New Approach for Predicting the Long-Term Behavior of Bentonite: The Unified Method of Molecular Dynamics and Homogenization Analysis

1997 ◽  
Vol 506 ◽  
Author(s):  
K. Kawamura ◽  
Y. Ichikawa ◽  
M. Nakano ◽  
K. Kitayama ◽  
H. Kawamura
Keyword(s):  
Molecular Dynamics ◽  
Molecular Model ◽  
New Approach ◽  
Method Of Molecular Dynamics ◽  
Bulk Scale ◽  
Long Term Behavior ◽  
The Unified Method ◽  
Dynamics Method ◽  
Unified Method

ABSTRACTFor predicting the long-term behavior of bentonite, we present a new and unified simulation procedure of Molecular Dynamics Method (MD) and Homogenization Analysis (HA). The MD is applied to establish molecular-scale bentonite properties and the HA is introduced to extrapolate the molecular model to the bulk-scale continuum model.

Investigation of the Dynamic Behavior of Railway Ballast Using Molecular Dynamics Simulations

2001 ◽  
Author(s):  
Holger Kruse ◽  
Karl Popp
Keyword(s):  
Molecular Dynamics ◽  
Initial Conditions ◽  
Contact Forces ◽  
Contact Network ◽  
Railway Ballast ◽  
Particle Layer ◽  
Dynamics Simulations ◽  
Long Term Behavior ◽  
Overlap Area

Abstract The molecular dynamics method (MD method) is a powerful tool for the investigation of granular materials like the railway ballast. The characteristics of this method are explained in detail. In contrast to a continuum description, each single stone of the ballast is taken into account. Since the ballast settlement is strongly influenced by the shape of the stones, in the two-dimensional model polygonal particles are used. These particles are surrounded by fixed boundary walls. At the top of the ballast particle layer, a single sleeper is positioned which is loaded by forces occurring at the real track. The contact forces are calculated from the overlap area of the particle geometries. The paper includes information about the sensitivity of the model behavior on initial conditions and contact law parameters. Furthermore, the contact network, the quasi-static stiffness of the ballast layer and its long-term behavior are addressed. Particular emphasis is put on the description of current difficulties and challenges in applying the MD method.

Evaluation of Long-term behavior of bentonite buffer based on Molecular Dynamics and Homogenization Analysis

2004 ◽  
Vol 2004.9 (0) ◽  
pp. 477-480
Author(s):  
Kenichi NAKAOKA ◽  
Hideki KAWAMURA ◽  
Yasuaki ICHIKAWA ◽  
Katsuuki KAWAMURA ◽  
Noriyuki SAITO
Keyword(s):  
Molecular Dynamics ◽  
Bentonite Buffer ◽  
Long Term Behavior

Failure of a Test Embankment On a Sensitive Champlain Clay Deposit

1974 ◽  
Vol 11 (1) ◽  
pp. 142-164 ◽  
Author(s):  
P. La Rochelle ◽  
B. Trak ◽  
F. Tavenas ◽  
M. Roy
Keyword(s):  
Research Program ◽  
Factor Of Safety ◽  
Soft Clay ◽  
New Approach ◽  
Short And Long Term ◽  
Undrained Strength ◽  
The Stability ◽  
Long Term Behavior ◽  
Test Embankment

The present paper reports on the failure of a test embankment built on a soft, sensitive, and cemented clay in Saint-Alban, Quebec. The embankment was built as a first stage of a research program aimed at studying the short and long term behavior of embankments on soft clay foundations.A complete description of the embankment, of the instrumentation, and of the failure is given, followed by the analysis of the failure performed on the basis of different assumptions of fill behavior and of vane strength values mobilized in the clay crust. The analyses show that the assumptions of full mobilization of friction in the fill seems to be the most representative of the fill behavior in the present case and that a suitable factor of safety is obtained only when a reduction of vane strength is assumed to act in the crust.A new approach based on the residual undrained strength is suggested and seems to offer some potential as a valuable means of analyzing the stability of embankments on clay foundations.

