DEFORMATION ANALYSIS OF EMBANKMENTS (original) (raw)
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In 1986, the Malaysian Highway Authority constructed a series of trial embankments on the Muar Plain (soft marine clay) with the aim of evaluating the effectiveness of various ground improvement techniques. This study investigates the effect of two such ground improvement schemes: (a) preloading of foundation with surface geogrids and synthetic vertical drains and (b) sand compaction piles. The paper is focused on the finite element analysis of settlements and lateral displacements of the soft foundation. In scheme (a), the numerical predictions are compared with the field measurements. In scheme (b), only the numerical analysis is presented and discussed in the absence of reliable measurements due to the malfunctioning of the electronic extensometer and inclinometer system during embankment construction. The current analysis employs critical state soil mechanics, and the deformations are predicted on the basis of the fully coupled (Biot) consolidation model. The vertical drain pattern is converted to equivalent drain walls to enable plane strain modelling, and the geogrids are simulated by linear interface slip elements. The effect of sand compaction piles is investigated considering both ideal drains and non-ideal drains, as well as varying the pile stiffness. @ 1997 by John Wiley & Sons, Ltd.
FINITE ELEMENT ANALYSIS OF EMBANKMENTS ON SOFT CLAY
Soft clay soil is characterized by high compressibility and low shear strength, so the settlement is the major problem facing the embankment constructed on soft clay soils and causes an increase in the cost of maintenance. Numerical analysis has been carried out to study some parameters affect the settlement of embankment founded on soft clay such as, the clay thickness (h c) and the width of the embankment base (B), and the stiffness of clay layer. The lateral extrusion due to the settlement of the embankment was also included. The results of the finite element analysis were verified using field and the traditional method results. Numerical analysis was performed using the GEO5 finite element program. Finally, the results of the finite element analysis were discussed in detail.
In this lecture the interpretations of fully instrumented tests embankments and their role in the development of appropriate ground improvement techniques for highways, motorways and airfields on soft clay deposits is illustrated through well documented case studies in Bangkok, Thailand; Muar Flat Site in Kuala Lumpur and in Southeast Queensland. For the Bangkok Plain and with sand backfills the performance of embankments with different schemes of vertical drains was evaluated over a period of 25 years. Aspects such as recharging effects due to the drains, inadequate measures in maintaining vacuum during vacuum applications and possible hydraulic connections with large diameter drains are discussed. For the Muar test embankments, the role of fill strength in residual soil embankment and the field deformation analysis in separating consolidation settlement from immediate settlement and creep settlements is presented. Novel interpretations of settlement from pore pressure dissipations, secondary settlement from field measurements and decay of lateral deformation rate with time were also made.
Interpretation and Analysis of Test Embankments in Soft Clays with and without Ground Improvement
Proceedings of the …, 2007
In this lecture the interpretations of fully instrumented tests embankments and their role in the development of appropriate ground improvement techniques for highways, motorways and airfields on soft clay deposits is illustrated through well documented case studies in Bangkok, Thailand; Muar Flat Site in Kuala Lumpur and in Southeast Queensland. For the Bangkok Plain and with sand backfills the performance of embankments with different schemes of vertical drains was evaluated over a period of 25 years. Aspects such as recharging effects due to the drains, inadequate measures in maintaining vacuum during vacuum applications and possible hydraulic connections with large diameter drains are discussed. For the Muar test embankments, the role of fill strength in residual soil embankment and the field deformation analysis in separating consolidation settlement from immediate settlement and creep settlements is presented. Novel interpretations of settlement from pore pressure dissipations, secondary settlement from field measurements and decay of lateral deformation rate with time were also made.
