Peat Slides in Ireland – Causes and Prescriptions · Causes and Prescriptions Dr Mike Long & Dr...
Transcript of Peat Slides in Ireland – Causes and Prescriptions · Causes and Prescriptions Dr Mike Long & Dr...
Peat Slides in Ireland –Causes and Prescriptions
Dr Mike Long & Dr Noel Boylan*Dr Mike Long & Dr Noel Boylan*
UCD School of Architecture, ,Landscape & Civil Engineering(* Now UWA, Perth, Australia)( , , )
1st May 2009
Institiúid na gCóras Domhanda
An Coláiste Ollscoile Baile Átha CliathEarth Systems Institute
University College Dublin
Web: www.ucd.ie/earthEmail: [email protected]
DerrybrienDerrybrien and and PollatomishPollatomish 20032003Issue of landslides in Ireland highlighted by these slides in Autumn 2003Issue of landslides in Ireland highlighted by these slides in Autumn 2003Issue of landslides in Ireland highlighted by these slides in Autumn 2003Issue of landslides in Ireland highlighted by these slides in Autumn 2003
Irish Times30.10.2003
Irish Times24.10.2003
Irish Times24.10.2003
Irish Times30.10.2003Irish Times
30.10.2003
PollatomishPollatomish Landslide, Co. MayoLandslide, Co. Mayo
80mm rain in 2 hours+ 40 Failures over 5 kmc. 40 families evacuated, ,Structural damage Repair costs = €3 million
Irish Independent24.09.2003
Derrybrien, Co. Galway, Oct. 2003Photo courtesy
Dr. Paul JenningsAGEC
Ground EngineeringNov. 2003
Heavy rain before second movement phaseHeavy rain before second movement phaseSingle failure, travelling within stream valleySingle failure, travelling within stream valley
Gentle slopes, construction activitiesGentle slopes, construction activities
Photos courtesyKoen Verbruggen, GSI
No families evacuatedNo families evacuatedDamage to roads & bridgesDamage to roads & bridgesg gg g
Pollution & fish killPollution & fish kill
International Dimension NCE, 23/10/2003
(Van Baars, 2005)
Ground Eng., April, 2006
Response
• Formation of multidisciplinary Landslides Working Group (GSI)(GSI)
• Publication of “Landslides in Ireland” (2006) (Ed Ronnie Ireland (2006) (Ed. Ronnie Creighton, GSI)
• GSI landslides database (Charise Mc Keown, GSI)
• 148 events – 46 peat
• Both blanket / raised bog
Are these events unusual?
Lands o’erwhelmed with watery peatFrom Black Knock-laida’s bursting breast
Th B “R thli D i ti P ” (1820)Thomas Beggs “Rathlin a Descriptive Poem” (1820)
Events per century
30
35
25
at
slid
es
15
20
er
of
pea
5
10
Nu
mb
0
5
1400's 1500's 1600's 1700's 1800's 1900's 2000's
Quality of records?
Events per decade since 1900
14
16
10
12
14
at
slid
es
6
8
ber
of
pea
2
4
Nu
mb
0
Influence of climate change?
Events per year since 1991
6
7
4
5
at
slid
es
3
4
ber
of
pea
1
2
Nu
mb
0
Events per month
10
12
8
at
slid
es
6
er
of
pea
2
4
Nu
mb
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Data for 45 events only
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Fatalities
25
Castlegarde
20
liti
es
10
15
er
of
fata
Knocknageeha
5
10
Nu
mb
e
Erris
Knocknageeha
Lisdoonvarna
0
5 Lisdoonvarna
1708 1819 1896 1900
Knocknageeha, 1896
Cork Examiner 30/12/96
Feehan et al. (2008)
Robert Lloyd Praeger(1865 - 1953)
”It was dark cold weather, the Reeks were white with snow, the district a rather desolated one, and I well remember that feeling of depression with which we gazed at that black slimy mass stretching down the valley, somewhere in which lay entombed the bodies ofCornelius Donnelly his wife and six children”Cornelius Donnelly, his wife and six children ….
“Unwise turf cutting, by producing a high face without preliminary draining has frequently been the cause of these accidents. Such was so in the fatal Kerry case.”
Lloyd Praeger, R. “The way y g ythat I went” Figgis (1969)
Parallel events elsewhere
Verdal, Norway, 1893
Video clip
Causal factors I – external factors
Hi h i t it i f ll
Can these be linked to climate change?
• High intensity rainfall
• Long period of dry weather (cracks)
• Sudden loading due to construction
• Excavation in the peat e.g. turf cutting
• Historical land use (grazing, burning etc.)
Boylan et al. (2008)
Causal factors II – internal factors
• Slope inclination
• Peat thickness (NB: local depressions)• Peat thickness (NB: local depressions)
• Slope morphology
• Interface
• Hydrogeology (e.g. pipes, impermeable material b l t)below peat)
6
8
m) Intact6
8
m) Blanket Bog
2
4
6
Peat
Dep
th (m
IntactBlanket Bog
2
4
6
Peat
Dep
th (m
Blanket BogRaised Bog
0 10 20 30 40Slope Angle (Deg)
0
0 10 20 30 40Slope Angle (Deg)
0
(a) (b)
Peat thickness and slope angle at failure site(Boylan et al., 2008)(Boylan et al., 2008)
Recent peat slides in IrelandDate Area Mountain County
14/12/06 GleniffHorseshoe
Benwiskin Sligo
14/12/06 Clare Island Knockmore Mayo
31/12/06 Aasleagh Falls Bengorm Mayo
13/8/08 Geevagh Kilronan Sligo13/8/08 Geevagh Kilronan Sligo
22/8/08 Listowel Ballincollig Hill Kerry
23/9/08 Drumkerrin Corrie Leitrim
Factor No. of cases Comment
High intensity or prolonged
5 Climate change?or prolonged
rainfallchange?
