scholarly journals Non linear elasto-plastic analysis of cylindrical cavity in rock mass using a Hoek-Brown criterion

2015 ◽  
Vol 68 (2) ◽  
pp. 145-152
Author(s):  
Jefferson Tales Simão ◽  
Christianne de Lyra Nogueira
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Cylindrical Cavity ◽  
Local Level ◽  
Consistency Condition ◽  
Linear Analysis ◽  
Perfectly Plastic ◽  
Computational Implementation ◽  
Non Linear ◽  
Elastic Perfectly Plastic

AbstractThis paper aims to present an elastic, perfectly plastic, constitutive model based on the Hoek-Brown failure criterion and with non-associative plasticity. The objective is to apply the model to the non-linear analysis of geotechnical problems like excavations in rock mass. The computational implementation was carried out with a computational program called ANLOG (Non-Linear Analysis of Geotechnical Problem) system based on a displacement formulation of the finite element method. Due to the non-linear nature of the constitutive model, the study adopts an incremental iterative Newton-Raphson procedure with automatic load increments to guarantee the global level equilibrium. In addition, to guarantee the consistency condition at the local level, the study adopts, for the stress integration, an explicit algorithm with automatic sub-increments of strain. To validate the computational implementation and applicability of the numerical model, the study uses theoretical results to compare with ones obtained with the numerical simulation of cylindrical cavity in rock mass.

Non-linear analysis of shallow cracks in smooth and notched plates Part 1: Analytical evaluation

2005 ◽  
Vol 40 (3) ◽  
pp. 237-244 ◽  
Author(s):  
G Härkegärd ◽  
A Wormsen
Keyword(s):  
Large Scale ◽  
Elastic Solid ◽  
Linear Analysis ◽  
Single Edge ◽  
Linear Elastic ◽  
Cracked Plate ◽  
Perfectly Plastic ◽  
Double Edge ◽  
Non Linear ◽  
Scale Yielding

This is the first paper of two that deal with the non-linear analysis of shallow cracks. Simple formulae are given for estimating the J integral for a power-hardening elastic-plastic solid. The proposed equation for estimating J makes use of the linear elastic and the fully plastic solution to interpolate over the entire range from small- to large-scale yielding. The elastic geometry factor is obtained by means of the stress intensity factor. In the fully plastic formulation, the plastic geometry factors are obtained by considering a pure power-hardening solid, which reduces at one limit to an incompressible linear elastic solid, and at the other to a perfectly plastic solid. The solutions are given for three basic configurations: a double-edge-cracked plate under tension and bending; a notched plate under tension with a crack at the root of the notch; a single-edge-cracked plate under bending. Both force control and displacement control are considered. The accuracy of the formulae is assessed using the finite element calculations in Part 2.

scholarly journals Strain-Softening Analyses of a Circular Bore under the Influence of Axial Stress

2021 ◽  
Vol 11 (17) ◽  
pp. 7937
Author(s):  
Xuechao Dong ◽  
Mingwei Guo ◽  
Shuilin Wang
Keyword(s):  
Rock Mass ◽  
Plane Stress ◽  
Strain Softening ◽  
Hydrostatic Stress ◽  
Axial Stress ◽  
Perfectly Plastic ◽  
Out Of Plane ◽  
Softening Process ◽  
Elastic Perfectly Plastic ◽  
Proper Consideration

Strain-softening analyses were performed around a circular bore in a Mohr–Coulomb rock mass subjected to a hydrostatic stress field in cross section and out-of-plane stress along the axis of the bore. Numerical procedures that simplify the strain-softening process in a step manner were employed, and on the basis of the theoretical solutions of the elastic–brittle–plastic(EBP) medium, the strain-softening results of the displacements, stresses and the plastic zones around the circular bore were obtained. The numerical solution was validated based on the fact that the strain-softening process became EBP when the softening slope was very steep and elastic-perfectly plastic(EP) when the softening slope was near zero. The results illustrated that the stresses and displacements in the rock mass surrounding the bore was affected by axial stress and that a proper consideration of out-of-plane stress is necessary. Moreover, the presented results can be used for the verification of numerical codes.

