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Full-Text Articles in Engineering
Radial Consolidation Of Clay Using Compressibility Indices And Varying Horizontal Permeability, B. Indraratna, C. Rujikiatkamjorn, I. Sathananthan
Radial Consolidation Of Clay Using Compressibility Indices And Varying Horizontal Permeability, B. Indraratna, C. Rujikiatkamjorn, I. Sathananthan
Cholachat Rujikiatkamjorn
A system of vertical drains with surcharge load to accelerate consolidation by shortening the drainage path is one of the most popular methods of soft ground improvement. The conventional radial consolidation theory (including smear and well resistance) have been commonly employed to predict the behaviour of vertical drains in soft clay. Its mathematical formulation is based on the small strain theory, and for a given stress range, a constant volume compressibility (mv) and a constant coefficient of lateral permeability (kh) are assumed. However, the value of mv varies along the consolidation curve over a wide range of applied pressure (Dp). …
Radial Consolidation Theories And Numerical Analysis Of Soft Soil Stabilisation Via Prefabricated Vertical Drains, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Rohan T. Walker
Radial Consolidation Theories And Numerical Analysis Of Soft Soil Stabilisation Via Prefabricated Vertical Drains, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Rohan T. Walker
Cholachat Rujikiatkamjorn
In this paper, an analytical solution based on actual radial soil permeability and compressibility is proposed considering the impact of parabolic variation of permeability in smear zone. The use of the spectral method for multilayered soil consolidation is introduced and verified. The Cavity Expansion Theory is employed to predict the extent of soil disturbance (smear zone) caused by the installation of mandrel driven vertical drains. The smear zone prediction is then compared to the data obtained from large-scale radial consolidation tests. Furthermore, the advantages and limitations of vacuum application through vertical drains are discussed using the proposed solutions. The applied …
Analytical Solutions And Design Curves For Vacuum-Assisted Consolidation With Both Vertical And Horizontal Drainage, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Analytical Solutions And Design Curves For Vacuum-Assisted Consolidation With Both Vertical And Horizontal Drainage, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
A system of vertical drains combined with vacuum preloading is an effective method for promoting radial flow to accelerate soil consolidation. This study presents the analytical modeling of a consolidation of vertical drains incorporating vacuum preloading considering both vertical and horizontal drainage. The effects of a number of dimensionless parameters involving the drain length, soil permeability and vacuum pressure are examined through average excess pore pressure, degree of consolidation, associated settlement and time factor analyses. An analysis of selected case histories compliments the use of the proposed solutions. Design charts are also presented for practical use.
Three-Dimensional Analysis Of Soft Soil Consolidation Improved By Prefabricated Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Three-Dimensional Analysis Of Soft Soil Consolidation Improved By Prefabricated Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
A system of prefabricated vertical drains (PVDs) with a surcharge load is an effective method for accelerating soil consolidation by promoting radial flow. This study presents a three-dimensional (3D) finite element model for soft soil improved by a single drain. In the finite element analysis, the actual rectangular PVD cross-section is considered, and the equivalent drain diameter is then back calculated based on the consolidation curves. The numerical predictions are then compared to previous studies. The settlements observed in the laboratory are subsequently compared with the three-dimensional finite element analysis incorporating the modified Cam-Clay model and Hansbo’s theory.
