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Load and Deformation Mechanisms in Geosynthetic-Reinforced Piled Embankments

  • Ewerton C. A. Fonseca
  • Ennio M. Palmeira
  • Michael V. Barrantes
Original Paper
  • 26 Downloads

Abstract

Geosynthetic-reinforced piled embankments have been increasingly used to stabilise embankments over soft soils. The presence of the reinforcement reduces the stresses transferred to the soft foundation and improves the efficiency of the transference of loads to the piles. Therefore, significant reductions in fill settlements and in lateral displacements of the soft soil can be obtained. However, the design of this type of work is still complex and simple theoretical approaches are commonly employed in practice. This paper investigates the load transference and deformation mechanisms in reinforced piled embankments by means of large-scale laboratory tests. Four types of geosynthetics, including a geogrid and three geotextiles, were tested with varying values of tensile stiffness. Surcharges on the fill surface of up to 40 kPa (200 kPa under prototype conditions) were applied. Test measurements were compared with predictions from some currently employed analytical methods. The results obtained showed the benefits of using geosynthetic reinforcement in this type of work and that significant variations among predictions by analytical methods and measurements may occur. It is recommended that sound engineering judgement be exercised when using analytical solutions in the design of geosynthetic-reinforced piled embankments on soft subgrades.

Keywords

Geosynthetics Piled embankments Reinforcement Design methods 

Abbreviations

BS

British standard, BS 8006—British method

BS-H&R

BS method with Hewlett and Randolph (1988) arching theory

BSmod

Modified BS method

CA

Concentric arches

EBGEO

Empfehlungen für Bewehrungen aus Geokunststoffen—German method

FEM

Finite element method

PET

Polyester

PP

Polypropylene

SM

Simplified method

TSC

Total stress cell

TZG

Terzaghi’s method

List of Symbols

a

Cap width (m)

CU

Soil coefficient of uniformity (dimensionless)

d

Distance between caps (= s − a) (m)

Dn

Soil particle diameter for which n% of the remaining particles have smaller diameters (mm)

Ep

Pile efficacy (dimensionless)

h

Embankment height (m)

H

Equivalent embankment height (= h + q/γ) (m)

J5%

Geosynthetic secant tensile stiffness at 5% strain (kN/m)

MA

Geotextile mass per unit area (g/m2)

Pp

Load on the pile (kN)

q

Surcharge at the embankment surface (kPa)

R2

Coefficient of determination of the least square regression line (dimensionless)

s

Pile spacing (m)

SRR

Stress reduction ratio (dimensionless)

Tmax

Geosynthetic tensile strength (kN/m)

α

Slope of least square regression line

γ

Soil unit weight (kN/m3)

δ

Maximum fill settlement between caps (mm)

ε

Reinforcement tensile strain (dimensionless)

εmax

Maximum tensile strain (%)

σvr

Vertical stress on the reinforcement layer (kPa)

Notes

Acknowledgements

The authors would like to thank the following institutions for their help in the research activities described in this paper: The University of Brasília, CNPq-National Council for Scientific and Technological Development, Capes-Brazilian Ministry Education and geosynthetic manufacturers.

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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Ewerton C. A. Fonseca
    • 1
  • Ennio M. Palmeira
    • 2
  • Michael V. Barrantes
    • 2
  1. 1.Civil Construction DepartmentFederal Technological University of ParanáCampo MourãoBrazil
  2. 2.Department of Civil and Environmental EngineeringUniversity of BrasíliaBrasíliaBrazil

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