Study on the Effect of Different Factors of Displacement Cascades in Alpha-Fe by Molecular Dynamics Simulations

2020 ◽  
Author(s):  
Pandong Lin ◽  
Junfeng Nie ◽  
Meidan Liu
Keyword(s):  
Molecular Dynamics ◽  
Tensile Strain ◽  
Vacancy Concentration ◽  
Irradiation Damage ◽  
Effect Of Temperature ◽  
Displacement Cascade ◽  
Rpv Steel ◽  
Dynamics Simulations ◽  
Dynamics Method

Abstract As the key component of RPV steel, α-Fe is under neutron irradiation during its long-term service, and lattice atoms of α-Fe are knocked by neutrons, which leads to irradiation damage. In this paper, molecular dynamics method is conducted to investigate the effect of temperature, vacancy concentration and tensile strain on irradiation-induced damage by displacement cascade simulations in α-Fe. The simulations are performed with primary knock-on atom energies ranging from 0.1 to 5 keV, temperature ranging from 100 to 500K, vacancy concentration ranging from 0% to 1% and applied tensile strain ranging from 0 to 5%. The time evolution of defects produced during displacement cascade can be obtained where the surviving number of Frenkel pairs increases rapidly at first, then decrease and comes to stability finally. The influence of these factors on defect production can be concluded as following: The increase of PKA energy, vacancy concentration and applied tensile strain can lead to the increase of defect numbers. In contrast, the increase of temperature decreases the defect numbers. Vacancies and interstitials cluster size distributions are varied in different case. The results are meaningful to describe some microcosmic mechanisms of RPV steels in nuclear system.

scholarly journals SIMULATION OF TRANSPORT PHENOMENA OF FULLERENES IN THE FLUID BY METHOD OF MOLECULAR DYNAMICS

2017 ◽  
Vol 17 (5) ◽  
pp. 93-103
Author(s):  
E.D. Gayduk ◽  
V.A. Saleev
Keyword(s):  
Molecular Dynamics ◽  
Solid Particle ◽  
Effective Potential ◽  
Transport Phenomena ◽  
Molecular Dynamics Method ◽  
Classical Molecular Dynamics ◽  
Method Of Molecular Dynamics ◽  
Dynamics Method

In the frameworks of classical molecular dynamics method the coefficients ofdiffusion and viscosity of fullerenes in fluid (benzol) depending on the temperature of nanosuspension have been calculated.The effective potential of fullerenemolecule interaction used in calculations is obtained under the assumption ofadditivity of fullerene and fluid molecules interaction, where fullerene is considered as a solid particle.

Reduction of major amputations in the diabetic ischaemic foot: A strategy to "take control" with conservative care as well as revascularisation

VASA ◽  
2001 ◽  
Vol 30 (Supplement 58) ◽  
pp. 6-14 ◽  
Author(s):  
Edmonds ◽  
Foster
Keyword(s):  
Natural History ◽  
Treatment Plan ◽  
Staging System ◽  
Vascular Control ◽  
New Approach ◽  
Conservative Care ◽  
Arterial Bypass ◽  
Therapeutic Footwear ◽  
Frequent Problem

The diabetic ischaemic foot has become an increasingly frequent problem over the last decade. However, we report a new approach consisting of a basic classification, a simple staging system of the natural history and a treatment plan for each stage, within a multi-disciplinary framework. This approach of "taking control" consists of two parts: 1. long-term conservative care including debridement of ulcers (to obtain wound control), eradication of sepsis (micribiological control), and provision of therapeutic footwear (mechanical control), and 2. revascularisation by angioplasty and arterial bypass (vascular control). This approach has led to a 50% reduction in the rate of major amputations in patients attending with ischaemic ulceration and absent foot pulses from 1989 to 1999 (from 4.6% to 2.3% per year). Patients who underwent angioplasty increased from 6% to 13%. Arterial bypass similarly increased from 3% to 7% of cases. However, even with an increased rate of revascularisation, 80% of patients responded to conservative care alone. This,we conclude, is an essential part of the management of all patients with ischaemic feet.

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