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Study of Effect of Stiffening and Rigidity of Bearing Stratum-On Tip Load for Single and Group of Granular Piles

  • Vaibhaw GargEmail author
  • Jitendra Kumar Sharma
Conference paper
Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 55)

Abstract

In the modern time due to population explosion and growing demands with constrains of limited land resources, engineers are forced to use those areas for construction, which have soft soils or even other worst soil conditions. Application of granular piles is one among the various existing solution to the problem. The present paper investigates the comparison of variation in the percentage tip load of the partially stiffened granular pile. The granular pile is partially stiffened means some portion of granular pile at the top is replaced by a better engineering material. The effect of stiffening is studied in two forms namely relative length of stiffening, i.e., the percentage length of stiffening considered from top of the granular pile and the relative stiffness of the material of top portion of granular pile. The analysis is carried out for both categories of granular piles viz. floating and end-bearing. This paper reveals the study of variation in percentage base load, showing the effect of relative length, normalized spacing between the partially stiffened granular piles, stiffening parameters, rigidity of bearing stratum, etc., on a single and group of two, three and four axially loaded, symmetrically placed, partially stiffened granular piles each loaded with equal load is studied. It was found that the pile percentage tip load increases with the increase in stiffening parameters as well as with the rigidity of the bearing stratum in all cases. The stiffening effect incorporated at the top of the granular piles is more effective in transferring the loads, in case of relative stiffening range of granular pile. It also acts as an effective remedial measure for the problem of bulging of the granular piles.

Keywords

Ground improvement Granular pile Relative length of stiffening Relative stiffness Bearing stratum 

Abbreviations

GP

Granular pile

L

Length of granular pile

n

Total number of elements of GP

d = (2a)

Diameter of granular pile

P

Axial load on each granular pile of granular pile group

Pb

Load on the base of the GP

L/d

Relative length of granular pile

Egp

Deformation modulus of un-stiffened portion of granular pile

Eb

Deformation modulus of bearing stratum

Eb/Es

Relative stiffness of bearing stratum on which the piles are resting

Egpst

Deformation modulus of stiffened portion of granular pile

Es

Deformation modulus of soil

νs

Poisson’s ratio of soil

Kgp

Relative stiffness of granular pile = (Egp/Es)

pb

Granular pile base pressure

s

Spacing between center to center of the granular piles

s/d

Normalized spacing, between granular piles

ρ

Normalized displacement of GP along its length

Ls

Length of the pile stiffened from the top of the pile

η = Ls/L

Relative length of stiffening from top of GP

χ

Relative stiffness factor (ratio of Kgp of stiffened top portion of GP to Kgp of the un-stiffened portion of GP) (χ > 1, for stiffening)

(Pb/P) × 100

Percentage load transferred to the base of a GP in a group of GPs

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Copyright information

© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  1. 1.Civil Engineering Department, University DepartmentRajasthan Technical UniversityKotaIndia

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