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Article
Publication date: 5 February 2018

Namal Yapage and Samanthika Liyanapathirana

This paper aims to investigate the behaviour of geosynthetic reinforced deep cement mixed (DCM) column-supported embankments constructed over soft soils.

257

Abstract

Purpose

This paper aims to investigate the behaviour of geosynthetic reinforced deep cement mixed (DCM) column-supported embankments constructed over soft soils.

Design/methodology/approach

Coupled consolidation analyses based on the finite element method are carried out assuming that the soil and DCM columns are fully saturated porous mediums. In the first part of the paper, a case study of an embankment constructed over a very soft soil deposit in Finland is presented. Two- and three-dimensional finite element models for the case study are developed including isolated and attached DCM columns beneath the embankment to capture the arching mechanism between DCM columns. The model simulations were carried out considering the actual staged construction procedure adopted in the field. Finite element predictions show good agreement with field data and confirm that the load transfer is mainly between attached columns beneath the embankment. Next, the significance of geosynthetic reinforcement on the load transfer mechanism is investigated. Finally, the influence of permeability of columns and soft soil on the performance of geosynthetic reinforcement column-supported embankments is studied.

Findings

Results demonstrate that the excess pore pressure dissipation rate is fast in DCM column-improved ground compared to the same case without any columns, although the same permeability is assigned to both DCM columns and surrounding soft soil. When DCM column permeability exceeds soil permeability, excess pore pressure dissipation rate shows a remarkable increase compared to that observed when the DCM column permeability is less than or equal to the permeability of surrounding soft soil. [ ]

Originality/value

This paper investigates the contribution of permeability and geosynthetic layer on the vertical load transfer mechanism of the embankment and modelling issues related to application of the embankment load and the properties of the cement-improved columns.

Details

Journal of Engineering, Design and Technology, vol. 16 no. 1
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 1 May 2000

D.S. Liyanapathirana, A.J. Deeks and M.F. Randolph

In finite element analysis of pile driving, the nodes of the finite element mesh are the most important locations for output stresses. Especially at the pile‐soil interface, it is…

1040

Abstract

In finite element analysis of pile driving, the nodes of the finite element mesh are the most important locations for output stresses. Especially at the pile‐soil interface, it is essential to obtain accurate nodal stresses. Several global and local stress smoothing methods available in the literature were reviewed and examined. Global methods are found to be computationally expensive, so results obtained from several local stress smoothing methods are compared. It is shown that accurate nodal stresses can be obtained by approximating the stress distribution inside four‐element patches by a polynomial with order equal to the order of the shape functions. Equally good results can be obtained by approximating the stress distribution inside each element by a bilinear surface. When a method taking into account both equilibrium and boundary conditions was applied, a set of ill‐conditioned matrices was produced for the four‐element patches. Such methods are therefore not recommended.

Details

Engineering Computations, vol. 17 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 January 2013

N.N.S. Yapage and D.S. Liyanapathirana

Several constitutive models are available in the literature to describe the mechanical behaviour of cement stabilized soils. However, difficulties in implementing such models…

867

Abstract

Purpose

Several constitutive models are available in the literature to describe the mechanical behaviour of cement stabilized soils. However, difficulties in implementing such models within commercial finite element programs have hindered their application to solve related boundary value problems. Therefore, the aim of this study is to implement a constitutive model, which has the capability to simulate cement stabilized soil behaviour, into the finite element program ABAQUS through the user material subroutine UMAT.

Design/methodology/approach

After a detailed review of existing constitutive models for cement stabilized soils, a model based on the elasto‐plastic theory and the extended critical state concept with an associated flow rule is selected for the finite element implementation. A semi‐implicit integration method (cutting plane algorithm) with a continuum elasto‐plastic modulus and path dependent stress prediction strategy has been used in the implementation. The performance of the new finite element formulation of the constitutive model is verified by simulating triaxial test data using the finite element program with the new implementation and predictions from constitutive equations as well as experimental data.

Findings

The paper provides the implementation procedure of the constitutive model into ABAQUS but this method is useful for the implementation of any other constitutive model into ABAQUS or any other finite element program. Simulated results for the volumetric deformation of cement stabilized soils show that the cement stabilized soils do not obey the associated flow rule at high confining pressures. The parametric study shows that the influence of cementation increases the brittle nature and the bearing capacity of treated clay. In addition the results show that proposed finite element implementation has the ability to illustrate key features of the cement stabilized clay.

