Anisotropic Modeling of Granular Bases in Flexible Pavements

1997 ◽  
Vol 1577 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Erol Tutumluer ◽  
Marshall R. Thompson
Keyword(s):  
Flexible Pavements ◽  
Triaxial Tests ◽  
Anisotropic Model ◽  
Wheel Load ◽  
Finite Element Program ◽  
Linear Elastic ◽  
Element Program ◽  
Stress Dependent ◽  
Repeated Load Triaxial ◽  
Simple Stress

A new cross-anisotropic model is proposed to predict the performance of granular bases in flexible pavements. A cross-anisotropic representation has different material properties (i.e., elastic modulus and Poisson’s ratio) assigned in the horizontal and vertical directions. Repeated-load triaxial tests with vertical and lateral deformation measurements can be used to establish these anisotropic properties. Simple stress-dependent granular material models, obtained from analysis of the laboratory test data, are used in a nonlinear finite element program, named GT-PAVE, to predict pavement responses. The horizontal and shear stiffnesses are typically found to be less than the vertical. The nonlinear anisotropic approach is shown to account effectively for the dilative behavior observed under the wheel load and the effects of compaction-induced residual stresses. The main advantage of using a cross-anisotropic model in the base is the drastic reduction or elimination of significant tensile stresses generally predicted by isotropic linear elastic layered programs.

scholarly journals Study of the mechanical behaviour of reclaimed asphalt aggregates without binder addition

2019 ◽  
Vol 92 ◽  
pp. 10004
Author(s):  
Laura Gaillard ◽  
Cyrille Chazallon ◽  
Pierre Hornych ◽  
Juan Carlos Quezada
Keyword(s):  
Triaxial Tests ◽  
Reclaimed Asphalt ◽  
Failure Resistance ◽  
Linear Elastic ◽  
Repeated Load ◽  
C 50 ◽  
Stress Dependent ◽  
Repeated Load Triaxial ◽  
Different Levels ◽  
Temperature Test

The objective of this paper is to investigate a source of reclaimed asphalt aggregates without binder addition. To this end, a series of triaxial tests was performed. First, monotonic triaxial tests allowed to determine failure resistance of the material at 20°C, 50°C and at 20°C with a prior preheating at 50°C. Then, the resilient and permanent behaviours at 20°C were studied thanks to Repeated Load Triaxial (RLT) tests with different levels of loading. The results show that increasing the temperature test implies a drop of failure resistance but a higher cohesion. RLT tests reveal a stress dependent resilient behaviour. Finally, the experimental results were compared with calibrations of the non-linear elastic Boyce model.

A Material Model for Prediction of Fatigue Damage and Degradation of CFRP Materials

2017 ◽  
Vol 742 ◽  
pp. 740-744 ◽  
Author(s):  
Jörg Hohe ◽  
Monika Gall ◽  
Hannes Gauch ◽  
Sascha Fliegener ◽  
Zalkha Murni binti Abdul Hamid
Keyword(s):  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Material Model ◽  
Finite Element Program ◽  
Damage Evolution Equation ◽  
Brittle Damage ◽  
Linear Elastic ◽  
Element Program ◽  
Definition Of

Objective of the present study is the definition of a material model accounting for fatigue damage and degradation. The model is formulated as a brittle damage model in the otherwise linear elastic framework. A stress driven damage evolution equation is derived from microplasticity considerations. The model is implemented as a user-defined material model into a commercial finite element program. In a comparison with experimental data in the low cycle fatigue regime, a good agreement with the numerical prediction is obtained.

scholarly journals The Bearing Capacity of Circular Footings in Sand: Comparison between Model Tests and Numerical Simulations Based on a Nonlinear Mohr Failure Envelope

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Sven Krabbenhoft ◽  
Johan Clausen ◽  
Lars Damkilde
Keyword(s):  
Bearing Capacity ◽  
Yield Criterion ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Test Results ◽  
Finite Element Program ◽  
Model Foundation ◽  
Element Program ◽  
Confining Pressures ◽  
Good Agreement

This paper presents the results of a series of triaxial tests with dry sand at confining pressures varying from 1.5 kPa to 100 kPa at relative densities of 0.20, 0.59, and 0.84. The results, which are in reasonable accordance with an equation given by Bolton, show that the friction angle is strongly dependent on the stress level and on the basis of the test results, a nonlinear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100 mm, has been conducted. Comparisons have been made with results from 1g model scale tests with a foundation of similar size and a good agreement between numerical results and test results has been found.

scholarly journals Evaluating geomechanical effects related to the production of a Brazilian reservoir

2021 ◽  
Vol 11 (6) ◽  
pp. 2661-2678
Author(s):  
Raquel Oliveira Lima ◽  
Leonardo José do Nascimento Guimarães ◽  
Leonardo Cabral Pereira
Keyword(s):  
Finite Element ◽  
Oil Recovery ◽  
Computational Effort ◽  
Absolute Permeability ◽  
Coupling Scheme ◽  
Reservoir Properties ◽  
Finite Element Program ◽  
Element Program ◽  
Stress Dependent ◽  
The Impact

AbstractThis paper presents a coupled finite element approach for modeling geomechanical effects induced by production/injection processes in petroleum reservoirs. The module developed employs coupled- reservoir analysis using CMG IMEX® as the flow simulator and a finite element program in MATLAB® as the stress–strain simulator, in a two-way explicit partial coupling scheme. The flow and mechanical problems are coupled by the change of effective stress due to the change in pore pressure and by varying stress-dependent reservoir properties, such as pore compressibility, absolute permeability, and porosity. The coupling procedure was applied to the Namorado Field (Campos Basin, Brazil) to quantify the impact of the rock deformation on fluid recovery. Based on the cases studied, the coupled analyses predicted higher oil recovery than the conventional reservoir simulations. The results showed that the reservoir deformation can affect its performance and must be taken into account in reservoir-engineering studies depending on production strategy and reservoir stiffness. Besides, the geomechanical calculations were performed only in the coupling timesteps, reducing the computational effort and making this coupling method feasible on a field scale.