Elastic Visco-Plastic Consolidation Modelling Of Soft Clays Improved By Geosynthetic Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Elastic Visco-Plastic Consolidation Modelling Of Soft Clays Improved By Geosynthetic Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
In this paper, an elastic viscoplastic (creep) model is incorporated into the consolidation equation to calculate settlements and excess pore pressures. A finite difference formulation for fully coupled axisymmetric consolidation is adopted to model both vertical and radial consolidation of a multi-layered soil. The effect of smear, non-linear stiffness and varying soil permeability with void ratio can be included in the analysis. The formulation is easily executed in an electronic spreadsheet such as Excel, and it is then validated by existing solutions. Finally, the analysis of a selected case history employing the writers’ formulation is employed to analyse an embankment …
Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn
Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn
Cholachat Rujikiatkamjorn
Construction of rail tracks requires appropriate improvement techniques for ballast and underlying soft formation soil, both of which deform and degrade progressively under heavy train loads. This paper aims to demonstrate and discuss some major aspects in relation to stabilisation of ballasted rail tracks overlaying soft formation soils. The use of geocomposites (i.e. bonded geogrid-geotextile layers) for enhancing the performance of rail tracks is described, with the aim of achieving reduced track settlement, increased resilient modulus and decreased ballast degradation. The effects of increasing the confining pressure on rail tracks in regard to particle breakage are studied using laboratory tests. …
Soft Ground Improvement By Vacuum-Assisted Preloading, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Soft Ground Improvement By Vacuum-Assisted Preloading, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
This paper describes the behaviour of soft soil foundation stabilized with vacuum-assisted preloading at the New Bangkok International Airport, Thailand. An analytical solution considering the variation of soil permeability and compressibility and a finite element analysis based on an equivalent plane strain model developed by the authors are employed to investigate the performance of the test embankment. The converted equivalent plane strain parameters are incorporated in the finite element code ABAQUS. The associated settlement, excess pore pressure and lateral movement are predicted and compared with the available field measurement. The data indicate that the efficiency of the prefabricated vertical drains …
Soft Clay Stabilization With Geosynthetic Vertical Drains Beneath Road And Railway Embankments: A Critical Review Of Analytical Solutions And Numerical Analysis, Buddhima Indraratna, Cholachat Rujikiatkamjorn, J. Chu
Soft Clay Stabilization With Geosynthetic Vertical Drains Beneath Road And Railway Embankments: A Critical Review Of Analytical Solutions And Numerical Analysis, Buddhima Indraratna, Cholachat Rujikiatkamjorn, J. Chu
Cholachat Rujikiatkamjorn
In the wide array of existing ground improvement schemes, the use of vertical drains with vacuum preloading is considered as the most effective and economical method for improving soft clays (normally consolidated to lightly over-consolidated) prior to construction of infrastructure. Vertical drains installed to significant depths promote radial flow inducing consolidation rapidly enhancing the shear strength of the compressed ground. In this paper, the analytical solutions based on lateral soil permeability (parabolic variation) are discussed considering the variation of vacuum pressure with depth along the prefabricated vertical drains (PVD). Using the Cavity Expansion Theory (CET), the smear zone caused by …
Predictions And Observations Of Soft Clay Foundations Stabilized With Geosynthetic Drains And Vacuum Surcharge, Buddhima Indraratna, Cholachat Rujikiatkamjorn, A. S. Balasubramaniam, V. Wijeyakulasuriya
Predictions And Observations Of Soft Clay Foundations Stabilized With Geosynthetic Drains And Vacuum Surcharge, Buddhima Indraratna, Cholachat Rujikiatkamjorn, A. S. Balasubramaniam, V. Wijeyakulasuriya
Cholachat Rujikiatkamjorn
This chapter starts with an introduction of a revised analytical model of radial drainage with vacuum preloading in both axisymmetric and plane strain conditions. Observed from large-scale radial drainage consolidation tests, the influence of vacuum pressure distribution along the drain length is examined through the dissipation of average excess pore pressure and associated settlement. The details of an appropriate conversion procedure by transforming permeability and vacuum pressure between axisymmetric and equivalent plane strain conditions are described through analytical and numerical schemes. The effects of the magnitude and distribution of vacuum pressure on soft clay consolidation are investigated on the basis …
Improvement Of Soft Clays Using Vacuum-Assisted Consolidation Method, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Improvement Of Soft Clays Using Vacuum-Assisted Consolidation Method, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
