Developing an *engineering approach* to

Report
Developing an “engineering approach” to
design and selection of lining systems for
irrigation canals.
Part 1 - Analysing results of long term trials to understand
failure modes of canal lining systems.
2012 IAL Conference Adelaide
By
Nick Kastoumis BEng Civil
Geosynthetics Consultant
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
1
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
1.
•
•
•
•
Why do we need this presentation ?
The size of water conservation expenditure is huge
A lot of systems on the market – how do we assess them?
Long service life requirements + 25yrs
Conserving water is vital - getting it wrong - is very costly
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
2
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
2.
The objectives of this presentation – 5 goals
1. Educate decision makers on the body of knowledge available
2. Identify forces in canals and liner failure mechanisms - through analysis
3.
4.
of these trials
Prompt designers and decision makers to consider these forces
when selecting a lining system
Call out to other organisations to share experiences with canal lining
5. Find funding for research into quantifying the forces and developing an
engineering approach to canal lining design
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
3
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
3.
The 2 main reports that were looked at
1. 1991 – Deschutes Canal Lining Demonstration Project; USBR
2. 1999 – Evaluation of canal lining projects Rio Grande; TWRI
Also considered
• 2004 – Open Channel Seepage and Control – Guidelines by
ANCID
o
o
o
o
Done in Australia
3 year period of trials
Installation procedures were assessed
Long term durability was not assessed – would like to follow up with
these irrigators to get updates on performance !!
• 1984 - Performance of plastic canal liners – PVC and HDPE
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
4
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
4.
1991 - Deschutes canal lining Demonstration Project
• Funded by USBR – United States Bureau of Reclamation
• 34 different lining systems were trialled , installed from 1991
o exposed membranes (16)
o Armour/covered systems (11)
o Spray ons (7)
• Lining systems were evaluated/followed up
•
•
•
•
During installation
7yrs on in the 1999 7yr Report
10yrs on in the 2002 10yr Report
2011 I have emailed the irrigations districts for feedback on
performance
• Some 20yr old coupon samples have been taken and tested in 2011
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
5
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
1991 - Deschutes canal lining Demonstration Project
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
6
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
5.
1999 – Evaluation of Canal Lining Projects in Rio Grande valley
• Conducted by TWRI – Texas Water Research Institute
• Two stage of trials and reports were published
• TR353 – 2009 Report
o 6 different liners were installed in 1999
o PET, PVC, PP, EIA-R, EPDM, PU
o Performance was evaluated after 10yrs
• TR412 – 2011 Report
o Follow up on previously evaluated liners from 2009 , now 12yrs old
o New liners were trialled , TPO-R, EPDM-R, PP-R
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
7
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
1999 – Evaluation of Canal Lining Projects in Rio Grande valley
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
8
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
6.
Identifying forces on canal liners
1. Point out an anomaly
• We are good at designing liquid containment
o Dams, ponds, reservoirs , lagoons, even landfills
o We usually get some leaks
o Complete system failure is rare
• When it comes to canal liners we have much more failures even complete
removal
• But its not some “aggressive liquid”
• Its ONLY WATER!!!!!
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
9
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Question:
Why do we continue to
design canal liners as if
they are pond liners ?
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
10
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
7.
Forces acting on canal liners vs. pond liners
Liquid containment
Liquid transportation
Dams, ponds, reservoirs, lagoons
Canals , channels
UV and weathering
Exposed areas must resist UV and
weathering
Exposed areas must resist UV and
weathering
Hydrostatic forces
Can be very deep, >3m so puncture is
one of the main failure mechanism of
containment liners
Generally shallow < 3m so subgrade
puncture resistance is not important
to consider
Hydrokinetic forces
Generally only considered for the inlet
and outlet structures , spillways
The main failure mechanism of
flexible canal liners
Mechanical damage
Can be avoided by fencing or
armouring of the liner and or prompt
repairs
Can be avoided by fencing or
armouring of the liner and or prompt
repairs
Forces to resist
Abrasion
Must be considered for the life of the
Generally only considered for the inlet
lining system, including any armour or
and outlet structures , spillways
coverings
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
11
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
The moment when the light bulb went on
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
12
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
8.
All of these Canal lining reports – support tearing
and abrasion as the most important failure
mechanisms of canal liners
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
13
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
9.
How did the exposed liners go ?