Steep slopes 3
Construction 2Constructionactivities
2
Turf cutting 1
Clare Island -14/12/06
244.5 mm of rain in preceding two weeksSimilar event in 2000 and in the 1940’sWater supply to reservoir cut offWater supply to reservoir cut off
Rainfall
Bengorm, Co. Mayo – 31/12/06
Photos courtesyCáitriona Douglas
NPWS
Reactivated and caused road / bridge closure on N59 with 100 km diversion 19/7/07
Geevagh – 13/8/08 Photos from earlier event in 1984Photos courtesy Prof. Pete Coxon, TCD
38.7 mm or rain on 13th, 59.5mm or rain 13th – 15th
Persons trapped in houses/carsPersons trapped in houses/cars€200,000 damage to local football pitch and clubhouseMinor roads swept away, houses flooded
Ballincollig Hill, Co. Kerry – 22/8/08
21.1 mm rain on 18th
Bridge swept away, houses cut off, roads blockedRivers covered in peat telegraph poles knocked overRivers covered in peat, telegraph poles knocked overConstruction activities on site
Rainfall
EPA Report 28/4/09
Assessment of peat strength and stability UCD Civil Engineeringstability – UCD Civil Engineering• Quantitative assessment of risk of peat slides
• Planning Guidelines1 for wind farm developments • Planning Guidelines1 for wind farm developments require an assessment of peat stability to take place
zw
zInfinite Slope Stability Calculation
W
τ sFOS u=
βN
ββγ CoszSinFOS =
41≥FOS1DOEHLG (2006) Wind Energy Development Guidelines
4.1≥FOS
Need of a Model for Peat Strength
Two choices
Development of realistic (but complicated) model
Use of a more simple model for peat ( p )
of peat behaviour. Must account for at least:
•Fibrous nature of peat
p“strength”
•Gas•Interface strength•Peat hydrogeology
Roughe.g. field vane
More precisee.g. DSS
T-bar and Ball probes
High Quality Sampling
International research projectInternational research project on peat strength
UCD (Lab and field), TU Delft (+ESSM), NGI (sampling and in
it t ti )situ testing)
Sherbrooke block sampling of peat in the Netherlands by TU Delft, NGI, UCD, Dec 2006
UCD-DSS Apparatus
SpecimenAssembly
LoadingCup
Load Balance
100mm
UCD-DSS Apparatus 1
30
40
50
(%
)xy
0
0.5y/H
5
10
20
30
She
ar S
train
,
Engineering Shear Strain
Digital Camera
0
1
2.5
(
%)
i-max
In the xy plane, γxy
0
0.5y/H
1
1.5
2
Inc.
She
ar S
train
,
0
0.5
15
Max
.
Maximum Incremental Shear Strain γi-max
0.5
1
y/H
0
5
10
etric
Stra
in,
(%
)vo
l
Particle Image Velocimetry (PIV) software developed by White et al. (2003)
0
-15
-10
-5
Vol
ume
Volumetric strain, εvol
UCD-DSS … an example
spf = 9.8kPa
8
10(k
Pa)
6
ar S
tres
s
Matrix
4
onta
l She
a MatrixFailureInitiated,spm= 7kPa
0
2
Hor
izo
0 20 40 6010 30 50Shear Strain (%)
0
Field Testing
su-AVG ≈ su-DSS
Standard 10cm2
ConeCone
T-bar Penetrometer100cm2
Ball Penetrometer100cm2
Some conclusions
• Expect such events but plan for them• Expect such events but plan for them
• Produce susceptibility maps?
• More clearly understand link between rainfall and• More clearly understand link between rainfall and slides
• Geotechnical properties of materialsp p
Key UCD Message
• The Innovation Imperative: Productivity growth in the Irish economy has slowed to close to zero. The only way to rediscover productivity growth and be able only way to rediscover productivity growth and be able to sustain it is by innovation and the embedding of the knowledge society.
• The Energy and Climate Change Imperative: We have hugely demanding energy and emission reduction obligations – the only way to meet them is through the use of markets and innovation.
• The Earth Systems Institute response to these imperatives We will be an engine showing how to imperatives - We will be an engine showing how to use research and innovation – smart technology and smart policy - to regain competitiveness and productivity generate jobs and meet our energy and productivity, generate jobs and meet our energy and climate change obligations
Acknowledgements
Geological Survey of Ireland
Lankelma Ltd (UK)Lankelma Ltd. (UK)
François Mathijssen (TuDelft)
Paul Jennings AGECPaul Jennings, AGEC
George Cosgrave, UCD
Thanks for listening!
UCD Earth Systems InstituteMeeting the Challenge of Climate Change Meeting the Challenge of Climate Change
Seminar Series
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Marine Institute, Met Éireann, Sustainable Energy Ireland & Teagasc
Further details on the seminar series is available at www.ucd.ie/earth
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ESI email: [email protected]
UCD Earth Systems InstituteMeeting the Challenge of Climate Change Meeting the Challenge of Climate Change
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Friday 8th May 2009
Royal College of Physicians, 12.30pmRoyal College of Physicians, 12.30pm
Dr. Mark RichardsonUCD School of Architecture, Landscape & Civil Engineering
f fPerformance-based specifications: the key to optimising concrete’s contribution to the climate change
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