Analysis of Ultimate Load-Bearing Capacity of Long-Span CFST Arch Bridges

2011 ◽  
Vol 90-93 ◽  
pp. 1149-1156 ◽  
Author(s):  
Yang Liu ◽  
Da Wang ◽  
Yi Zhou Zhu
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Ultimate Load ◽  
Elastic Buckling ◽  
Load Bearing Capacity ◽  
Finite Element Program ◽  
Load Bearing ◽  
Linear Elastic ◽  
Long Span ◽  
Element Program

In order to study the ultimate load-bearing capacity of the long-span concrete-filled steel tubular (CFST) arch bridge with fly-bird-type, the ANSYS finite element program was used to establish its special model, and to study ultimate load-bearing capacity of this bridge with three different methods. The constitutive relation factors of concrete-filled steel tubular was taken into consideration including confining effect ultimate load coefficients, failure modes, and load-displacement curves of this bridge under different cases. The result indicate that the ultimate load-bearing capacity of the bridge can meet the requirement, all of its failure modes is out-plane, the two methods, linear elastic buckling analysis and only geometric nonlinearity analysis, will over high estimate ultimate load-bearing capacity of this bridge, and linear elastic buckling method cannot reflect real failure mode of this structure. In order to correctly estimate the ultimate load-bearing capacity of the bridge structure, the effect of geometric and material double nonlinearity couldn’t be neglected.

A Method to Calculate Pack Ice Driving Forces

1995 ◽  
Vol 117 (2) ◽  
pp. 145-150
Author(s):  
E. Evgin ◽  
C. Zhan ◽  
R. M. W. Frederking
Keyword(s):  
Driving Forces ◽  
Stress Distributions ◽  
Nonlinear Analyses ◽  
Creep Equation ◽  
Finite Element Program ◽  
Linear Elastic ◽  
Pack Ice ◽  
Short Period ◽  
Stress Levels ◽  
Element Program

A method is proposed to calculate pack ice driving forces. In order to develop the method, stress distributions in a circular ice floe are calculated for various boundary loading conditions. The analysis is carried out using a special-purpose finite element program in which Sinha’s creep equation is used to model the behavior of ice. Charts relating pack ice driving forces to stresses in the ice floe are produced for both linear elastic and creep equations for ice behavior. The results indicate that, for a short period of loading time and at low stress levels, a linear elastic analysis can be used to calculate the pack ice driving forces. However, when the stress levels in the ice floe are high or the time span of load application is long, linear and nonlinear analyses produce much different values for pack ice driving forces.

Stress Singularity at the Free Surface of a Dynamically Growing Crack

1990 ◽  
Vol 57 (1) ◽  
pp. 112-116 ◽  
Author(s):  
Peter Gudmundson ◽  
So¨ren O¨stlund
Keyword(s):  
Free Surface ◽  
Crack Front ◽  
Isotropic Material ◽  
Stress Singularity ◽  
Crack Tip ◽  
Finite Element Program ◽  
Linear Elastic ◽  
Growing Crack ◽  
Element Program ◽  
Tip Velocity

The stress singularity at the intersection between the crack front and the free surface of a dynamically growing crack in a linear elastic isotropic material has been numerically evaluated by an especially developed finite element program. The singularity parameter (λ), defined by σ ~ Rλ−1, is presented as a function of the crack-tip velocity and the angle (β) between the crack front and the free surface. The angle (β) at which the singularity (λ) equals 0.5 was found to be 101 deg almost independently of the crack-tip velocity.

scholarly journals Application of Fracture Mechanics to Cracking Problems in Soils

2014 ◽  
Vol 8 (1) ◽  
pp. 1-8 ◽  
Author(s):  
G. Juárez-Luna ◽  
G. Ayala
Keyword(s):  
Fracture Mechanics ◽  
Numerical Models ◽  
Practical Interest ◽  
Critical Stress Intensity Factor ◽  
Critical Conditions ◽  
Finite Element Program ◽  
Linear Elastic ◽  
Element Program ◽  
Elastic Fracture ◽  
Geotechnical Studies

This paper analyzes the problem of fracture in soils using the linear elastic fracture mechanics theory. Six cases of practical interest are investigated where the soil is subjected to different critical conditions that may produce cracks. To model the phenomenon of crack propagation, a two-dimensional fracture mechanics finite element program is used. In all cases, the properties of clays in the Valley of Mexico was used. The self-weight of the soil is considered as the main cause of geostatic stresses in the medium. Based on results from previous studies, the value of the critical stress intensity factor is calculated and validated. It is assumed that, only mode I fracture occurs. The crack depths obtained with the numerical models are congruent with the field data of existing geotechnical studies in the Valley of Mexico.

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