A new isotropic hyper-elasticity model for enhancing the rate of convergence of Mohr-Coulomb-like constitutive models and application to shallow foundations and trapdoors

Argani, L. P.; Gajo, Alessandro

doi:10.1016/j.compgeo.2020.103957

Cited by 5 publications

(5 citation statements)

References 28 publications

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“…In this work, we propose an innovative elastic strain energy function, which is inspired to the proposal by Argani and Gajo [2] for multiaxial stress states with the aim of improving the rate of convergence of Mohr-Coulomb models. For the sake of simplicity, we have assumed that the elastic properties do not depend on salt concentration, thus the elastic strain energy density function is proposed in the following form:…”

Section: Elastic Behaviourmentioning

confidence: 99%

A zero-thickness interface element incorporating hydro-chemo-mechanical coupling and rate-dependency

Ghalamzan Esfahani,

Gajo

2023

Acta Geotech.

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The interfaces play a key role in many engineering problems involving geologic materials. In particular, slope stability analyses of ancient landslides (that were subjected to large displacements along a slip surface) need the formulation of ad hoc interface elements. The mechanical response of slip surfaces in clays is affected by hydro-chemo-mechanical interactions and by rate effects and this paper presents the formulation of an innovative zero-thickness interface element for dealing with these kinds of effects. The proposed interface element is an extension of the modified zero-thickness element proposed by Goodman et al. (J Soil Mech Found Div ASCE 94:637–659, 1968). In addition to solid displacement, we consider the flow of water and the diffusion of a single salt in the fluid phase. Terzaghi’s effective stress principle is used leading to the usual hydro-mechanical coupling within the interface element. The fluxes of water and salt are considered in the longitudinal and in transversal directions of the interface element. For the constitutive relation, we propose an innovative nonlinear elastic energy that improves the numerical convergence in the occurrence of interface opening. The Mohr–Coulomb yield surface is used for the plastic regime in which we considered the effects of strain rate and salt concentration on the shearing behaviour of the interface element. The proposed element has been implemented in a user-defined subroutine of ABAQUS. The typical effects of salt concentration and displacement rate and the typical model responses for the longitudinal and transversal fluxes of salt and pore fluid are discussed in detail. Finally, the proposed interface element is validated through the comparison with experimental results.

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Section: Elastic Behaviourmentioning

confidence: 99%

A zero-thickness interface element incorporating hydro-chemo-mechanical coupling and rate-dependency

Ghalamzan Esfahani,

Gajo

2023

Acta Geotech.

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“…Formulated within a bounding-surface approach, the original model [22,23] can reproduce the stress-strain response of sands for a wide range of states with a single set of parameters. It relies on two surfaces: the strength surface and the yield surface, both defined through the Argyris et al [4] criterion. The size of the strength surface is defined as a fraction of the critical state surface through ratio r:…”

Section: Soil Constitutive Modelmentioning

confidence: 99%

“…Although equivalent to the original one, the version employed herein [20] is based on the framework of the classical kinematic-hardening plasticity, adopting a hyperelastic formulation to describe the soil behaviour inside the yield surface. Such formulation is modified as proposed by Argani and Gajo [4] to improve the rate of convergence for negligibly small confining pressures. At yielding, the magnitude of the plastic strain increment is related to the distance between the current stress state and an image stress state located on the strength surface through a hyperbolic relationship, based on constitutive parameter B.…”

Section: Soil Constitutive Modelmentioning

confidence: 99%

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Numerical modelling of the effects of foundation scour on the response of a bridge pier

et al. 2022

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Foundation scour can have a detrimental effect on the performance of bridge piers, inducing a significant reduction of the lateral capacity of the footing and accumulation of permanent settlement and rotation. Although the hydraulic processes responsible for foundation scour are nowadays well known, predicting their mechanical consequences is still challenging. Indeed, its impact on the failure mechanisms developing around the foundation has not been fully investigated. In this paper, numerical simulations are performed to study the vertical and lateral response of a scoured bridge pier founded on a cylindrical caisson foundation embedded in a layer of dense sand. The sand stress–strain behaviour is reproduced by employing the Severn-Trent model. The constitutive model is firstly calibrated on a set of soil element tests, including drained and undrained monotonic triaxial tests and resonant column tests. The calibration procedure is implemented considering the stress and strain nonuniformities within the samples, by simulating the laboratory tests as boundary value problems. The numerical model is then validated against the results of centrifuge tests. The results of the simulations are in good agreement with the experimental results in terms of foundation capacity and settlement accumulation. Moreover, the model can predict the effects of local and general scour. The numerical analyses also highlight the impact of scouring on the failure mechanisms, revealing that the soil resistance depends on the hydraulic scenario.

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“…In this investigation, the plate elements and spring elements were assumed to be elastic-plastic and linear elastic, respectively. The Mohr-Coulomb failure criterion was used for modelling the behaviour of soil and structural plane in this study, a technique widely utilized by scholars in nite element analysis(Ardakani et al, 2014;Argani and Gajo, 2021;Jia et al, 2010). Material properties of the slopes and rockbolts used in the numerical model were determined through laboratory testing, and are summarized in Table…”

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confidence: 99%

Anchorage mechanism of bamboo-steel composite rockbolts subjected to the coupled effect of tensile and shear stress

Ren

Huang

Wang

et al. 2023

Preprint

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Earthen heritage sites are of high cultural and scientific value. However, most of earthen heritage sites have been severely damaged and are in urgent need of repair. To address this issue, a novel rockbolt, bamboo-steel composite rockbolt (BSCR), has been proposed and widely employed in earthen site protection. However, research on the anchorage mechanism of BSCR lags behind engineering practice, particularly with regard to its behavior under the coupled effect of tensile and shear stress. In this study, combined with centrifugal test results, a numerical model was established and validated and a comparative analysis of the anchorage mechanism between conventional rockbolt (CR) and BSCR was also conducted. The results show that BSCR with a larger diameter and bending stiffness is superior to CR in protecting earthen heritage sites. Moreover, reducing the rockbolt inclination angle and increasing the number of rockbolt layers can mitigate slope deformation resulting from the coupled effect of tensile and shear stress. Increasing the length of BSCR can enhance the stability of bolted slopes; however, excessive extending the rockbolt length is inefficient due to the effect of the effective anchorage length of the rockbolt. These findings provide valuable insights into the use of BSCR in earthen site protection and may provide a reference for further research on its anchorage mechanism under complex stress conditions.

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A new isotropic hyper-elasticity model for enhancing the rate of convergence of Mohr-Coulomb-like constitutive models and application to shallow foundations and trapdoors

Cited by 5 publications

References 28 publications

A zero-thickness interface element incorporating hydro-chemo-mechanical coupling and rate-dependency

A zero-thickness interface element incorporating hydro-chemo-mechanical coupling and rate-dependency

Numerical modelling of the effects of foundation scour on the response of a bridge pier

Anchorage mechanism of bamboo-steel composite rockbolts subjected to the coupled effect of tensile and shear stress

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