scholarly journals Mechanical Behavior of Interface between Composite Geomembrane and Permeable Cushion Material

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Haimin Wu ◽  
Yiming Shu ◽  
Linjun Dai ◽  
Zhaoming Teng
Keyword(s):  
Three Dimensions ◽  
Deformation Analysis ◽  
Surface Barrier ◽  
Elastic Model ◽  
Lagrangian Analysis ◽  
Direct Shear Tests ◽  
Perfectly Plastic ◽  
Calculation Results ◽  
Elastic Perfectly Plastic ◽  
Nonlinear Elastic

An accurate description of composite geomembrane-cushion interface behavior is of great importance for stress-deformation analysis and stability assessment of geomembrane surface barrier of rock-fill dam. A series of direct shear tests were conducted to investigate the friction behaviors of interfaces between composite geomembrane and two different permeable cushion materials (crushed stones and polyurethane mixed crushed stones). The shear stress-displacement relationships of the two interfaces show different characteristics and were described by the nonlinear-elastic model and nonlinear-elastic perfectly plastic model, respectively. Then the two models were implemented into the Fast Lagrangian Analysis of Continua in Three Dimensions (FLAC3D) procedure correctly. By verification of a numerical example, numerical calculation results showed a good agreement with the theoretical solutions and test results.

scholarly journals Stress and Deformation Property of Geomembrane Surface Barrier for High Rock-fill Dam

2019 ◽  
Vol 275 ◽  
pp. 03003
Author(s):  
Haimin Wu ◽  
Zhen Zhang ◽  
Yiming Shu
Keyword(s):  
Peripheral Zone ◽  
Three Dimensions ◽  
Surface Barrier ◽  
Test Results ◽  
Rock Fill ◽  
Perfectly Plastic ◽  
Stress And Deformation ◽  
Elastic Perfectly Plastic ◽  
Material Nonlinear ◽  
Nonlinear Elastic

Based on the direct shear test results of interface between a composite geomembrane and cushion material, nonlinear elastic, perfectly plastic model was used to describe the interface behaviors. The interface model was incorporated into the Geogrid element of a fast Lagrange analysis of continua in three dimensions (FLAC3D) procedure through a user-defined program in the FISH. Then a geomembrane surfaced rock-fill dam on thick pervious foundation was numerically analyzed using the incorporated model. The numerical results showed that only small tension deformation can be found in the most area of geomembrane on the dam surface. However, large tension deformation of geomembrane appeared close to the anchorage in the peripheral zone of the barrier. The anchorage structure of geomembrane in this area should be carefully designed to avoid tension failure of geomembrane.

A Finite Element Study of Elasto-Plastic Hemispherical Contact

2003 ◽  
Author(s):  
Robert L. Jackson ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Constant Factor ◽  
Elastic Model ◽  
Asperity Contact ◽  
Finite Element Study ◽  
Perfectly Plastic ◽  
Wide Range ◽  
Elastic Perfectly Plastic ◽  
Element Study

This work presents a finite element study of elasto-plastic hemispherical contact. The results are normalized such that they are valid for macro contacts (e.g., rolling element bearings) and micro contacts (e.g., asperity contact). The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic case (known as the Abbott and Firestone model) and the perfectly elastic case (known as the Hertz contact). At the same interference, the area of contact is shown to be larger for the elasto-plastic model than that of the elastic model. It is also shown, that at the same interference, the load carrying capacity of the elasto-plastic modeled sphere is less than that for the Hertzian solution. This work finds that the fully plastic average contact pressure, or hardness, commonly approximated to be a constant factor (about three) times the yield strength, actually varies with the deformed contact geometry, which in turn is dependant upon the material properties (e.g., yield strength). The results are fit by empirical formulations for a wide range of interferences and materials for use in other applications.

