scholarly journals Parameters of Sand-Tyre Chips Mixture for Hardening Soil Small Constitutive Model

2021 ◽  
Vol 1203 (2) ◽  
pp. 022067
Author(s):  
Magdalena Kowalska
Keyword(s):  
Constitutive Models ◽  
Small Strain ◽  
Bender Elements ◽  
Empirical Formulas ◽  
Anthropogenic Soils ◽  
Material Parameters ◽  
Compression Stiffness ◽  
Strain Relationship ◽  
Soil Behaviour ◽  
Hardening Soil Model

Abstract Hardening Soil model with the small strain extension (HSS) is lately one of the most popular constitutive models to describe soil behaviour. It is versatile – includes the phenomena of shear strength, stress history, dilatancy, volumetric and shear hardening, hyperbolic stress-strain relationship in axial compression, stiffness dependency on stress and its degradation with strain, as well as the regain of the high stiffness after sharp loading reversals. Even though the model is advanced and complex, accordingly to its authors, it is relatively easy to calibrate based on results of standard tests and empirical formulas. In this paper an attempt was undertaken to estimate the parameters of untypical anthropogenic soils – mixtures of sand and scrap tyre rubber in order to build a database for future numerical analyses. A literature review was conducted and, eventually, the material parameters were determined based on results of a series of laboratory tests (cyclic and monotonic triaxial with bender elements, direct shear) published by researchers of Wollongong University of Australia.

scholarly journals The small strain stiffness from bender elements tests for clayey soils

2018 ◽  
Vol 50 (4) ◽  
pp. 353-371
Author(s):  
Katarzyna Markowska-Lech ◽  
Wojciech Sas ◽  
Mariusz Lech ◽  
Katarzyna Gabryś ◽  
Alojzy Szymański
Keyword(s):  
Field Tests ◽  
Small Strain ◽  
Test Results ◽  
Bender Elements ◽  
Element Analysis ◽  
Factors Affecting ◽  
Small Strain Stiffness ◽  
Seismic Wave Velocities ◽  
Case Basis ◽  
Hardening Soil Model

Abstract The shear modulus of soils at small strain (G0) is one of the input parameters in a finite element analysis with the hardening soil model with small strain stiffness, required in the advanced numerical analyses of geotechnical engineering problems. The small strain stiffness can be determined based on the seismic wave velocities measured in the laboratory and field tests, but the interpretation of test results is still under discussion because of many different factors affecting the measurements of the wave travel time. The recommendations and proposed solutions found in the literature are helpful as a guide, but ought to be adopted with a certain measure of care and caution on a case-by-case basis. The equipment, procedures, tests results and interpretation analyses of bender elements (BE) tests performed on natural overconsolidated cohesive soils are presented.

scholarly journals Enhancing Constitutive Models for Soils: Adding the Capability to Model Nonlinear Small Strain in Shear

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
S. Seyedan ◽  
W. T. Sołowski
Keyword(s):  
Yield Surface ◽  
Constitutive Models ◽  
Strain Range ◽  
Small Strain ◽  
Deviatoric Stress ◽  
Triaxial Tests ◽  
Engineering Practice ◽  
Model Parameters ◽  
Highly Nonlinear ◽  
Strain Relationship

The deviatoric stress-deviatoric strain relationship in soils is highly nonlinear, especially in the small strain range. However, the constitutive models which aim to replicate the small strain nonlinearity are often complex and rarely used in geotechnical engineering practice. The goal of this study is to offer a simple way for updating the existing constitutive models, widely used in geotechnical practice, to take into account the small strain shear modulus changes. The study uses an existing small strain relationship to derive a yield surface. When the yield surface is introduced to an existing soil model, it enhances the model with the nonlinear deviatoric stress-deviatoric strain relationship in the small strain range. The paper also gives an example of such a model enhancement by combining the new yield surface with the Modified Cam Clay constitutive model. The validation simulations of the undrained triaxial tests on London Clay and Ham River sand with the upgraded constitutive models replicate the experiments clearly better than the base models, without any changes to existing model parameters and the core source code associated with the base model.

scholarly journals The influence of the soil constitutive models on the seismic analysis of pile-supported wharf structures with batter piles in cut-slope rock dike