Originality/value

This paper presents an implementation of an elasto‐plastic constitutive model, based on the extended critical state concept, for cement stabilized soils into a finite element programme, which has been identified as an important and challenging topic in computational geomechanics. This implementation is useful in solving boundary value problems in geomechanics involving cement stabilized soils, incorporating key characteristics of these soils.

Details

Engineering Computations, vol. 30 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 5 July 2021

Tamir Amari and Mohamed Nabil Houhou

This paper aims to investigate single pile and pile group responses due to deep braced excavation-induced soil movement in soft clay overlying dense sand. The analysis focuses…

166

Abstract

Purpose

This paper aims to investigate single pile and pile group responses due to deep braced excavation-induced soil movement in soft clay overlying dense sand. The analysis focuses first on the response of vertical single pile in terms of induced bending moment, lateral deflection, induced axial force, skin resistance distribution and pile settlement. To better understand the single pile behaviour, a parametric study was carried out. To provide further insights about the response of pile group system, different pile group configurations were considered.

Design/methodology/approach

Using the explicit finite element code PLAXIS 3 D, a full three-dimensional numerical analysis is carried out to investigate pile responses when performing an adjacent deep braced excavation. The numerical model was validated based on the results of a centrifuge test. The relevance of the 3 D model is also judged by comparison with the 2 D plane strain model using the PLAXIS 2 D code.

Findings

The results obtained allowed a thorough understanding of the pile response and the soil–pile–structure interactions phenomenon. The findings reveal that the deep excavation may cause appreciable bending moments, lateral deflections and axial forces in nearby piles. The parametric study showed that the pile responses are strongly influenced by the excavation depth, relative pile location, sand density, excavation support system and pile length. It also showed that the response of a pile within a group depends on its location in relation to the other piles of the pile group, its distance from the retaining wall and the number of piles in the group.

Originality/value

Unlike previous studies which investigated the problem in homogeneous geological context (sand or clay), in this paper, the pile response was thoroughly studied in a multi-layered soil using 3 D numerical simulation. To take into account the small-strain nonlinear behaviour of the soil, the Hardening soil model with small-strain stiffness was used in this analysis. For a preliminary design, this numerical study can serve as a practical basis for similar projects.

Details

World Journal of Engineering, vol. 19 no. 6
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 6 July 2015

Sanka Dilshan Ekanayake, D.S. Liyanapathirana and Chin Jian Leo

EPS geofoam has been widely used in embankment construction, slope stabilisation, retaining walls, bridge approaches and abutments. Nevertheless, the potential of EPS geofoam as…

398

Abstract

Purpose

EPS geofoam has been widely used in embankment construction, slope stabilisation, retaining walls, bridge approaches and abutments. Nevertheless, the potential of EPS geofoam as an engineering material in geotechnical applications has not been fully realised yet. The purpose of this paper is to present the finite element formulation of a constitutive model based on the hardening plasticity, which has the ability to simulate short-term behaviour of EPS geofoam, to predict the mechanical behaviour of EPS geofoam and it is implemented in the finite element programme ABAQUS.

Design/methodology/approach

Finite element formulation is presented based on the explicit integration scheme.

Findings

The finite element formulation is verified using triaxial test data found in the literature (Wong and Leo, 2006 and Chun et al., 2004) for two varieties of EPS geofoam. Performance of the constitute model is compared with four other models found in the literature and results confirm that the constitutive model used in this study has the ability to simulate the short-term EPS geofoam behaviour with sufficient accuracy.

Research limitations/implications

This research is focused only on the short-term behaviour of EPS geofoam. Experimental studies will be carried out in future to incorporate effects of temperature and creep on the material behaviour.

Practical implications

This formulation will be applicable to finite element analysis of boundary value problems involving EPS geofoam (e.g. application of EPS geofoam in ground vibration isolation, retaining structures as compressible inclusions and stabilisation of slopes).

Originality/value

Finite element analysis of EPS geofoam applications are available in the literature using elastic perfectly plastic constitutive models. However, this is the first paper presenting a finite element application utilising a constitutive model specifically developed for EPS geofoam.

