load reduction and arching
DESCRIPTION
arcos reduccionTRANSCRIPT
Load Reduction and Arching on Buried Rigid Culverts
Using EPS Geofoam.
Instrumented Field Tests and Design Method
Jan Vaslestad, NPRA, [email protected]
Murad S. Sayd, NPRA, [email protected]
Tor H. Johansen, NPRA, [email protected]
Louise Wiman, NPRA, [email protected]
What is the imperfect ditch method?
Instrumented field installations from Canada, USA and
China
Four instrumented field installations from Norway
Design method
Comparison of measured earth pressure with design
method
Conclusion
Imperfect Ditch Method
Imperfect Ditch Method (induced trench)
Measured earth pressure from previous studies on fill without compressible material
Full-scale test with sawdust as compressible material(McAffee and Valsangkar, Can. Geotech Journal 45: 85-101, 2008 )
Full-scale test from Kentucky Transportation Center using EPS Geofoam
(Hopkins and Sun, Univ. of Kentucky Transportation Center Geotechnology, 2007)
Full-scale test from Kentucky Transportation Center using EPS Geofoam
(Hopkins and Sun, Univ. of Kentucky Transportation Center Geotechnology, )
Full-scale test from China(Jiang and Gu, 2nd int. conf. GEDMAR08, Nanjing China, 2008 )
Field Installation
Eidanger, 1988
EPS
1600 mm
Cell 2 Cell 3
Cell 1
Sandy gravel (0-16) mm
1950 mm
500 mm
500 mm
1000 mm
Cell 4H=14.0 m
Earth pressure cell
Settlement tube
Rock fill
2000 mm
LEGEND:
-150
-100
-50
0
50
100
150
200
250
300
01
.01
.19
88
01
.01
.19
92
01
.01
.19
96
01
.01
.20
00
01
.01
.20
04
01
.01
.20
08
Time [ date ]
EP
S d
efo
rm
ati
on
[m
m]
Ea
rth
press
ure [
kP
a]
Cell 2- measured
cell 2 - calculated
overburden
Measured deformation
of EPS block
Field Installation
Sveio, 1989
EPS
1400 mm
Cell 1 Cell 2
Cell 4
Sandy gravel (0-16) mm
1710 mm
H=15.0 m
Earth pressure cell
Settlement tube
Cell 3
Cell 5
200 mm
500 mm
1000 mm
3000 mm
Rock fill
Top of embankment
Dense moraine
LEGEND:
-200
-150
-100
-50
0
50
100
150
200
250
300
350
01.0
1.1
990
01.0
1.1
995
01.0
1.2
000
01.0
1.2
005
01.0
1.2
010
Time [date]
EP
S d
efo
rm
ati
on
[m
m]
E
arth
pre
ss
ure
[ k
Pa
]
Cell 1 measured earth pressure
Cell 2 measured earth pressure
Calculated overburden Cell 1 and
cell 2
Deformation of EPS block
Field Installation
Hallumsdalen, 1989
EPS
2.0 m
Cell 2
Silty clay
Cell 1
1.0 m
0.5 m
0.3 m
0.3 m
0.2 m
0.4 m
1.85 m
Silty clay
case a) with EPS block
plateSettlement
Silty clay
Cell 3
Silty clay
case b) without EPS block
2.55 m
rodSettlement
Siltyclay
H = 10.8 m H = 9.8 m
-300
-200
-100
0
100
200
300
01
.01
.19
89
01
.01
.19
94
01
.01
.19
99
01
.01
.20
04
01
.01
.20
09
Time [date]
EP
S d
efo
rm
ati
on
[m
m]
e
arth
press
ure
[kN
/m2
]
Cell 1 measured Earth
pressure (with EPS)
Deformation of EPS
block
Cell 1 calculated
overburden
Cell 3 -measured earth
pressure (without EPS)
Cell 3 calculated
overburden
Field Installation
Tømtebekken, 1992
EPS
Compacted bed
1730 mm
H=22.0 m
Earth pressure cell
300 mm
500 mm
2750 mm
