7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

1/19

Ground Improvement by

Vibro Stone Column

Desh Raj Sonyok

Saheem Ahmed

CE 596 Soil Improvement

Term paper Fall 2006

Civil Engineering Department

New Mexico State University

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

2/19

Importance o Vibro !eplacement

Reduce settlement of soil

Improve bearing capacity

Improve shear strength of soil

Liquefaction mitigation

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

3/19

Soil" Suitable or t#e Vibro

!eplacement

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

4/19

Con"truction $rocedure" o t#e

Vibro !eplacement %et#od

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

5/19

&naly"i" on Vibro !eplacement

Stone Column

e! mathematical analysis available for

the vibro replacement stone column

"riebe #$%%&' proposed an equation forthe improvement factor as a function of

area replacement ratio( )e further

proposed a design chart for the

improvement factor !hich is much morecommon in practice(

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

6/19

$reibe'" ()995* E+uation

Improvement factor

equation #"reibe*

+$%%&'

Settlement after the

improvement

( )

+= 11..4

5.1

0

AAK

AA

A

An

cac

cc

( )

+

=

$$,

&$

AA.K.

AA

A

A

D

dpS

cac

cc

s

( )-,&-cac

tanK =

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

7/19

$riebe ()995* ,e"i-n C#art

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

8/19

&naly"i" and Compari"on

Stone Column to Prevent Settlement in

Ireland

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

9/19

Measured Settlements

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

10/19

Soil Parameters and Settlement

Before After Before

After

Depth (m) Soil type Nval

ue

E(MPa

)

Nval

u

e

E(MPa

)

s (mm) s(m

m

)

Recorded s(mm)

Estimated s(mm) *

00!"# SP $0 $0 $% $% "$ $% &0 ! '0 $'

"#!0 SP 0 0 $0 $

0!'0 M+,

& & $' $$

'0!%# -. $ $0 0 $ '

%#!$$0 -. "0 0 "0 0 # #

$$0!$&0 ,/ ' "% ' "%

$&0!$0 -. "# '0 "# '0 " "

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

11/19

Stone Column to Prevent

Settlement in South Arica

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

12/19

Settlement Measurements

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

13/19

Calculate Settlement

Structural load #00 1Pa 2 '00 1Pa-rid type tria34ular

Avera4e le34th % m 2$& mDiameter '&0 mm

5o3e Spaci34 (m) A (m) A+A,

Settleme3t (mm)

$ $# $6& # 60

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

14/19

Settlement or t#e Vibro Stone

Column E+uation $ropo"ed %et#od

cs

s

s

AA

Aa

+=

.

se$

ea

+

=

c

sn

=

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

15/19

( )scss

a.a. += $

( ) =

+= (

a$n$

$c

s

c

( ) ( )[ ]

+

+= .c.

.ss

c"

("logea$a$

)/S

=

=

=

..H.bH

..V.bV

..bd

ss

ss

ssv

Average stress over the

unit cell

Stress concentration on the

surrounding soil

Settlement equation ofthe surrounding soil

If compressibility of the stone

column is bs*

Settlement of the stone

column

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

16/19

0he proposed equation gives an estimation of

the settlement of the surrounding soil and thecolumn alone( 0he final settlement of the site !ill

be definitely !ith in the limit proposed above(

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

17/19

Limitation of the equation

0he proposed equation is applicable to the

homogeneous soil !ith clay to be improved( 0he

equation to be modified for the layered soils

0his method assumes constant compressibilityinde1 before and after treatment

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

18/19

Conclu"ion"

0he primary purpose of this method is to improve the

settlement characteristics of the soft soil* increase load

bearing capacity* and shear strength

2stimation of settlement for the design of vibro stone

column proposed by "riebe is found to be more

conservative

A rational method of estimating settlement in a

homogenous soil is proposed based on the basic concept

of composite material and soil mechanics(

Result of this preliminary !ork is yet to validate

numerically and in the field(

Detailed research in future is necessary to check its

validity and applicability(

7/24/2019 Vibrostonecolumnpresentationfinal 141119184232 Conversion Gate01

19/19

0hank 3ou