Details

Engineering Computations, vol. 32 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 5 July 2024

Ying Wang, Chaojie Wang, Zhenhua Hu, Yonghui Chen and Bo Min

The soft stabilized slab and pile-supported (SSPS) embankment is an improvement technique to increase the efficiency of resources in road construction. To capture the effects of…

59

Abstract

Purpose

The soft stabilized slab and pile-supported (SSPS) embankment is an improvement technique to increase the efficiency of resources in road construction. To capture the effects of stabilized slabs on the stress transfer mechanism, the differential settlements and the lateral displacement of the embankment completely. A theoretical model of SSPS is proposed by considering the effect of soil arching and the interaction between the embankment fill, stabilized soil, pile, foundation soil and bearing stratum.

Design/methodology/approach

In the theoretical model, the stress and strain coordination relationship of the system was analyzed in view of the minimum potential energy theory and equal settlement plane theory. Subsequently, the theoretical method was applied to field tests for comparison. Finally, the influence of the elastic modulus and the thickness of the stabilized slab on the stress concentration ratio and foundation settlement were examined.

Findings

In addition to the experimental findings, the method has been revealed to be reasonable and feasible, considering its ability to effectively exploit the stabilized slab effect and improve the bearing capacity of soil and piles. An economical and reasonable arrangement scheme for the thickness and strength of stabilized slabs was obtained. The results reveal that the optimum elastic modulus was chosen as 28 MPa–60 MPa, and the optimum thickness of the stabilized slab was selected as 1.5 m–2.1 m using the parameters of field tests, which can provide guidance to engineering design.

Originality/value

An optimization calculation method is established to analyze the load transfer mechanics of the SSPS embankment based on a double-equal settlement plane. The model’s rationality was analyzed by comparing the settlement and stress concentration ratios in the field tests. Subsequently, the influence of the elastic modulus and the thickness of the stabilized slab on the stress concentration ratio and settlement were examined. An economical and reasonable arrangement scheme for the thickness and elastic modulus of stabilized slabs was obtained, which can provide a novel approach for engineering design.

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Article
Publication date: 9 October 2019

Hui Chen and Donghai Liu

The purpose of this study is to develop a stochastic finite element method (FEM) to solve the calculation precision deficiency caused by spatial variability of dam compaction…

329

Abstract

Purpose

The purpose of this study is to develop a stochastic finite element method (FEM) to solve the calculation precision deficiency caused by spatial variability of dam compaction quality.

Design/methodology/approach

The Choleski decomposition method was applied to generate constraint random field of porosity. Large-scale laboratory triaxial tests were conducted to determine the quantitative relationship between the dam compaction quality and Duncan–Chang constitutive model parameters. Based on this developed relationship, the constraint random fields of the mechanical parameters were generated. The stochastic FEM could be conducted.

Findings

When the fully random field was simulated without the restriction effect of experimental data on test pits, the spatial variabilities of both displacement and stress results were all overestimated; however, when the stochastic FEM was performed disregarding the correlation between mechanical parameters, the variabilities of vertical displacement and stress results were underestimated and variation pattern for horizontal displacement also changed. In addition, the method could produce results that are closer to the actual situation.

Practical implications

Although only concrete-faced rockfill dam was tested in the numerical examples, the proposed method is applicable for arbitrary types of rockfill dams.

Originality/value

The value of this study is that the proposed method allowed for the spatial variability of constitutive model parameters and that the applicability was confirmed by the actual project.

Details

Engineering Computations, vol. 36 no. 9
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 12 February 2024

Nirupika Liyanapathirana and Mary Low

This study aims to examine the determinants of ethical decision-making (EDM) of professional accountants in Sri Lanka, drawing on Rest’s (1986) four-component EDM model. The level…

236

Abstract

Purpose

This study aims to examine the determinants of ethical decision-making (EDM) of professional accountants in Sri Lanka, drawing on Rest’s (1986) four-component EDM model. The level of corporate collapses and fraud, coupled with the high level of corruption in Sri Lanka, has highlighted the importance and the timely nature of this research in the EDM processes of Sri Lankan accountants.

Design/methodology/approach

Data was collected from a sample of 315 accountants through a questionnaire survey that included four written ethical vignettes and was analysed using partial least square-structural equation modelling techniques.

