Webinar, TRB, June 2008 Sponsored by AFS40 Lining ...Webinar, TRB, June 2008 Sponsored by AFS40...
Transcript of Webinar, TRB, June 2008 Sponsored by AFS40 Lining ...Webinar, TRB, June 2008 Sponsored by AFS40...
Webinar, TRB, June 2008Sponsored by AFS40
Lining procedures and limit states for structural design
Ian D. Moore, PhD, PEng
GeoEngineering Centre at Queen’s-RMCQueen’s University, Canada
Summary
1. Stability of existing culverts2. Lining procedures3. Liner strength limits
– External fluid pressure– External earth pressure and vehicle
live loads4. References
Stability of existing culverts : structure
Deterioration characteristics are different for rigid & flexible culverts and so are the effects of the damage
Metal Culvert: Invert Rigid pipe: Longitudinal and waterline corrosion fractures: excess moment
Stability of existing culverts : erosion
Perforations or fractures allow water ingress and this can lead to soil erosion.Voids generally occur at the springline and they jeopardize both rigid and flexible culverts.
0
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0255075100
% t left
FOS Y
Cor
rode
d /
FOS Y
Inta
ct90o Invert Corrosion H=3.0m D=2m135o Invert Corrosion H=3.0m D=2m180o Invert Corrosion H=3.0m D=2m90o Invert Corrosion H=3.0m D=4m135o Invert Corrosion H=3.0m D=4m180o Invert Corrosion H=3.0m D=4m90o Invert Corrosion H=3.0m D=6m135o Invert Corrosion H=3.0m D=6m180o Invert Corrosion H=3.0m D=6m90o Invert Corrosion H=1.5m D=4m135o Invert Corrosion H=1.5m D=4m180o Invert Corrosion H=1.5m D=4m90o Invert Corrosion H=10m D=4m135o Invert Corrosion H=10m D=4m180o Invert Corrosion H=10m D=4m
Metal culvert deterioration
El Taher and Moore (2008) : stability againstyield (wall crushing) - decreases in proportion toloss of wall thickness (if zero soil erosion)
Rigid culvert deterioration
e.g. Concrete Pipe Culverti Joint leakage – ingress of
groundwaterii Erosion of backfilliii Less uniform soil supportiv Increased moments :
fracture accelerates erosion
Tan and Moore (2007) and Moore (2008) indicate thatdeformations infer the level of soil erosion
2. Lining procedures
• Slip-lining (insert preformed pipe & grout)• Cast in place pipe liner (resin-impregnated
tube pulled into place, inflated and cured)• Strip-winding (form tube in-place by
helically winding a strip, & grout)• Tunnel lining (assemble from plates etc)• Sprayed linings (concrete or polymers)
and others (sewer processes) : fold and form (a.k.a. deform-reform), swage-lining etc.
Lining procedures : Slip lining
Use any preformed pipe (metal, polymer, …)
Lining procedures : Cast-in-place lining
Felt impregnated with epoxy or other resinHot water, steam, or UV light curedCircular prismatic shapes easy; new techniquespermit non-circular and variable diameter liners
120” CMP CulvertPanel Lok IIIE
Lining procedures : Strip-wound lining
Polymer stripswelded, glued orlocked togetherGrout or reversewind to treat gap
Two dominant loads (“demands”)
1. External fluid loads• water in embankment
after high-water event• grout during
construction
3. Liner strength limits
ExternalPressure
FracturedHost Pipe
FlexibleLiner
Two dominant loads (“demands”)
2. External earth loads• overburden pressure
changes after lining• vehicle loads
DamagedCulvert
FlexibleLiner
Earth Load
3. Liner strength limits
ExternalPressure
FracturedHost Pipe
FlexibleLiner
Resistance
1. External fluid loads(water or grout)
> Controlled bybuckling strength
3. Liner strength limits
Buckling of cylinder under external pressure
0.01
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1.00
10 100DR (D/t)
Levy (1884)Pcr=3EI/R3
P cr/E
x10
3
0.01
0.10
1.00
10 100DR (D/t)
Aggarwal and Cooper (1984)
Levy (1884)Pcr=3EI/R3
7 x Levy(1884)
P cr/E
x10
3
Nonlinear: scatter due toimperfections
Old pipe increases stability – CIPP: ASTM F1216
Comparison with experiments
Effect of fractured pipe imperfections
OVALITY Rq : noncircular shape of fractured pipe
Δ
WAVINESS RΔ : liner waviness over invert
ASTM F1216 proposalMoore (2005,2008)Pcr = E (t/D)2.2 Rq RΔ
Effect of rigid pipe deformation on liner buckling strength
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10 30 50 70 90DRliner
RqR
Δ
ΔDH/D=20%
15%
12.5%
10%
7.5%
5%
2%
1%0.5
Moore (2008)
Resistance
2. External earth loads> Controlled by local effects(e.g. Law and Moore, 2003,7: bending in liner deforming within rigid pipe:vertical diameter decrease after repair) – notconservative designing liner as ‘new pipe’
3. Liner strength limits
0%
5%
10%
15%
20%
25%
30%
35%
40%
0% 2% 4% 6% 8% 10%
allowable strain
max
imum
thic
knes
s t/D
liner%
ΔDV/Dliner=20%
10%
7.5%
5%
3.5%
2%0.5% 1%
Moore (2008)
Effect of rigid pipe deformation: liner bending strength
Resistance – rigid pipe culvertsChoice of liner thickness
tmin to resist buckling <t selected <tmax to resist bending after installation
3. Liner strength limits
Relevant tasks• Verify strength of deteriorated
culverts• Develop culvert assessment guide• Establish earth load effects on liners
in metal culverts and concrete boxes• Develop culvert repair guide
NCHRP 14-19“Culvert Rehabilitation to Maximize Service Life
While Minimizing Direct Costs and Traffic Disruption”
ReferencesEl-Sawy, K. and Moore, I.D., 1997. Parametric study for buckling of liners:
effect of liner geometry and imperfections. Proc. Int. Con., Pipeline Division, ASCE, pp. 416-423.
El-Sawy, K. and Moore, I.D., 1998. Stability of loosely fitted liners used to rehabilitate rigid pipes. Journal of Structural Engineering, ASCE, Vol. 124, No. 11, November, pp. 1350-1357.
El Taher, M. and Moore, I.D. 2008. Finite element study of corroded metal culvert stability, Transp. Res. Board Annual Conf. (accepted TRR).
Law, T.C.M., and Moore, I.D., 2007. Numerical Modelling of tight fitting flexible liner in damaged sewer under earth loads, Tunneling and Underground Space Technology, Vol. 22, (2007), p. 655-665.
Law, T.C.M and Moore, I.D. 2003. Response of repaired sewers under earth loads, Transp. Res. Record, No. 1845, pp. 173-181.
Moore, I.D., 2005. "Buried Infrastructure Repair Using Liners : Construction Techniques, Structural, And Geotechnical Issues”, 11th Int. Symp. on Structural and Geotech. Eng., Cairo, Egypt.
Moore, I.D. 2008. Keynote. Pipe rehabilitation: effect of damage to existing pipes and design of pipe repairs, Trenchless Australia 2008, 7th National ASTT Conf. and Exhibition, 2-5 March, 12pp.
Tan, Z. and Moore, I.D. 2007. Effect of backfill erosion on moments in buried rigid pipes, Transp. Res. Board Annual Conf. Washington 29pp.