Measurements and Numerical Simulations of Inherent Stiffness Anisotropy in Soft Taipei Clay

Teng, Fuchen; Ou, Chang‐Yu; Hsieh, Pio-Go

doi:10.1061/(asce)gt.1943-5606.0001010

Cited by 40 publications

(13 citation statements)

References 36 publications

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“…">IntroductionUnder natural conditions, the soil commonly exists in a normally consolidated state. However, with construction activities, such as excavation of foundation pits [13,41, 56], tunnel excavation [25, 48,51], embankment slope lling [9,20,24], the soil undergoes loading and unloading, changes in horizontal and vertical stresses, which cause the consolidation state to transition from the original isotropic consolidation to anisotropic consolidation. Many studies have emphasized the necessity of considering the anisotropy of the soil when designing and analyzing geological structures [9,20,24].…”

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confidence: 99%

WITHDRAWN: Effect of matric suction on stress-induced anisotropy behavior of unsaturated clay

Su,

Cai,

et al. 2024

Preprint

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Lots of geotechnical engineering problems are closely related to the anisotropic behavior of unsaturated soils. In this paper, suction-controlled, consolidated, drained triaxial shear tests were conducted on clay under unsaturated conditions. For unsaturated clay, the effects of matrix suction (suctions of 30 kPa, 100 kPa, and 200 kPa), initial stress ratio (R1 = 0.5 and 1) and subsequent stress ratio (R2 = 1, 2 and 3) on the hydro-mechanical behavior were studied, and the evolution of water retention, stress-induced anisotropy characteristics and critical state parameters under different stress paths were obtained. The stress path exerted a substantial influence on the water retention capacity of the clay, and the initial stress ratio was found to be the determining factor for the air entry value of the clay. Under identical initial stress ratio conditions, the water retention capacity of the clay was observed to diminish commensurately with an increase in the subsequent stress ratio. As suction increases and subsequent stress ratios escalate, the specimen transitions from a state of shear shrinkage to dilatancy, the peak shear strength (qf) and initial stress ratio change from negatively to positively correlated, while the critical state volumetric strain (\(\varepsilon _{{\text{v}}}^{{\text{c}}}\)) and initial stress ratio are positively to negatively correlated, and the anisotropy of unsaturated clay undergoes a transformation from negative correlation to positive correlation with the subsequent stress ratio. The critical state saturation (\(S_{r}^{{\text{c}}}\)) exhibits a negative correlation with the initial stress ratio and subsequent stress ratio. Under the same stress path and different matrix suctions, there exists a unique critical state line in the p'-q plane passing through the origin, with its slope is critical state effective stress ratio (M'). The initial stress ratio determines the range of variation for the M' value, which is positively correlated with the subsequent stress ratio.

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confidence: 99%

WITHDRAWN: Effect of matric suction on stress-induced anisotropy behavior of unsaturated clay

Su,

Cai,

et al. 2024

Preprint

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“…The ratios of (G0(a=90°)/G0(a=0°)) are 1.14 and 1.12 for unsaturated sand and saturated sand, respectively. Bellotti et al (1996), Pennington et al (1997), Yamashita et al (2005), Hight et al (2007), and Teng et al (2013) demonstrated that the shear moduli in the horizontal plane were higher than those in vertical plane. Ng and Yung (2008) proved that the increase of matric suction from 0 kPa to 50 kPa induced the increase of the shear modulus ratio (G0(hh)/G0(hv)) from 1.03 to 1.05.…”

Section: The Degree Of Anisotropymentioning

confidence: 92%

Effects of inherent anisotropy on G0 of unsaturated sand

Toyota

Takada

2019

JGS Special Publication

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Inherent anisotropy, resulted from sediment process, is an important aspect when considering the behavior of sandy soils. Also, accurate initial shear modulus G0 at very small strain is an essential parameter in many seismic designs and analyses of underground structures. In this research, the influences of inherent anisotropy on G0 were investigated by conducting a series of triaxial tests employed both local small strain (LSS) measurement technique and bender element (BE) method. Specimens were prepared using air pluviation method in an inclined container at different angles to create the inherent anisotropy induced by orientation of sand particles. The experimental results obtained on both saturated and unsaturated sands indicate that G0 was affected by depositional angle of the specimen. Moreover, those results showed greater G0 on unsaturated sand than that on saturated sand because of the application of matric suction.

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“…Small-strain stiffness and its variation along different stress paths are key factors in predicting ground deformations induced by geotechnical projects (deep excavation) in soft clays [1][2][3][4]. Meanwhile, the anisotropy in initial soil stiffness has been observed in numerous field and laboratory experiments, which is frequently disregarded by existing models [5][6]. Hence, constitutive modeling of the anisotropic small-strain stiffness behavior is of significant importance.…”

Section: Introductionmentioning

confidence: 99%

Constitutive modeling of anisotropic small-strain stiffness behavior of Shanghai soft clay

Chen,

Gu,

Shi

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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Small strain stiffness plays an important role in determining the deformation of geotechnical engineering in soft soils. To model the anisotropic small strain stiffness behavior of soft clay, an enhancement to the bounding surface plasticity model is proposed. This enhancement involves incorporating the anisotropy in soil stiffness at very small strains and its non-linear degradation. Small strains are considered via cross-anisotropy elasticity, while the concept of intergranular strain is used to reflect the non-linear degradation of stiffness with strains and the effect of recent stress history. Using the proposed model, the triaxial test results on K0 consolidated Shanghai clay specimens are simulated to investigate the model’s performance. In the simulation, three typical shear stress paths are adopted. The comparison of the model simulations against experimental evidence is discussed, where the effects of anisotropy in initial soil stiffness and stress-induced anisotropy on the variation of small-strain stiffness, pore pressure, and shear-volume coupling response are highlighted.

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Measurements and Numerical Simulations of Inherent Stiffness Anisotropy in Soft Taipei Clay

Cited by 40 publications

References 36 publications

WITHDRAWN: Effect of matric suction on stress-induced anisotropy behavior of unsaturated clay

WITHDRAWN: Effect of matric suction on stress-induced anisotropy behavior of unsaturated clay

Effects of inherent anisotropy on G0 of unsaturated sand

Constitutive modeling of anisotropic small-strain stiffness behavior of Shanghai soft clay

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