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
14
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
How did the exposed liners go ?
This is puncture - Hypalon shows excellent puncture resistance. The
puncture has NOT progressed for 4 yrs. pg. 94 Deschutes 7yr report
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
15
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
But, unable to resist tearing
Hypalon suffers severe Tear
Damage: 0.9mm Hypalon + geotextile 7yrs old – pg. 96 Deschutes 7yr report
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
16
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
This is NOT a PUNCTURE, this is a TEAR - Severe Tear
Damage: 2mm textured HDPE after 6 ½ yrs. service – pg. 87 Deschutes 7yr report
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
17
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
This is NOT a PUNCTURE, this is a TEAR Severe Tear
Damage: 1.14mm unreinforced EPDM rubber, less than 8yrs service – pg. 16 TWRI Report
2008
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
18
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Life prediction of exposed liners – be careful !!
Table 13.-Coupon Testing of Exposed Geomembrane test sections . From Deschutes 10yr Report pg 191
Section
Material
Age
Visual
Assessment
Physical Property
Testing
Service Life
Prediction
A~3
80-mil Textured
HOPE
10 years
Excellent
Elongation down 90%
OIT down 30%
20-25 years
A-4
30-mil PVC with
Bonded
Geotextile
10 years
Very Good
Tensile up 30%
Modulus up 140%
Elongation down 70%
10-15 years
A-5
45-mil Hypalon
10 years
Fair to Poor
Tear strength down 60%
10-15 years
A-6
36-mil Hypalon
10 years
Fair
Tear strength down 60%
10-15 years
0-3
45-mil EPDM
2 years
Excellent
Elongation down 30%
Tear strength down 50%
15-20 years
0-4
30-mil LLDPE
2 years
Excellent
Tensile down 10%
Tear Strength down 10%
10-15 years
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
19
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Life prediction of exposed liners – be careful !!
Table of lining performance. TWRI Report TR412 pg 13
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
20
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Life expectancy vs Tear , is there a correlation ?
Tear strength of some geomembranes used in Deschutes
and TWRI canal lining trials
600
500
Tear Strength (N)
400
300
200
100
0
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
21
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
10.
How did the spray on liners go?
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
22
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
How did the spray on liners go?
Some points on membranes spray applied to geotextile
• I have worked with some spray on membranes and even failed at developing my own
• The main problem is LACK OF SATURATION
• The liquid is made up of 2 parts
o Solvent – the carrier
o Solids – the final membrane
• 2 main plains of failure
o Bonding to substrate – does not occur
o Solvent penetrates geotextile but solids remain on the top
o No solids saturate the geotextile. The result is
 Thin bonding interface between film and geotextile
 Porous surface of 3D geotextile
• Solids must saturate the geotextile to take advantage of its mechanical
strength !!
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
23
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
11.
How did the covered liners go?
There were 4 types of cover
1. Unreinforced shotcrete
2. Reinforced shotcrete
3. Grout mattresses
4. Soil – we wont cover this here
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
24
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Unreinforced shotcrete - main failure mechanism of unreinforced shotcrete
was cracking – typical of local settlements and inconsistent thickness
Photograph 122.— Importance of Tensile strength. Close up of 300mm diameter hole in
shotcrete lining. Shotcrete is less than 25mm thick.
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
25
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Reinforced shotcrete - main failure mechanism of fibre reinforced shotcrete
was cracking – typical of shrinkage and inconsistent thickness
Importance of flexibility. Transverse crack is running all the way across the channel
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
26
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Grout Mattresses - main failure mechanism of grout mattresses is abrasion
Photograph 103.— Severity of abrasion in canals. Geotextile is deteriorated by
abrasion. Note that some of the grout bricks are also missing in this area.
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
27
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
12.
In summary
Next time you consider a lining system for a canal, past experience shows that to meet long
term durability requirements
1. Exposed membranes – need to be assessed for
o abrasion and tearing strength
o UV and weathering
o For the whole service life !!
2. Amor and cover systems have issues too
• Shotcrete lacks flexibility so a designer must consider
o subsurface drainage
o Long term differential settlement
• Grout mattresses must consider
o long term abrasion
3. Spray on membranes – are yet to be proven as long term effective lining systems
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
28
Developing an “engineering approach” to design and selection of lining systems for
irrigation canals
Thank you
Any questions ?
[email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA
29

similar documents