Comparisons of constitutive models for anisotropic soils

Kim, Dae Kyu

doi:10.1007/bf02829164

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…The strain history dependency is therefore introduced into the kinematic hardening mechanism. Based on the work of Kim and introducing the state dependency via Been's parameter, in a similar way as in Maleki et al . , the evolution of the kinematic hardening variable η is defined by the following equation:

d η = α \frac{1 + e}{λ - κ} {(\frac{p^{'}}{{italicp}_{a}})}^{- ψ} (\frac{s}{3 p^{'}}) Dd ε_{q}^{italicp}

where α is a material constant.…”

Section: Model Developmentmentioning

confidence: 99%

Simulating the effects of induced anisotropy on liquefaction potential using a new constitutive model

Tran

Wong

Dubujet

et al. 2013

Num Anal Meth Geomechanics

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The effects of induced anisotropy on the undrained behaviour of very loose and saturated sands have been a subject of intensive investigation, both experimentally and theoretically, by several authors in the past few years. This paper proposes an original constitutive model well-adapted to simulate the behaviour of sands subject to complex stress histories, in particular, the preloading cycle along the classical drained stress path in compression. The developed model belongs to the family of critical state models. Its construction is based on a few theoretical concepts taken from the theory of 'Bounding Surface Plasticity' developed among others by Y. Dafalias and Popov (1975), the 'Clay And Sand Model' (CASM) of H. Yu (2006), the CJS model (B. Cambou and K. Jafari (1988)) and the hyperelastic isotropic model of P. Lade (1987). To accurately simulate volume changes, which represent a key element in soil behaviour, a state-dependent dilatancy rule is proposed, which can account for the influences of stress and void ratio. The current void ratio depends implicitly on the irreversible strains already accumulated hence the strain history. A kinematic hardening is combined with an isotropic hardening, involving rotation and distortion of the bounding surface, in order to capture correctly the experimental observations. Comparisons of experimental results to numerical simulations show that the model is able to simulate with a good precision the major trends of undrained responses of loose and presheared sands. It predicts correctly rapid static liquefaction at small or null drained preloading, as well as the progressive transition to a completely stable behaviour typical of dense sands, while the sample is loose in reality. At intermediate to large amplitudes of preloadings, the model also predicts correctly the temporary stage of instability when the deviatoric stress decreases slightly before rising up again. Hardening modulus at current stress point. According to Bardet [49], the hardening modulus depends on the image stress point and the distance δ separating the later from the current stress point.

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d η = α \frac{1 + e}{λ - κ} {(\frac{p^{'}}{{italicp}_{a}})}^{- ψ} (\frac{s}{3 p^{'}}) Dd ε_{q}^{italicp}

where α is a material constant.…”

Section: Model Developmentmentioning

confidence: 99%

Simulating the effects of induced anisotropy on liquefaction potential using a new constitutive model

Tran

Wong

Dubujet

et al. 2013

Num Anal Meth Geomechanics

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“…Since modeling the full anisotropy of natural clay behavior is not practical due to the number of 30 parameters involved, efforts have been mainly focused on development of models with reduced number of 31 parameters while maintaining the capacity of the model [1]. Historically, for practical model development 32…”

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confidence: 99%

A viscoplastic SANICLAY model for natural soft soils

Rezania

Taiebat

Poletti

2016

Computers and Geotechnics

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8This paper focuses on constitutive and numerical modeling of strain-rate dependency in natural clays 9 while also accounting for anisotropy and destructuration. For this purpose the SANICLAY model that 10 accounts for the fabric anisotropy with the additional destructuration feature that accounts for sensitivity 11 of natural clays, is considered as the reference model. An associated flow rule is adopted for simplicity. 12The model formulation is refined to also account for the important feature of strain-rate dependency using 13 the Perzyna's overstress theory. The model is then implicitly integrated in finite element program 14 PLAXIS. Performance of the developed and implemented model is explored by comparing the simulation 15 results of several element tests and a boundary value problem to the available experimental data. The 16 element tests include the constant strain-rate under one-dimensional and triaxial conditions on different 17 clays. The boundary value problem includes a test embankment, namely embankment D constructed at 18 Saint Alban, Quebec. For comparison, the test embankment is also analysed using the Modified Cam-19 Clay (MCC) model, the SANICLAY model, and the viscoplastic model but without destructuration. 20 Results demonstrate the success of the developed and implemented viscoplastic SANICLAY in 21 reproducing the strain-rate dependent behavior of natural soft soils. 22 (M. Taiebat), elisapoletti@civil.uminho.pt (E. Poletti). 17]). Time-dependency is usually related to the soil viscosity that could lead to particular effects such as 52 creep, stress relaxation, and strain-rate dependency of response. Time-dependency of soil response can be 53 observed experimentally by means of creep tests, stress relaxation tests, or constant rate of strain (CRS) 54 tests [18]. Rate-sensitivity is a particular aspect of time effect that has been investigated extensively; it 55 3 influences both strength and stiffness of soils. Various studies using CRS tests have shown how faster 56 strain rates for a certain strain level lead to higher effective stresses; also, the general observation, 57 particularly in soft soils, is that higher undrained strengths can be achieved by increasing the loading rate 58 (e.g., [16][17][19][20]). The reported observations from laboratory studies all imply that consideration of soil 59 viscosity effects could be key for correct prediction of long term deformations in field conditions; although, 60 neglecting soil viscosity seemingly provide sufficiently correct predictions in short-term [21]. Landslides or 61 long-term deformations of tunnels and embankments on soft soils are examples of common practical 62 problems where a sustainable remediation and/or design solution can only be achieved if time-dependent 63 behavior of soil is taken into consideration. 64 In order to account for the time-dependency of soft clays' behavior, various frameworks can be found 65 in the literature. Among a number of popular frameworks such as the isotache theory of Šuklje [22] or the 66 non-sta...

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