1 Interpretation and Analysis of Test Embankments in Soft Clays with and without Ground Improvement
2014
Abstract: In this lecture the interpretations of fully instrumented tests embankments and their role in the development of appropriate ground improvement techniques for highways, motorways and airfields on soft clay deposits is illustrated through well documented case studies in Bangkok, Thailand; Muar Flat Site in Kuala Lumpur and in Southeast Queensland. For the Bangkok Plain and with sand backfills the performance of embankments with different schemes of vertical drains was evaluated over a period of 25 years. As-pects such as recharging effects due to the drains, inadequate measures in maintaining vacuum during vacuum applications and possi-ble hydraulic connections with large diameter drains are discussed. For the Muar test embankments, the role of fill strength in residual soil embankment and the field deformation analysis in separating consolidation settlement from immediate settlement and creep set-tlements is presented. Novel interpretations of settlement from pore pressure...
Stress and Deformation due to Embankment Widening with Different Treatment Techniques
A two-dimensional (2-D) finite element (FE) model was developed to analyze the deformation and stress of embankment on soft ground due to widening with different treatment techniques. It is found that the embankment widening induces transverse gradient change due to differential settlements and horizontal outward movements at the shoulder of the existing embankment. Embankment widening also increases the shear stress along the slope of the existing embankment, especially at the foot of slope. The failure potential due to embankment widening may increase with the increase of widening width when the widening width is smaller than 8.5 m, but may decrease with the increase of widening width as the widening width is greater than 8.5 m. The effectiveness of four ground and embankment treatment techniques, including geosynthetic reinforcement, light-weight embankment, deep mixed columns, and separating wall were compared. The results indicate that these treatments reduce the differential settlements and improve the stability. The light-weight embankment has the most effectiveness among four treatments. By using the fly-ash backfill material in widening, the transverse gradient change decreases from 0.5%−1.3% to 0.26%−0.8% and the maximum horizontal displacement decreases from 2.76 cm to 1.44 cm.
Structural behaviour and parametric study of reinforced embankments on soft clays
Computers and Geotechnics, 2001
Geotechnical behaviour of a reinforced embankment on soft ground is studied by a numerical model based on the ®nite element method. Special emphasis is given to the stress states (stress levels and pore pressures), displacements, tensile forces in the geosynthetic and overall stability, during and after construction. The in¯uence of some parameters, namely geosynthetic stiness and viscosity, embankment width and construction sequence, is also analysed. Several conclusions are obtained. #
Results from a geotechnical benchmark exercise of an embankment on soft clay
2003
The results of a simple geotechnical benchmark problem, an embankment on soft clay, are presented and discussed. The problem has been simulated with several constitutive models: models that are commonly used for practical geotechnical engineering problems, as well as advanced models developed by SCMEP Network partners. These advanced constitutive models account for initial and induced anisotropy, destructuration and creep or combinations of these features. The comparisons highlight the effects of these features on soft clay response and demonstrate the differences between alternative constitutive modelling approaches.
Influence of features of natural soft clay on behaviour of embankment
Journal of Central South University, 2011
The influence of different features of natural soft clays, namely anisotropy, destructuration and viscosity, on modelling the time-dependent behaviour of Murro embankment was investigated. The newly developed elasto-viscoplastic models were enhanced for determining viscosity parameters in a straightforward way and adopted for the finite element analysis. The same set of common parameters determined from conventional triaxial and oedometer tests was employed for all models, with additional parameters required for representing different soil features. The finite element predictions by using models coupled with BIOT's consolidation theory were compared with each other and with field data for settlement, horizontal displacement and excess pore pressures. In addition, the stress paths under the embankment loading were also compared with each other to improve the understanding of the effect of different soil features. All simulations demonstrate that all three features significantly influence the predictions. As a consequence, accounting for soil features needs to be carefully considered when they are applied to a construction site.
Prediction of embankment performance using numerical analyses – Practitioner’s approach
Computers and Geotechnics, 2018
A 3 m high embankment with prefabricated vertical drains was constructed over Ballina clay. It has been thoroughly instrumented for monitoring over three years after construction. Based on the data available at the site, the authors undertook Class A predictions of embankment performance using two approaches: a simple 1D consolidation analysis and a sophisticated large strain finite element analysis (FEA) using Soft Soil Creep (SSC) model. Class C predictions were then conducted using the SSC model in FEA, with and without large strain. It is demonstrated that the SSC model can give satisfactory results when large strain FEA was used.