2020 ◽  
Vol 42 (3) ◽  
pp. 191-209
Author(s):  
Lylia Deghoul ◽  
Smail Gabi ◽  
Adam Hamrouni
Keyword(s):  
Constitutive Models ◽  
Small Strain ◽  
Loose Sand ◽  
Cut Slope ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Soil Constitutive Models ◽  
Elastic Perfectly Plastic ◽  
Batter Piles ◽  
Hardening Soil Model

AbstractIn coastal regions, earthquakes caused severe damage to marine structures. Many researchers have conducted numerical investigations in order to understand the dynamic behavior of these structures. The most frequently used model in numerical calculations of soil is the linear-elastic perfectly plastic model with a Mohr-Coulomb failure criterion (MC model). It is recommended to use this model to represent a first-order approximation of soil behavior. Therefore, it is necessary to accommodate soil constitutive models for the specific geotechnical problems.In this paper, three soil constitutive models with different accuracy were applied by using the two-dimensional finite element software PLAXIS to study the behavior of pile-supported wharf embedded in rock dike, under the 1989 Loma Prieta earthquake. These models are: a linear-elastic perfectly plastic model (MC model), an elastoplastic model with isotropic hardening (HS model), and the Hardening Soil model with an extension to the small-strain stiffness (HSS model).A typical pile-supported wharf structure with batter piles from the western United States ports was selected to perform the study. The wharf included cut-slope (sliver) rock dike configuration, which is constituted by a thin layer of rockfill overlaid by a slope of loose sand. The foundation soil and the backfill soil behind the wharf were all dense sand. The soil parameters used in the study were calibrated in numerical soil element tests (Oedometer and Triaxial tests).The wharf displacement and pore pressure results obtained using models with different accuracy were compared to the numerical results of Heidary-Torkamani et al.[28] It was found that the Hardening Soil model with small-strain stiffness (HSS model) gives clearly better results than the MC and HS models.Afterwards, the pile displacements in sloping rockfill were analyzed. The displacement time histories of the rock dike at the top and at the toe were also exposed. It can be noted that during the earthquake there was a significant lateral ground displacement at the upper part of the embankment due to the liquefaction of loose sand. This movement caused displacement at the dike top greater than its displacement at the toe. Consequently, the behavior of the wharf was affected and the pile displacements were important, specially the piles closest to the dike top.

A New Nonlinear Stress-Strain Model for Soils at Various Strain Levels

2013 ◽  
Vol 631-632 ◽  
pp. 782-788
Author(s):  
Cheng Chen ◽  
Zheng Ming Zhou
Keyword(s):  
Compression Test ◽  
Triaxial Compression ◽  
Small Strain ◽  
Empirical Formulas ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Proposed Model ◽  
Nonlinear Stress ◽  
London Clay ◽  
Strain Model

Soils have nonlinear stiffness and develops irrecoverable strains even at very small strain levels. Accurate modeling of stress-strain behaviour at various strain levels is very important for predicting the deformation of soils. Some existing stress-strain models are reviewed and evaluated firstly. And then a new simple non-linear stress-strain model is proposed. Four undetermined parameters involved in the proposed model can be obtained through maximum Young’s module, deformation module, and limit deviator stress and linearity index of soils that can be measured from experiment directly or calculated by empirical formulas indirectly. The effectiveness of the proposed stress-strain model is examined by predicting stress-strain curves measured in plane-strain compression test on Toyota sand and undrained triaxial compression test on London clay. The fitting results of the proposed model are in good agreement with experimental data, which verify the effectiveness of the model.

Uncertainty Quantification in Predicting Behaviour of Rubber-Like Materials in Uni-Axial Loading

2020 ◽  
Author(s):  
Aref Ghaderi ◽  
Vahid Morovati ◽  
Pouyan Nasiri ◽  
Roozbeh Dargazany
Keyword(s):  
Uncertainty Quantification ◽  
Mechanical Response ◽  
Pure Shear ◽  
Constitutive Models ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Deterministic Models ◽  
Data Set ◽  
Material Parameters ◽  
Axial Extension

