Geotechnical Engineering-I [Lec #20: Consolidation Settlement Computation]

1
Geotechnical Engineering–I [CE-221]
BSc Civil Engineering – 4th Semester
by
Dr. Muhammad Irfan
Assistant Professor
Civil Engg. Dept. – UET Lahore
Email: mirfan1@msn.com
Lecture Handouts: https://groups.google.com/d/forum/2016session-geotech-i
Lecture # 20
6-Apr-2018

2
SETTLEMENT COMPUTATIONS
For an undisturbed soil specimen.
oo e
e
H
H




1
εf = εL
Field Laboratory
o
oC
e
e
HHS



1
where,
SC = Consolidation settlement in the field

3


H
Ways to estimate consolidation settlement:
(b) Using mv
(a) Using e-log v’ plot
Consolidation settlement, Sc = mv .  . H
H
e
e
Ssettlement
o
c



1
eo, vo’, Cc, Cr, p’, mv
Oedometer test
next slide
e
a
m V
V


1

4
'
''
log
vo
vo
cCe

 

If the clay is normally consolidated, the entire loading path is along the VCL.
initial
vo’
eo
vf’= vo’+ ’
e
final
1
Cc
H
e
e
S
o
c



1
VCL





 








'
''
log
1 vo
vo
o
c
c
e
C
HS


’vf
'
)'(
log
vo
vo
C
e
C

 


CASE I: ’p ≈ ’vo < ’vf
p’

5
If the clay is over-consolidated, and remained so by the end of consolidation.
CASE II: ’vo < ’vf < ’p
initial
vo’
eo
vf’= vo’+ 
e final
1
Cc
VCL
1
Cr
p’
'
''
log
vo
vo
rCe

 

H
e
e
S
o
c



1





 








'
''
log
1 vo
vo
o
r
c
e
C
HS


’vf
'
)'(
log
vo
vo
e
Cr

 



6
If the over-consolidated, soil becomes normally consolidated by the end of
consolidation.
CASE III: ’vo < ’p < ’vf
initial
vo’
eo
vf’= vo’+ 
e
final
1
Cc
VCL
1
Cr
p’
'
''
log
'
'
log
p
vo
c
vo
p
r CCe



 

H
e
e
S
o
c



1







 






















'
''
log
1
'
'
log
1
p
vo
o
c
vo
p
o
r
c
e
C
H
e
C
HS




’vf

7
CONSOLIDATION – SUMMARY
H
e
e
Ssettlement
o
c



1
 = ’ + u





 

VC
HT
t
2
%60;
1004
2






 ufor
u
T

%60
);100(log933.0781.1 10


ufor
uT
AG
W
H
wS
S
S


 S
SwS
W
WAGH
e


)(
0

1
2log
p
p
e
CC


 





HHVV
mV





 








'
''
log
1 vo
vo
o
c
c
e
C
HS







 








'
''
log
1 vo
vo
o
r
c
e
C
HS

 






 





















'
''
log
1'
'
log
1 p
vo
o
c
vo
p
o
r
c
e
C
H
e
C
HS




For NCC
For OCC
If OCC is loaded beyond σp’
)10(009.0  LLCC Cr CC  1.0
Terzaghi & Peck (1948)

8
CONCLUDED
REFERENCE MATERIAL
Principles of Geotechnical Engineering – (7th Edition)
Braja M. Das
Chapter #11
An Introduction to Geotechnical Engineering (2nd Edition)
By R. D. Holtz, W. D. Kovacs and T. C. Sheahan
Chapter #8 & 9

Geotechnical Engineering-I [Lec #20: Consolidation Settlement Computation]

More Related Content

What's hot (20)

Similar to Geotechnical Engineering-I [Lec #20: Consolidation Settlement Computation] (15)

More from Muhammad Irfan (20)

Recently uploaded (20)

Geotechnical Engineering-I [Lec #20: Consolidation Settlement Computation]