In this study, the analytical modeling of one-dimensional consolidation by vertical drains with vacuum preloading considering both vertical and horizontal drainage is presented. In this method, the total degree of consolidation based on excess pore water pressure dissipation is related to the time factor (Th), drain configuration and anisotropic soil permeability. The analytical predictions are compared with the observed data from consolidation testing. Three different test series were conducted in a large-scale consolidation apparatus designed and installed at the University of Wollongong. It is shown that the authors’ analytical model can accurately predict the laboratory behavior. Finally, the analysis of …
Analytical Modeling And Field Assessment Of Embankment Stabilized With Vertical Drains And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Analytical Modeling And Field Assessment Of Embankment Stabilized With Vertical Drains And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Cholachat Rujikiatkamjorn
This study presents an analytical model of radial drainage with vacuum preloading using compressibility indices and varying horizontal permeability and considers the influence of linearly distributed vacuum pressure along the drain. An analytical solution based on the Cylindrical Cavity Expansion theory is used to evaluate the extent of the smear zone along the drain length and predict the performance of an embankment stabilized with vacuum-assisted prefabricated vertical drains at the New Bangkok International Airport (NBIA). Here, a significantly reduced height of sand surcharge could be applied because excess pore pressure was reduced by vacuum preloading. The performance of the embankment …
Soft Soil Stabilisation With Special Reference To Road And Railway Embankments, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V. Wijeyakulasuriya, Mohamed A. Shahin, D. Christie
Soft Soil Stabilisation With Special Reference To Road And Railway Embankments, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V. Wijeyakulasuriya, Mohamed A. Shahin, D. Christie
Cholachat Rujikiatkamjorn
Much of Australian railway tracks traverse coastal areas containing soft soils and marine deposits. Pre-construction stabilization of soft formation soils by applying a surcharge load alone often takes too long. The installation of prefabricated vertical drains (PVDs) can reduce the preloading period significantly by decreasing the drainage path length, sometimes by a factor of 10 or more. The analytical solution based on actual radial soil permeability is proposed considering the variation of vacuum pressure, and the Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains. The predicted smear zone and …
Performance And Prediction Of Soft Clay Behavior Under Vacuum Conditions, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Performance And Prediction Of Soft Clay Behavior Under Vacuum Conditions, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Cholachat Rujikiatkamjorn
This paper describes the behavior of soft soil foundation under vacuum-assisted preloading at the Second Bangkok International Airport, Thailand. An analytical solution considering the variation of soil permeability and compressibility is proposed. The associated settlement and excess pore pressure at the embankment centerline are predicted and compared with the available field measurement. The field data show that the efficiency of this improvement technique depends on the magnitude and distribution of vacuum pressure as well as on the extent of air leak protection. The height of sand surcharge and consolidation time can be significantly reduced in comparison with the conventional method …
Laboratory Modeling Of Consolidation Behavior Of Soft Clays Using Vacuum-Surcharge Consolidation Method, Cholachat Rujikiatkamjorn, Buddhima Indraratna, M. Sakr
Laboratory Modeling Of Consolidation Behavior Of Soft Clays Using Vacuum-Surcharge Consolidation Method, Cholachat Rujikiatkamjorn, Buddhima Indraratna, M. Sakr
Cholachat Rujikiatkamjorn
In this study, the large-scale apparatus used to examine vacuum preloading in conjunction with conventional surcharge loading. Several tests were performed to examine the effect of a vacuum and determine parameters such as the extent of smear zone and the soil permeability characteristics. The settlement and excess pore pressure associated with a combined vacuum and surcharge load indicates that applying a vacuum has specific benefits. The analytical modeling of one-dimensional consolidation by vertical drains with vacuum preloading considering both variation of soil compressibility and permeability is used to predict the soil consolidation behavior. It is shown that the analytical model …
Laboratory Determination Of Efficiency Of Prefabricated Vertical Drains Incorporating Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Laboratory Determination Of Efficiency Of Prefabricated Vertical Drains Incorporating Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Cholachat Rujikiatkamjorn
This paper is mainly concerned with a laboratory study to investigate the effect of vacuum preloading. Two separate series of tests were conducted in a large-scale consolidation apparatus designed and installed at the University of Wollongong, with axial load increments of 30 and 50 kPa. The first series of tests were performed based on the conventional method (i.e. without vacuum preloading). For the second series, a vacuum pressure of 100 kPa was applied during the process of consolidation. The corresponding settlement behaviour was recorded and plotted. The extent of smear zone was examined by the variation of permeability of small …