A finite deformation multiplicative plasticity model with non–local hardening for bonded geomaterials

Oliynyk, Kateryna; Ciantia, Matteo Oryem; Tamagnini, Claudio

doi:10.1016/j.compgeo.2021.104209

Cited by 19 publications

(13 citation statements)

References 83 publications

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“…The FD_Milan model is a non-associative, isotropic hardening finite-deformation plasticity model for structured soils and weak rocks, developed by Oliynyk et al (2021) based on the multiplicative decomposition of the deformation gradient and on the adoption of a suitable free energy function to describe the elastic response of the material. Its evolution equations in the spatial setting are briefly summarized here: subjected to the Kuhn-Tucker complementarity conditions: r In the above equations, τ and τ are the Kirchhoff stress and its Jaumann objective rate; d is the rate of deformation tensor; d p is the plastic rate of deform ation tensor; a e is the spatial hyperelastic tangent stiffness of the material; γ _ is the plastic multiplier; f and g are the yield function and the plastic potential, respectively (see Oliynyk et al 2021 for details); P s and P t are internal variables; the functions are the plastic volumetric and deviatoric rates of deformation; and ρ , ξ s , and are material s ρ t ξ t constants.…”

Section: Local Versionmentioning

confidence: 99%

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PFEM modeling of CPTu tests in saturated structured soils

Oliynyk¹,

Ciantia²,

Tamagnini³

2022

Cone Penetration Testing 2022

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The conventional interpretation of CPTu tests is typically based on empirical and semi-empirical correlations based on very crude descriptions of soil behavior, such as the total stress approach coupled with the Terzaghi-Rendulic pseudo-3d consolidation theory for modeling the time evolution of excess pore water pressure. The aim of this work is to show that a more rational interpretation of the coupled deformation and flow processes occurring in the soil during a CPTu test is possible by resorting to the numerical solution of the relevant governing equations, incorporating a realistic constitutive model for the soil. In order to deal with the large displacements and deformations induced by the cone penetration, the Particle Finite Element Method code G-PFEM, recently developed for geomechanical applications, has been used for this purpose. A key feature of the present work is the use of a finite deformation version of a non-associative isotropic hardening plasticity model for structured geoma terials -the FD_Milan model. The model is equipped with a structure-related internal variable which provide a macroscopic description of the effects of structure in natural, fine-grained soils. In order to deal with strain local ization, typically observed in structured geomaterials upon yielding, the model has been equipped with a non-local version of the hardening laws, which has demonstrated capable of regularizing the pathological mesh dependence of classical FE solutions in the post-localization regime. A number of PFEM simulations of CPTu tests on a soft structured natural clay has been performed in order to assess the effects of the initial bond strength and permeabil ity on the predicted results of the test, as well as on the spatial distributions of accumulated plastic strains, internal variables and excess pore water pressures. The results obtained represent a promising step towards a more rational interpretation of the CPTu tests in structured geomaterials and for their use in the calibration of advanced soil models.

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Section: Local Versionmentioning

confidence: 99%

“…The Table 1. Sets of material constants adopted in the CPTu test simulations (see Oliynyk et al 2021 for details on the meaning of each constant).…”

Section: Simulation Programmentioning

confidence: 99%

PFEM modeling of CPTu tests in saturated structured soils

Oliynyk¹,

Ciantia²,

Tamagnini³

2022

Cone Penetration Testing 2022

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“…Since then several constitute models developed based on this original approach. For example, [7] showed the C-CASM to model cemented clays whilst more recently [8,9] showed how a large strain formulation of a similar models can be used to simulate CPT in structured clays and soft rocks respectively. In this work the cemented clay and sand model (C-CASM) fully described in [4] is used.…”

Section: The Constitutive Modelmentioning

confidence: 99%

Application of a bonded critical state model to design tunnel support for rockmass bulking

Ciantia

Arroyo

Kaiser

2021

IOP Conf. Ser.: Earth Environ. Sci.

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Gabion-type support is a favoured option to restrain bulking in pillar walls of mine footprint tunnels. It uses closely spaced short reinforcements in tunnel walls (typically fully grouted rebar) in combination with surface support (rock fragment retention systems such as shotcrete, weld wire mesh, straps, etc.). The system is installed while the rock is still mostly intact and is conceived to maintain support capacity even when, the rock attains a fully fragmented state, acting then like a gabion or earth-reinforced type retaining wall. In this paper the interaction between the support system and the highly stressed pillar walls is investigated numerically by means of finite element analyses within the framework of displacement-based design. Because the material response should capture the passage from intact rock to fully fragmented state, an advanced elasto-plastic bonded constitutive model was adopted as a simulation framework. The model is calibrated to replicate the mechanical behaviour of Bursnip Sandstone and Amarelo Pais Granite. These two rocks were selected because of high quality triaxial tests results from the literature. After showing the good performance of the model to reproduce both low and high pressure triaxial compression behaviour an extensive parametric study investigating the effects of bolt types on gabion response is presented.

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“…On the other hand, amongst various continuum approaches, the Geotechnical Particle Finite Element Method (GPFEM) has recently been shown to be able to manage large deformations and address the complexities of nonlinear soil behaviour [10], [11]. GPFEM has shown to be suitable to investigate CPT installation and interpretation in various soil types [11]- [13].…”

Section: Introductionmentioning

confidence: 99%

Comparison of continuum (PFEM) and discrete (DEM) approaches for large insertion BVPs in soft rocks

Zheng,

Previtali,

Ciantia

et al. 2023

VIII International Conference on Particle-Based Methods

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In recent years, significant advancements in computational efficiency have enabled the application of advanced numerical models to solve boundary value problems (BVPs) in geotechnics, including those related to large-displacement problems. However, challenging problems, such as those involving open-ended piles (OEs) in soft rocks, require specialized approaches due to material and geometrical non linearities combined to the large deformation soil-structure interaction. This paper presents a comparison of two approaches for modeling OE pile installation in soft rocks. The first approach employs the Discrete Element Method (DEM), which represents the rock as separate particles bonded together, and introduces a new contact model for highly porous rocks. The second approach uses the Geotechnical Particle Finite Element Method (GPFEM) and investigates the coupled hydromechanical effects during pile installation using a robust and mesh-independent implementation of an elastic-plastic constitutive model at large strains. The DEM approach explores the micromechanical features of pile plugging and unveils the mechanisms behind radial stress distributions inside and outside the plug. The study highlights the strengths and limitations of each modeling approach, providing insights into the behavior of OE piles in soft rocks.

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A finite deformation multiplicative plasticity model with non–local hardening for bonded geomaterials

Cited by 19 publications

References 83 publications

PFEM modeling of CPTu tests in saturated structured soils

PFEM modeling of CPTu tests in saturated structured soils

Application of a bonded critical state model to design tunnel support for rockmass bulking

Comparison of continuum (PFEM) and discrete (DEM) approaches for large insertion BVPs in soft rocks

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