Design of Stone Columns Hooghly

1.0 1.0

Capa Capaci city ty of Ston Stone e colu column mn of 600 600 dia dia.. 15m 15m leng length th & 1.5m 1.5m tra train ingu gula larr spac spacin ing g

1.1

Column Dimensions :

1.2

Diameter of Stone Columns

=

0.6 m

Initial Spacing of Column Pattern of Grid

= =

1.5 m c/c Triangular 

Coesion of Soil "ul# densit$ of soil %a&o'e ( T)

= =

"ul# densit$ of soil %&elo* ( T) Dec# le'el Design (ater le'el eigt of soil a&o'e *ater le'el  ngle of internal internal friction of fill %Stone material)

= = = = =

!5 #3/m 16 #3/m! 6 #3/m!

Soil Details :

,oading intensit$ o'er te column

=

2.0

Calculation

2.1

Bear Bearin ing g Sup Supp port ro! ro!id ide ed "y "y Su Surro rround unding ing Soi Soill :ltimate "earing capacit$ ; ult

0 -  5

m a&o'e +S, m a&o'e +S, m deg.

10 #3/m

( ere4 c = Coesion of surrounding soil 3c = "earing capacit$ factor

 = = =

c 2 3c !5 #3/m 5.1

ence4 :ltimate "earing capacit$ ; ult

 =

1. #3/m

Safe "earing capacit$4 ; safe ( ere4 7oS = 7actor of Safet$

 = =

ence4 Safe "earing capacit$4 ; safe

 =

 rea co'ered co'ered &$ eac stone column column ( ere4 S = Spacing of Stone columns

= =

 rea co'ered co'ered &$ eac stone column4 column4 s  rea of eac stone column column 4 c

= =

1.5 m 0.8 m

 rea of surrounding surrounding soil for eac eac column   = s - c

= =

s - c 1.6 m   2 ; safe

Safe load ta#en &$ surrounding soil

= =

;ult / 7oS ! 5. #3/m 0.866 2 S  1.50 m c/c

.0 #3 99%1 )

1

2.2

#ield load of Stone Column σ'o

2.$

 =

!. #3/m

%ta#en at a dept of  times dia.of column) c = Coesion of surrounding soil

=

!5 #3/m


=

 3φ > %σro @ c)

 =

!!.1508 #3/m

=

rea of Column

 =

6!.000 #3

Safe load on stone column (ere4 7oS = 7actor of Safet$

= =


ence4 Safe load on stone column

=

0.6

15.8 #3 99%)

Surcharge %ffect Increase in radial Stress δ σr  ;safe

 =

;safe / ! 2 %1 @  o)

= =

5. #3/m 0.6

ence4 Increase in radial Stress δ σr 

 =

!.8 #3/m

Increase in $ield Stress 7;A 7or φ = 04

=

 3φ 2 δ σr 2 7;A

 =

1

=

55. #3/m

(ere4

#o

ence4 Increase in $ield Stress Increase in $ield load

2.

5.80

o = Coefficient of lateral eart pressure σ'o = ?ffecti'e 'ertical stress


=

 3φ > %σro @ c)

Safe Increase in $ield ,oad

=  = =

(ere4 7oS = 7actor of Safet$ ence4 Safe Increase in $ield ,oad

= =

Increase in Stress > rea of col. .1 #3 Increase in
'otal Safe (oad Total safe load of eac column

=  =

?;uations %1) @ %) @ %!) !!.8 #3



2.5

$.0

(oading on Column ,oading o'er te surface4 ;

=

 rea co'ered &$ eac column4 s ,oad on eac column

= =

10 #3/m 1.5 m ; 2 s

 = B

. #3 Safe ,oad on eac column )ence *.+.

Diameter of Stone Columns

=

0.6 m

Initial Spacing of Column Pattern of Grid

= =

Summary

1.5 m c/c Triangular 

!

1.0

Settlement of Stone Column treated ground

1.1

Column Dimensions : Diameter of Stone Columns Initial Spacing of Column Pattern of Grid

= = =

0.6 m 1.5 m c/c Triangular 

Stone Column Capacity : ,oad carried &$ surrounding soil ,oad carried &$ stone column Increase in $ield ,oad for surcarge effect

= = =

.0 #3 15.80 #3 8.1! #3

Total ,oad carried &$ stone column

=

!!.8 #3

Cross Section Details :  rea co'ered &$ eac stone column4   rea of eac stone column 4 s

= =

1.5 m 0.8 m

 rea of surrounding soil for eac column  g =  - s

= =

 - s 1.6 m

1.2

1.$

eplacement ratio4 a s = s / %s @ g) = s /  = 1.

,ertical Stresses : ertical stress in column4 σs ertical stress in soil4 σg Stress concentration ratio4 n =

1.5

 =  =

σs / σg

Settlement : +odulus of 'olume cange4 m' ,a$er tic#ness Settlement of treated ground = %m' 2 σg 2 )

" 1  !  5

Dept !.5 .5  !.5 .5

' %cm/#g) 0.00! 0.0065 0.005 0.006 0.018

0.151

=

= =  =  =

1.8 #3/m 5. #3/m 1!.058

0.0055 cm/#g 0.000055 m/#3 15 m 0.0 m .66 mm