STRESS-STRAIN STATE PREDICTION SURROUNDING UNDERGROUND STRUCTURE, CONSTRUCTED IN NONLINEAR DEFORMED MEDIUM-SOFT SOILS

2020 ◽  
Vol 2 (1) ◽  
pp. 215-228
Author(s):  
A.G. PROTOSENYA ◽  
◽  
G.A. IOVLEV ◽  
Keyword(s):  
Strain State ◽  
Linear Models ◽  
Nonlinear Models ◽  
Underground Structure ◽  
Stress Strain ◽  
Soft Soils ◽  
Stress Strain State ◽  
Perfectly Plastic ◽  
Non Linear ◽  
Elastic Perfectly Plastic

Article proposes an approach for constructing a computational model for calculating the stress-strain state around tunnel, in medium soft soils. Set of deformations and strengths properties of which a given by elastic, elastic perfectly-plastic, and non-linear models. It founded, that with the input parameters used in model for elastic perfectly-plastic, and nonlinear models around tunnel formed yield surfaces. Analysis of the distinctions between elastic perfectly-plastic, and non-linear models was made. Was showed, that maximum deviatoric stress q is over-estimated in Mohr-Coulomb model. For hardening soil model was determined boundary of the plastic deformations.

Assessment of Compact Heat Exchanger Design Following Elastic Perfectly Plastic Methodology

2020 ◽  
Author(s):  
Avinash Shaw ◽  
Heramb P. Mahajan ◽  
Tasnim Hassan
Keyword(s):  
Global Analysis ◽  
Local Level ◽  
Primary Objective ◽  
Analysis Method ◽  
Perfectly Plastic ◽  
Heat Exchanger Design ◽  
Creep Fatigue ◽  
Asme Code ◽  
Computationally Intensive ◽  
Elastic Perfectly Plastic

Abstract Compact Heat Exchangers (CHXs) have a large number of miniature channels inside their core, which makes them highly thermal efficient and thus, prime utile for Next Generation Nuclear Plant (NGNP) applications. The fabrication of a CHX involves diffusion, brazed or welded bonding of plates to form CHX block with a channeled core. The elevated temperature and transient conditions of NGNP operation may induce excessive strain and creep-fatigue failure in channel ligaments. The primary objective of this study is to evaluate the design of CHX for application to NGNPs, following the ASME Code Elastic Perfectly Plastic (EPP) Analysis criteria in a draft ASME Code Section III, Division 5 and using the currently available Division 5 Code Cases (N-861 and N-862). As global analysis considering channels in the core is computationally intensive, a new analysis method is evaluated. In this method, the global analysis is performed by representing the channeled core by an elastic orthotropic material core. Subsequently, at the local level, EPP analysis is performed using models that include the channels, with thermal and pressure loading conditions. An ASME Draft Code Case is under development for the construction of CHXs. The analysis results are used to assess proposed stress limits and classification for load controlled stresses. For strain limits, the analysis results are evaluated using Code Cases N-861 and N-862 against the strain limit and creep-fatigue damage using the channel level submodel analysis. The applicability of the new analysis method, and use of the analysis results for evaluation against ASME proposed limits for various regions of the CHX are presented and discussed.

scholarly journals Seismic assessment of low ductile RC structures: buildings from before the modern seismic codes

2016 ◽  
Vol 33 (4) ◽  
pp. 1282-1307
Author(s):  
João Dias-Oliveira ◽  
H Rodrigues ◽  
Humberto Varum
Keyword(s):  
Local Level ◽  
Time History ◽  
Linear Analysis ◽  
Seismic Assessment ◽  
Seismic Safety ◽  
Content Type ◽  
Rc Structures ◽  
Infill Panels ◽  
Non Linear

Purpose – When a numerous amount of buildings was built in reinforced concrete, in a period when the regulations did not have the design philosophy for the occurrence of earthquakes, it is of extreme importance to carry out full and effective structural assessments, specially considering and comparing bare frame and infilled structure. The paper aims to discuss these issues. Design/methodology/approach – Among several possibilities to make the evaluation as, simplified, linear analysis and static non-linear analysis, the non-linear dynamic can provide the most accurate numerical behaviour compared to the real one. The time-history non-linear analyses are developed on the software SeismoStruct for different levels of intensity. Local verifications are then applied separately from both Eurocode and Italian Code. Findings – The application of validated models for the analysis of real buildings allows a complete seismic assessment. The level of uncertainty increases integrating particularities regarding the infill masonry walls. The paper shows important global and local seismic safety for these complex typology of buildings. Originality/value – A representative common concrete structure without seismic provisions is first analysed and discussed in terms of global behaviour, deformations and progression of forces. The case study structure is considered both as bare structure and with integrated infill panels. It is also discussed in a local level, about brittle and ductile mechanisms, and extra comparisons between different interpretations of different standards. The case study structure is considered both as bare structure and with integrated infill panels.

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