Finite element analyses of steep man-made cuts in Dublin boulder clay

2008 ◽  
Vol 45 (4) ◽  
pp. 549-559 ◽  
Author(s):  
N. Kovacevic ◽  
G. W.E. Miligan ◽  
C. O. Menkiti ◽  
M. Long ◽  
D. M. Potts
Keyword(s):  
Finite Element ◽  
Low Permeability ◽  
Time To Failure ◽  
Finite Element Analyses ◽  
Short Term ◽  
Pore Water Pressures ◽  
Boulder Clay ◽  
The Stability ◽  
Steep Slopes ◽  
Insight Into

This paper describes finite element analyses undertaken to gain an insight into the short-term behaviour of temporary steep slopes in Dublin boulder clay for cut and cover sections of the recently completed Dublin Port Tunnel. The analyses of two steep slopes are reported: (i) an unsupported slope for a full-scale trial excavation and (ii) a partly nailed slope for a prototype cut and cover structure. It has been found that a major contribution to the stability of these cuts is an increase in the effective stress (and thus strength) due to both (i) depressed pore-water pressures (suctions) and (ii) a tendency of the Dublin boulder clay to dilate during undrained excavation in this low permeability and very dense material. However, the presence of even thin, discontinuous but recharged granular lenses of a higher permeability significantly reduces the time to failure.

scholarly journals Finite element modeling of nanoindentation on an elastic-plastic microsphere

2020 ◽  
Author(s):  
Jialian Chen ◽  
Hongzhou Li
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Computational Study ◽  
Theoretical Method ◽  
Finite Element Analyses ◽  
Structured Materials ◽  
Elastic Plastic ◽  
Element Simulation ◽  
Insight Into

Abstract The understanding of the mechanical indentation on a curved specimen (e.g., microspheres and microfibers) is of paramount importance in the characterization of curved micro-structured materials, but there has been no reliable theoretical method to evaluate the mechanical behavior of nanoindentation on a microsphere. This article reports a computational study on the instrumented nanoindentation of elastic-plastic microsphere materials via finite element simulation. The finite element analyses indicate that all loading curves are parabolic curves and the loading curve for different materials can be calculated from one single indentation. The results demonstrate that the Oliver-Pharr formula is unsuitable for calculating the elastic modulus of nanoindentation involving cured surfaces. The surface of the test specimen of a microsphere requires prepolishing to achieve accurate results of indentation on a micro-spherical material. This study provides new insight into the establishment of nanoindentation models that can effectively be used to simulate the mechanical behavior of a microsphere.

Significance of Finite Compliance of a Cracked Piping System on Fracture Integrity Assessment

2005 ◽  
Author(s):  
I. A. Khan ◽  
V. Bhasin ◽  
K. K. Vaze ◽  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Finite Element ◽  
Driving Force ◽  
Piping System ◽  
Combined Effects ◽  
Finite Element Analyses ◽  
Crack Driving Force ◽  
Integrity Assessment ◽  
Linear Elastic ◽  
The Stability ◽  
Integrity Analysis

One of the thrust areas in the integrity analysis of cracked nuclear piping system is concern with the reduction in moment, at the crack section due to combined effects of local and global residual compliance. However an important consideration in the design of piping system, which is generally not considered, is the re-distribution of load that occurs due to finite compliance of the piping system. The load at the crack section reduces while it increases generally at support/anchor locations, which may be high stressed locations. In case of stiff-piping system this re-distribution of load may be quite significant. Hence for the complete integrity of the piping system these un-cracked locations should also be re-assessed. A generalized procedure is suggested to take care of the reduction in load at the cracked section and corresponding increase in reactions at the support/anchor locations in a 3-D cracked piping system. Thus the stability of cracked section as well as other highly stressed locations can be simultaneously assessed. Here it is assumed that the remaining piping system behaves in a linear elastic manner and the plasticity remains confined to the cracked section only. Detailed finite element analyses are performed on circuitous (3-D) cracked piping system to validate the developed approach. Results presented in this article clearly show that due to reduction in moment the crack driving force, for the same external load, reduces significantly.

An approximate method for estimating the stability of geotextile-reinforced embankments

1985 ◽  
Vol 22 (3) ◽  
pp. 392-398 ◽  
Author(s):  
R. K. Rowe ◽  
K. L. Soderman
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Limit Equilibrium ◽  
Soft Clay ◽  
Soil Reinforcement ◽  
Short Term ◽  
Critical Height ◽  
Reinforced Embankments ◽  
The Stability ◽  
Conventional Limit

A method of estimating the short-term stability of reinforced embankments constructed on a deposit that can be idealized as being uniform and purely cohesive is described. This approach maintains the simplicity of conventional limit equilibrium techniques while incorporating the effect of soil–geotextile interaction in terms of an allowable compatible strain for the geotextile. This allowable compatible strain may be deduced from a design chart and depends on the foundation stiffness, the embankment geometry, the depth of the deposit, and the critical height of an unreinforced embankment. The procedure is checked against finite element results and against one published case history. Key words: embankment, geotextile, analysis, limit equilibrium, finite element, soft clay, shear strength, soil reinforcement.

