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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.

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…

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…

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

Keywords

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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…

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

Keywords

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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…

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. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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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…

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

Keywords

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Article
Publication date: 8 November 2019

Mohammad Namazi and Hossein Rajabdorri

The purpose of this study is to propose a contemporary-specific model entitled “sustainable development model of accounting professional ethics (SDM-APE)” and empirically…

Abstract

Purpose

The purpose of this study is to propose a contemporary-specific model entitled “sustainable development model of accounting professional ethics (SDM-APE)” and empirically investigate and quantitatively prioritize its components.

Design/methodology/approach

The study adopts the mixed content analysis research method and integrates both qualitative and quantitative approaches. The necessary data for the initial model are extracted after examining 569 published articles related to professional ethics of accounting in Iran during 2005-2015. Then, the ethical codes are reviewed, summarized and extracted via “content analysis.” Based on the findings of this study, a sustainable accounting model is developed, which consists of four constructs, including personal, social, economic-organizational and environmental factors, with 69 components. Afterward, the model is tested through collecting questionnaires and simple random sampling by 217 academic and professional experts. Accordingly, the second-order confirmatory factor analysis in LISREL software is used.

Findings

The paper clearly demonstrates that ethics in the professional accounting are underpinned by four major constructs: personal, social, economic-organizational and environmental factors; all four mentioned constructs of the model are interconnected and affect professional ethics in accounting and maintain a proper goodness of fit. Meanwhile, social, personal, economic-organizational and environmental features reveal the greatest fit accordingly. The variable of “avoiding the misuse of organizational property and information” is the most important variable of the model. It is followed by deontology, responsibility and accountability for environment, preventing environment degradation and emission of environmental pollutants, promoting the culture of environmental conservation, standing in the second to fifth priority levels, respectively.

Originality/value

This paper has developed a contemporary practical model in professional accounting ethics, which is extensive and applicable to various organizations.

Details

Meditari Accountancy Research, vol. 28 no. 1
Type: Research Article
ISSN: 2049-372X

Keywords

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Article
Publication date: 2 March 2015

Anoma Ariyawardana, Ramu Govindasamy and Allan Lisle

Red lentils are one of the widely consumed food items in South Asia and this has created an enormous market opportunity for all players in the chain. Therefore, the…

Abstract

Purpose

Red lentils are one of the widely consumed food items in South Asia and this has created an enormous market opportunity for all players in the chain. Therefore, the purpose of this paper is to examine the most valued attributes of red lentils and to assess how consumer preferences vary across store type and by socio-demographic factors. Thereby, it was aimed to identify value chain interventions that are required to meet the consumer demand.

Design/methodology/approach

Sri Lanka was selected as the study location because of its significance as an importer. Through an intercept survey of 300 consumers in three store types, consumption pattern and preference for four attributes of red lentils, namely, size, colour, visual quality and price were collected. Data were also collected from retail and wholesale stores and from a processor. Conjoint analysis was used to analyse the consumer data.

Findings

A majority of the respondents consumed red lentils on a daily basis. Consumer preference rankings showed that consumers place a significantly greater level of importance on visual quality than other attributes. Trade-off patterns were different across store types and by socio-demographic factors. Grocery shoppers were willing to trade-off packaging to price while the reverse was true for supermarket shoppers. Retail and wholesale purchases were driven by quality.

Research limitations/implications

Findings highlight that chain effectiveness could be enhanced by offering bigger sized lentils while assuring quality.

Originality/value

This research uses a consumer driven assessment in identifying required value chain interventions.

Details

British Food Journal, vol. 117 no. 3
Type: Research Article
ISSN: 0007-070X

Keywords

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