Findings

The findings revealed a significant relationship between ethical awareness and ethical judgement, providing support for Rest’s model. However, the study does not support Rest’s model on the direct relationship between ethical judgement and ethical intention. Intrinsic religiosity and moral intensity significantly influenced the ethical awareness of accountants. Several determinants including accountants’ age, education, intrinsic religiosity, organisational ethical culture, familiarity with the professional ethical code and moral intensity influenced ethical judgement. However, the findings did not report any significant relationships between the study’s variables and ethical intention.

Originality/value

The study adds to the existing literature by providing a bigger picture of how various determinants work together in one EDM model and demonstrating that the EDM of accountants is multifaceted. The new finding on an insignificant relationship between ethical judgement and ethical intention implies that the Rest’s EDM process may be mediated and moderated by other constraints blocking accountants’ intention to act due to various pressures in a corrupt society, Sri Lanka, where accountants operate.

Details

Journal of Accounting & Organizational Change, vol. 20 no. 5
Type: Research Article
ISSN: 1832-5912

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Article
Publication date: 17 October 2022

Nirupika Liyanapathirana and Chris Akroyd

This paper aims to understand how accountants in Sri Lanka perceive the effect of religiosity on ethical decision-making. Sri Lanka is a highly religious country, but it also has…

666

Abstract

Purpose

This paper aims to understand how accountants in Sri Lanka perceive the effect of religiosity on ethical decision-making. Sri Lanka is a highly religious country, but it also has a high level of corruption, so understanding ethical decision-making in this context is important for the accounting profession.

Design/methodology/approach

Data were collected using semi-structured interviews with 40 accountants in Sri Lanka with decision-making roles. Virtue ethics theory and content analysis were used to analyse the interview data and categorise accountants' responses into themes using an interpretive methodology.

Findings

This paper identifies three ways in which religiosity can influence accountants’ ethical decision-making. Firstly, through a faith in the beliefs of their religion; secondly, through awareness of religious prescriptions and virtues; and thirdly, through a commitment towards religious practices and rituals. However, the findings show that religiosity does not always influence the ethical decision-making of accountants because of pervasive corruption, which is a cultural norm in contemporary Sri Lanka. Thus, it is evident that there is an interrelationship between religious and cultural environments which can influence ethical decision-making.

Originality/value

While the religiosity of accountants can support ethical decision-making, the findings of this paper show that the cultural norm of corruption can mediate this connection as the evidence shows that accountants with a strong religious background, irrespective of their religion, may still act unethically when corruption is a cultural norm.

Details

Pacific Accounting Review, vol. 35 no. 2
Type: Research Article
ISSN: 0114-0582

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Article
Publication date: 13 August 2024

Ishwara P. and Naod Mekonnen

The purpose of this study is to examine the influence of moral intensity on the ethical decision-making process of professional accountants based on a combined…

114

Abstract

Purpose

The purpose of this study is to examine the influence of moral intensity on the ethical decision-making process of professional accountants based on a combined importance-performance map analysis (cIPMA).

Design/methodology/approach

Using partial least squares structural equation modeling (PLS-SEM) on data from 309 accountants, the study examined the relationships between four moral intensity dimensions: magnitude of consequences, social consensus, probability of effect and concentration of effect, and the ethical decision-making process. The study also methodologically complemented by a combined importance-performance map analysis and necessary condition analysis.

Findings

The findings reveal that moral recognition and moral judgment are necessary conditions for predicting accountants’ moral intent. However, in terms of importance and performance, moral recognition plays a less significant role compared to moral judgment. Furthermore, the influence of moral intensity dimensions is pronounced on moral recognition, while their influence on moral judgment and moral intent is more context dependent. This is also exhibited in the combined importance-performance map analysis results.

Research limitations/implications

The study highlights the importance of considering specific ethical dilemmas and the differential influence of moral intensity when developing strategies to strengthen ethical decision-making in the accounting profession. Future research is encouraged to explore how cultural backgrounds and diverse settings influence accountants’ ethical decision-making with tailored measurement tools for a more comprehensive understanding.

Originality/value

To the best of the authors’ knowledge, the study is among the first to complement the results of PLS-SEM with importance-performance map analysis and necessary condition analysis to examine the relationship between moral intensity and ethical decision-making of accountants.

Details

International Journal of Ethics and Systems, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2514-9369

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