Effect of Preloading on the Response of a Shallow Skirted Foundation

2014 ◽  
Author(s):  
Cristina Vulpe ◽  
Susan Gourvenec
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Small Strain ◽  
Significant Gain ◽  
Finite Element Analyses ◽  
Foundation Design ◽  
Degree Of Consolidation ◽  
Insight Into

The effect of preloading on the vertical settlement and bearing capacity of a circular skirted foundation was investigated as a function of relative preload and degree of consolidation by means of small strain finite element analyses. Significant gain in bearing capacity was observed for practical levels of preloads and duration of consolidation, offering an insight into potential efficiencies in foundation design.

Remarks on the stability of temporary cuts

1990 ◽  
Vol 27 (5) ◽  
pp. 687-692 ◽  
Author(s):  
S. Leroueil ◽  
P. La Rochelle ◽  
F. Tavenas ◽  
M. Roy
Keyword(s):  
Undrained Shear Strength ◽  
Short Term ◽  
Overconsolidation Ratio ◽  
Term Stability ◽  
Long Term Stability ◽  
Liquidity Index ◽  
The Stability ◽  
Insight Into ◽  
Undrained Shear

A re-analysis of the observations and data related to the stability of excavations in clays gives a new insight into the problem. It is shown that for clays with a liquidity index greater than 0.4, the short-term stability can be estimated on the basis of the undrained shear strength without applying any correction factor; it is also shown that the long-term stability is lower than the short-term stability by an amount that depends on the overconsolidation ratio of the clay. Finally, experience proving that pore-pressure equilibration is highly variable and difficult to predict, it is recommended to systematically instrument excavations with piezometers. Key words: clay, short-term stability, long-term stability, excavations, pore pressures, overconsolidation ratio.

Stability of a Suppression Method of Dent and Spring-Back in Zigzag Bending of Sheet Metal/Plate

2016 ◽  
Vol 716 ◽  
pp. 931-940 ◽  
Author(s):  
Takashi Kuboki ◽  
Takuma Yamada ◽  
Shohei Kajikawa ◽  
Hiroyuki Abe
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Vertical Movement ◽  
Metal Plate ◽  
Finite Element Analyses ◽  
Spring Back ◽  
Special Shape ◽  
Suppression Method ◽  
The Stability ◽  
Zigzag Shape

This paper focuses upon zigzag-shape bending for suppression of defects, including dent and springback. A series of finite element analyses was carried out in order to optimize the bending condition for suppression of these defects. As a result, it was clarified that a diagonal movement of the upper die was effective for suppression of dents while a rather vertical movement of the upper die was effective for suppression of springback. In order to suppress dent and springback at the same time, this paper proposes another method of bending method, whereby the upper die with special shape moves in a diagonal way. Moreover, the stability of the method against variation of tool dead position, which would be caused by elastic deformation of supporting members, was studied by FEM, followed by experimental verification.

scholarly journals Modeling the Mechanical Behavior of the Jaws and Their Related Structures By Finite Element (Fe) Analysis

1997 ◽  
Vol 8 (1) ◽  
pp. 90-104 ◽  
Author(s):  
T.W.P. Korioth ◽  
A. Versluis
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Materials Science ◽  
Three Dimensional ◽  
Stress Fields ◽  
Sensitivity Analyses ◽  
Finite Element Models ◽  
Finite Element Analyses ◽  
Relevant Variables ◽  
Insight Into

In this paper, we provide a review of mechanical finite element analyses applied to the maxillary and/or mandibular bone with their associated natural and restored structures. It includes a description of the principles and the relevant variables involved, and their critical application to published finite element models ranging from three-dimensional reconstructions of the jaws to detailed investigations on the behavior of natural and restored teeth, as well as basic materials science. The survey revealed that many outstanding FE approaches related to natural and restored dental structures had already been done 10-20 years ago. Several three-dimensional mandibular models are currently available, but a more realistic correlation with physiological chewing and biting tasks is needed. Many FE models lack experimentally derived material properties, sensitivity analyses, or validation attempts, and yield too much significance to their predictive, quantitative outcome. A combination of direct validation and, most importantly, the complete assessment of methodical changes in all relevant variables involved in the modeled system probably indicates a good FE modeling approach. A numerical method for addressing mechanical problems is a powerful contemporary research tool. FE analyses can provide precise insight into the complex mechanical behavior of natural and restored craniofacial structures affected by three-dimensional stress fields which are still very difficult to assess otherwise.

A Bird in the Hand Isn’t Good for Long

2018 ◽  
Vol 65 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Stefan Scherbaum ◽  
Simon Frisch ◽  
Maja Dshemuchadse
Keyword(s):  
Decision Making ◽  
Cognitive Control ◽  
The Other ◽  
Decision Task ◽  
Short Term ◽  
Additional Time ◽  
Control Processes ◽  
Folk Wisdom ◽  
Study Participants ◽  
Insight Into

Abstract. Folk wisdom tells us that additional time to make a decision helps us to refrain from the first impulse to take the bird in the hand. However, the question why the time to decide plays an important role is still unanswered. Here we distinguish two explanations, one based on a bias in value accumulation that has to be overcome with time, the other based on cognitive control processes that need time to set in. In an intertemporal decision task, we use mouse tracking to study participants’ responses to options’ values and delays which were presented sequentially. We find that the information about options’ delays does indeed lead to an immediate bias that is controlled afterwards, matching the prediction of control processes needed to counter initial impulses. Hence, by using a dynamic measure, we provide insight into the processes underlying short-term oriented choices in intertemporal decision making.

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