the heterogeneity of layered soil bases and the peculiarities of the laying of soil particles when washing artificial fillings.…”

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confidence: 81%

Аccounting the Seismic Component of the Lateral Pressure of an Heterogeneous Anisotropic Soil on Massive Hydrotechnical Structures

Voytenko¹

2020

BOSACEA

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Abstract. Strength anisotropy is characteristic of layered soil bases and has been confirmed by numerous tests. The relevance and novelty of this research is to study the effect of the seismic factor on the active pressure of the friable soil medium having strength anisotropy. A numerical experiment was carried out using a specially developed computer program, the algorithm of which used the method for determining the lateral pressure of a heterogeneous anisotropic soil, taking into account the seismic effect. The proposed method is based on the solutions of the classical theory of Coulomb, the seismic component is taken into account on the basis of the static theory of the earthquake stability of structures. We considered a vertically ideally smooth wall in contact with a two-layer incoherent soil medium, the anisotropy of the strength properties of which is represented by hodographs of friction angle. The layers are parallel, no surface load. A numerical research was to determine the parameters of the active pressure of the soil of the lower layer during rotation of the hodograph of friction angle with steps of 300. We used 4 hodographs: 1) φ1=150-200; 2) φ2=200-250; 3) φ3=250-300; 4) φ4=300-350 with a horizontal plane of isotropy. Seismic impact was taken into account by the seismicity coefficient, taken equal to depending on the scale 0.025 (7), 0.05 (8), 0.1 (9). The horizontal orientation of the seismic force and with an angle of 200 to the horizontal plane was set. The obtained results make it possible to evaluate the seismic effect on the lateral pressure of anisotropic soil by comparing it with the corresponding indicators obtained earlier without taking into account the seismic factor. An analysis of computer solutions indicates the increase of the active pressure in seismic conditions by 14%-45% compared with the same indicator, which was determined without taking into account the seismic factor.

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“…The combined tensor of the fabric tensor and the stress tensor was proposed (Tobita, 1988) and introduced into an isotropic strength criterion to describe the strength characteristics of transversely isotropic soils (Yao et al, 2017). Additionally, the joint invariant of the stress tensor and fabric tensor has been defined (Li & Dafalias, 2002;Dafalias et al, 2004) and used to develop the strength criteria for transversely isotropic soils (Gao et al, 2010;Gao & Zhao, 2012). Thirdly, the method of projecting the microstructure tensor onto the generalized loading direction was proposed to establish transversely isotropic strength criterion by defining an anisotropic parameter (Pietruszczak & Mroz, 2000;Pietruszczak & Mroz, 2001).…”

Section: Introductionmentioning

confidence: 99%

A novel transversely isotropic strength criterion for soils based on a mobilised plane approach

Liang

et al. 2019

Géotechnique

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The peak shear strength rules of transversely isotropic soils are stress state dependent and dependent on relative orientation between bedding plane and principal stress. Accordingly, the shear strength of transversely isotropic soils exhibits two primary characteristics: (i) the strength curve on the deviatoric plane is asymmetrical with respect to three principal stress axes; (ii) the shear strength changes with the direction angle of the bedding plane when the intermediate principal stress coefficient is a constant. In this paper, the mobilized plane is introduced and used to reveal the failure mechanism of soils. By projecting the microstructure tensor of transversely isotropic soils onto the normal of the mobilized plane, the directionality of the transversely isotropic soils is introduced into the friction rules on the mobilized plane, and a transversely isotropic strength parameter is proposed. The proposed strength parameter can extend isotropic strength criteria into transversely isotropic strength criteria. This mobilized plane approach is used to establish a novel transversely isotropic nonlinear unified strength criterion (TI-NUSC). The difficulty to establish a unified description of the asymmetrical strength curve and its evolution with direction angle is overcome by the established criterion. Comparisons between available test results and the TI-NUSC shows that the TI-NUSC can successfully describe these two primary peak strength characteristics.

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Efficient Approach to Characterize Strength Anisotropy in Soils

Cited by 36 publications

References 43 publications

Particulate material fabric characterization by rotational haar wavelet transform

Particulate material fabric characterization by rotational haar wavelet transform

Аccounting the Seismic Component of the Lateral Pressure of an Heterogeneous Anisotropic Soil on Massive Hydrotechnical Structures

A novel transversely isotropic strength criterion for soils based on a mobilised plane approach

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