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Effect of Nonlinear Non-homogeneity of Floating Granular Pile and Soil on Settlement

  • J. K. Sharma
  • Pooja GuptaEmail author
Original Contribution
  • 89 Downloads

Abstract

Ground improvement using granular piles (GPs) is a good alternative to a concrete pile because it increases the load carrying capacity and minimises the settlement of foundations. The present study incorporates the true field conditions with consideration of the nonlinear variation of deformation modulus for GP and soil both. An analytical methodology developed to incorporate nonlinear deformation modulus in pile and soil matrix. Thus, the response of non-homogeneous floating granular pile in non-homogeneous soil is evaluated with respect to settlement influence factor, normalised shear stresses, axial load distribution along granular pile–soil interface and percentage of load transferred to the base to study its true behaviour. An analytical approach based on the continuum is presented in terms of nonlinear variation of deformation modulus of the granular pile and surrounding soil. Formulations for pile elemental displacement equations incorporating linear to nonlinear non-homogeneity parameters, α and δ, for floating granular pile and β and ϒ for non-homogeneous soil are presented. With the increment in relative length of the pile (L/d), the reduction in the magnitude of settlement influence factor further increases. The increase in linear and nonlinear non-homogeneity parameters of soil, β and ϒ, reduces the shear stresses in the upper region of soft soil along with granular pile–soil interface and transfers them to the lower stiffer region of soil.

Keywords

Granular pile Non-homogeneity Deformation modulus Relative stiffness Shear stresses 

Abbreviation

GP

Granular pile

List of symbols

L

Length of granular pile (metre)

D

Diameter of GP = (2a) (metre)

S

Spacing of GPs (metre)

P

Load on GP (Kn)

Egp

Deformation modulus of granular pile material (Kn/m2)

Es

Deformation modulus of soil (Kn/m2)

νs

Poisson’s ratio of soil (dimensionless)

ESL

Deformation modulus of soil at base (Kn/m2)

Es0

Deformation modulus of soil at surface (Kn/m2)

Kb

Relative stiffness of granular pile at base = (Egp/EsL) (dimensionless)

Kgp0

Relative stiffness of granular pile = (Egp0/Es) (dimensionless)

τ

Shear stresses at GP–soil interface (Kn/m2)

Pb

Pile base load (Kn)

n

Total number of elements of GP (dimensionless)

Isp

Soil displacements influence factor (dimensionless)

Egp0

Stress-independent deformation modulus or deformation modulus at the top of granular pile (Kn/m2)

τ*

Normalised shear stresses of GP = (τ/(PdL)) (dimensionless)

z* (= z/L)

Normalised depth of GP (dimensionless)

α

Linear non-homogeneity parameter of granular pile (dimensionless)

δ

Nonlinear non-homogeneity parameter of granular pile (dimensionless)

β

Linear non-homogeneity parameter of soil (dimensionless)

ϒ

Nonlinear non-homogeneity parameter of soil (dimensionless)

Notes

Acknowledgements

I am highly indebted and grateful to Professor M.R. Madhav, J.N.T.U. Hyderabad, for his valuable suggestions, His high appreciation and positive attitude about the author’s research ability have played an important role.

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Copyright information

© The Institution of Engineers (India) 2018

Authors and Affiliations

  1. 1.Civil Engineering DepartmentRajasthan Technical UniversityKotaIndia
  2. 2.KotaIndia

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