Mohr-Coulomb Model Considering Variation of Elastic Modulus and Its Application

2006 ◽  
Vol 306-308 ◽  
pp. 1445-1448 ◽  
Author(s):  
X.Z. Cui ◽  
Q. Jin ◽  
Q.S. Shang ◽  
S.T. Liu
Keyword(s):  
Elastic Modulus ◽  
Compressive Stress ◽  
Strain Curve ◽  
Material Strength ◽  
Elastic Model ◽  
Lagrangian Analysis ◽  
Stress Strain Curve ◽  
Modified Model ◽  
Coulomb Model ◽  
Nonlinear Elastic

Mohr-Coulomb model is a perfect elastoplastic model. It only considers the variation of material strength with lateral compressive stress, but doesn’t consider the variation of elastic modulus with lateral compressive stress and stress level and this is accordant with the true characteristic of geological material. The elasticity modulus in Mohr-Coulomb model was modified by employing the processing method of tangential modulus in Duncan-Chang nonlinear elastic model. In modified model, the stress-strain curve in elastic phrase behaves as hyperbola. In order to embed the modified model in FLAC3D program (Fast Lagrangian Analysis of Continua in 3 Dimensions), a preprocessing program was written and was employed to analyze numerically the bearing capacity of rigid piles loaded laterally.

The Method of Design by Analysis for Cylindrical Pressure Vessels with Spherically Dished Head

2019 ◽  
Vol 795 ◽  
pp. 262-267
Author(s):  
Zhen Yu Wang ◽  
Jian Wu ◽  
Ming De Xue ◽  
Shi Yu Li
Keyword(s):  
Internal Pressure ◽  
Shell Theory ◽  
Pressure Vessels ◽  
Design Criteria ◽  
Analysis Method ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Nonlinear Elastic ◽  
Theoretical Stress ◽  
Thin Shell Theory

Standards GB 150.3-2011 and JB4732-1995 (Confirmed in 2005) provide design methods for the cylindrical pressure vessels with spherically dished head under internal pressure. It is available for the ratio of the internal pressure p to the allowable stress Sm, p/Sm≥0.002. Engineers desire the design curves for p/Sm<0.002. This paper presents a stress analysis method based on elastic thin shell theory for a spherically dished head jointed to the end or the middle of the cylindrical shell. The design criteria in the current standards are modified. Based on the theoretical stress solution and design criteria, the suitable range of the design curves is extended to p/Sm≥0.001. Nonlinear elastic perfectly-plastic finite element method ensures the reliability of the design curves.

scholarly journals Numerical simulation of hillside mine waste dump construction

2012 ◽  
Vol 65 (4) ◽  
pp. 553-559 ◽  
Author(s):  
Marcílio Baltazar Teixeira ◽  
Christianne de Lyra Nogueira ◽  
Waldyr Lopes de Oliveira Filho
Keyword(s):  
Numerical Simulation ◽  
Mine Waste ◽  
Waste Dump ◽  
The Finite Element Method ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Geometric Configurations ◽  
Mine Waste Dump ◽  
Elastic Perfectly Plastic ◽  
Nonlinear Elastic

In activities involving disposal of mine waste in a dump, it is necessary to carry out a preliminary study of the mechanical behavior of both dump and the foundation materials. Due to the complexity of this problem, numerical techniques are essential for providing an approximate answer to the problem. Thus, the finite element method (FEM) was used to evaluate the stress-strain-strength behavior of a hillside waste dump built on a deformable foundation by the ascending method; the results of which are herein presented. The dump material is considered to be Morh-Coulomb nonlinear elastic perfectly plastic while the foundation material is considered to be linear elastic. The numerical simulation of mine waste dump construction is carried out by the "gravity turn on" technique and the dynamic mesh procedure. Different geometric configurations are analyzed and it is concluded that some requirements established by law should be reviewed and refined.

scholarly journals A FEM analysis of the settlement of a tall building situated on loess subsoil

2020 ◽  
Vol 10 (1) ◽  
pp. 519-526
Author(s):  
Krzysztof Nepelski
Keyword(s):  
Fem Analysis ◽  
Actual Process ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Modified Cam Clay ◽  
Linear Behaviour ◽  
Subsequent Calculation ◽  
Elastic Perfectly Plastic ◽  
Subsoil Model ◽  
Storey Building

AbstractIn order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

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