Top of embankment
LEGEND:
400 mm
164 mm 1400 mm Cell 4
Cell 2
Cell 1
Cell 7
Cell 5
Cell 6
Cell 3
-200
-100
0
100
200
300
400
01
.07
.91
01
.07
.95
01
.07
.99
01
.07
.03
01
.07
.07
01
.07
.11
Time [day]
Defo
rmati
on
of
EP
S [
mm
] E
art
h p
ressu
re [
kP
a]
Cell 1 calculated overburden
Cell 2 calculated overburden
Cell 2 measured earth pressure
Cell 1 measured earth pressure
Deformation of EPS block
Concrete pipe before backfilling, Tømtebekken 1991
Concrete pipe with hydraulic earth pressure cell, Tømtebekken 1991
Settlement plate on EPS, Tømtebekken 1991
Placing EPS above the pipe, Tømtebekken 1991
Full-scale test from China(Jiang and Gu, 2nd int. conf. GEDMAR08, Nanjing China, 2008 )
Measured earth pressure from field
installations
0
50
100
150
200
250
300
0 5 10 15 20 25
Fill height above the culvert [m]
Ver
tical
ear
th p
ress
ure
[kP
a]
Tømtebekken
Hallumsdalen
Eidanger
Sveio
Shannxi, China
Calculated
overburden H
Design Method-Arching factor
(1990)N H vertical earth pressure AfterVaslestadv A
1 A
A
eN arching factor
A
2 v
HA S
B
tan (1976)v AS r K frictionnumber after Janbu
Comparison with Design Method
0,00
0,20
0,40
0,60
0,80
1,00
0 3 6 9 12 15
Normalized height of cover [H/B]
No
rma
lize
d e
art
h p
res
su
re, N
A =
v/
H
Tømtebekken
Eidanger
Sveio
Calculated for r=0,7
Calculated for r=0.8
Calculated for r=1.0
Shannxi, China
Summary of measured field installations
Site
Culvert type H/B Arching
factor
NA measured
in the field
Thickness
of
EPS block
Backfill
TypePipe Box
Eidanger 7 0.24 0.50 m Rock fill
Sveio 8.8 0.22 0.50 m Rock fill
Tømtebekken 13 0.22 0.50 m Rock fill
Hallumsdalen 7.5 0.5 0.50 m Silty clay
Shannxi, China
(Gu and Jiang)
4.5 0.28 0.30 m ‘Silty soil’
New Brunswick, Canada
(McAffee and Valsangkar)
9 0.24-0.35 0.58 m of
sawdust
Coarse
rock fill
Canada model(McAffee and Valsangkar)
8.8 0.38 thin layer Silica
sand0.24 design
thickness
Centrifuge model test with EPS block as compressible material
(McGuigan and Valsangkar, Can. Geotech Journal 47: 85-101, 2010 )
Centrifuge model test with EPS block as compressible material
(McGuigan and Valsangkar, Can. Geotech Journal 47: 147-163, 2010 )
Numerical modeling of field test with FLAC (McAffee and Valsangkar, Can. Geotech Journal 45: 85-101, 2008 )
FEM modeling of load reduction using EPS
block of varying thickness from China(Jiang and Gu, 2nd int. conf. GEDMAR08, Nanjing China, 2008 )
Handbook 016: Recommended procedure for installation of imperfect ditch culvert with EPS
•Easy to specify material characteristics using EPS
•No decomposing of EPS like the organic material
•Easy to install the EPS, controlled geometry
•Reducing vertical earth pressure to 22 to 28 % of overburden in
granular material, and around 50 % in cohesive material
•Long-term earth pressure measurements shows the arching effect is
stable over time using EPS
Conclusion
Thank you for your attention!
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