Abstract Material parameters related to deterministic models can have different values due to variation of experiments outcome. From a mathematical point of view, probabilistic modeling can improve this problem. It means that material parameters of constitutive models can be characterized as random variables with a probability distribution. To this end, we propose a constitutive models of rubber-like materials based on uncertainty quantification (UQ) approach. UQ reduces uncertainties in both computational and real-world applications. Constitutive models in elastomers play a crucial role in both science and industry due to their unique hyper-elastic behavior under different loading conditions (uni-axial extension, biaxial, or pure shear). Here our goal is to model the uncertainty in constitutive models of elastomers, and accordingly, identify sensitive parameters that we highly contribute to model uncertainty and error. Modern UQ models can be implemented to use the physics of the problem compared to black-box machine learning approaches that uses data only. In this research, we propagate uncertainty through the model, characterize sensitivity of material behavior to show the importance of each parameter for uncertainty reduction. To this end, we utilized Bayesian rules to develop a model considering uncertainty in the mechanical response of elastomers. As an important assumption, we believe that our measurements are around the model prediction, but it is contaminated by Gaussian noise. We can make the noise by maximizing the posterior. The uni-axial extension experimental data set is used to calibrate the model and propagate uncertainty in this research.

scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

A New Elasto-Plastic Critical State Model RU+MCC for Overconsolidated Soil

2016 ◽  
Vol 837 ◽  
pp. 68-74
Author(s):  
Rafal Uliniarz
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Small Strain ◽  
Computer Code ◽  
Constitutive Law ◽  
Isotropic Hardening ◽  
Loading Test ◽  
Modified Cam Clay ◽  
Soil Behaviour ◽  
Cam Clay

The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

scholarly journals Finite element modelling of an energy-geomembrane underground pumped hydroelectric energy storage system

2020 ◽  
Vol 205 ◽  
pp. 07001
Author(s):  
Hans Henning Stutz ◽  
Peter Norlyk ◽  
Kenneth Sørensen ◽  
Lars Vabbersgaard Andersen ◽  
Kenny Kataoka Sørensen ◽  
...  
Keyword(s):  
Finite Element ◽  
Energy Storage ◽  
Storage System ◽  
Constitutive Models ◽  
Energy System ◽  
Energy Storage System ◽  
Elastic Model ◽  
Hydroelectric Energy ◽  
Linear Elastic ◽  
Soil Behaviour

The increasing need for energy storage technology has led to a massive interest in novel energy storage methods. The energy geomembrane system is such a novel energy storage method. The concept of the system is briefly introduced, and a holistic numerical model of the system is presented. The model uses advanced finite-element techniques to model the energy storage system using fluid cavity elements. The developed geomembrane energy system is modelled with different constitutive models to represent the soil behaviour: a linear elastic model, a nonlinear Mohr-Coulomb model, and a hypoplastic constitutive model. The consequences of these different models on the results are studied. Hereby, the focus is the first inflation and deflation cycle of the system.

scholarly journals Identification of orthotropic material parameters for acute, necrotic, fibrotic and remodelling myocardial infarcts in the rat

2019 ◽  
Author(s):  
Mazin S. Sirry ◽  
Laura Dubuis ◽  
Neil H. Davies ◽  
Jun Liao ◽  
Thomas Franz
Keyword(s):  
Constitutive Model ◽  
Orthotropic Material ◽  
Constitutive Models ◽  
Biaxial Stress ◽  
Percentage Error ◽  
Fe Model ◽  
Stress Strain ◽  
Material Parameters ◽  
Strain Data ◽  
Tensile Experiment

AbstractFinite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models

2018 ◽  
Vol 89 (8) ◽  
pp. 1472-1487
Author(s):  
Krzysztof Zerdzicki ◽  
Pawel Klosowski ◽  
Krzysztof Woznica
Keyword(s):  
Polyvinyl Chloride ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Material Models ◽  
Material Parameters ◽  
Coated Fabric ◽  
Coated Fabrics ◽  
Term Creep

In this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have been conducted: uniaxial tensile, biaxial tensile and long-term creep tests. The obtained results have been used for the parameter identification of the piecewise non-linear, Burgers and Bodner–Partom models. Next, the analysis of the influence of environmental conditions on the parameters of these models has been made. It has been concluded that some parameters are more and the others are less sensitive to the exposure to environmental and mechanical conditions. The change of material parameters for fill threads (due to larger deformation) is higher. The obtained results may be useful in the durability evaluation of the textile membranes reinforced with polyester threads and PVC coated. All the constitutive models with the identified parameters may be used for the numerical analysis of structures made of fabrics at the service beginning and after long-term usage.

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