H.A.D. Samith Buddika11M51318

Geo- Environmental Engineering14 May 2012 1

What is Landslide ?

Movement of considerable mass of soil or rock along with the vegetation from higher elevation to lower elevation under thevegetation from higher elevation to lower elevation under the influence of gravity

http://en.wikipedia.org/wiki/Landslide

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Types of landslides Key component

Crown: Is the upper most part of the sliding terrain from where it is originated

Body: Sliding mass

Toe: lower most part of the landslide

Source: http://www.eoearth.org/article/Landslide3

Landslide vulnerability of Sri LankaTotal area of the Land : 65,000 km2

Area prone to landslides : 20 000 km2Area prone to landslides : 20,000 km

Annual Time Series Distribution of Landslides

Source : desinventar lkSource : desinventar.lk

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Landslides can be trigger by

Natural St f th hill l

Manmade Unplanned land use Steepness of the hill slope

Intensity of the precipitation Flood and reservoirs in hilly area

Unplanned land use Inappropriate construction methods Human intervention etcy

Deep weathering of rock materials and the depth of the weathered rock

Type of the rock materials

etc…….

Type of the rock materials Earthquake triggering factors etc……..

Landslides do not occur usually due to a single reason, but it is the net effect of several, process and factors, persisting for long period of time.

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Major Losses

Damage to life and property Damage to economical important facilities Damage to economical important facilities Damage to water, electricity and communication systems Effect on education and health Effect on education and health Transportation difficulties Et Etc…

Th d t th t l i t i i ibl dThe damage causes to the natural environment is irreversible and can not be estimated and perhaps will never be known.

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Landslides in Sri Lanka (Overall view)

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Effect of Monsoon pattern

Seasonal Distributions of Landslides

Rainy Seasons

http://www.urlaub-sr-lanka.info/sri-lanka-holiday/2012/02/weather-pattern-and-holiday-in-sri-lanka/

Rainy Seasons

South West Monsoon- May to August

North East Monsoon- November to FebruarySource : desinventar.lk

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According to Sri Lanka Building Research Organization

200 mm of precipitation within 3 days is suspeaciatable for landslides

Due to poor land use practice 75-100 mm for a 2 days period is sufficient to trigger landslides8

Human Interaction

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Flood and reservoirs in hilly terrain htt // b lk/ b/k l d /h d ht lhttp://www.ceb.lk/sub/knowledge/hydropower.html

1. Ground water level changed after flood2. Natural drainage patterns are charged3 Increase pore water pressure3. Increase pore water pressure 4. Accumulation of water in slopes5. Weight increase6 Landslide1. Scouring of river bank due to

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6. Landslidegflowing river

2. Loss of toe support

Impact of Vibration

There are no of earthquakes or volcanoes in Sri Lanka.

However, the failure of slopes associated with the up country railway is very common in Sri Lanka.

Source: R.M.S Bandara , National Building Research organization , g g

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People Affected Due to Landslides

Source : desinventar.lk

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No of Houses Destroyed and Damaged

Source : desinventar.lk

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Mitigation MeasuresGuidelines for Construction in

Landslide Prone Areas

D l id li f t ti d litDevelop guidelines for construction and quality assurance

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Mitigation MeasuresMitigation of Peradeniya Landslide

The applied structural mitigation measures include

Trimming and benchingRock blastingSoil nailingRock boltingC t ti f f d iConstruction of surface drainageTurfing

Project cost :

Rs. 87 Million

15http://www.nbro.gov.lk/web/index.php?option=com_content&view=article&id=173&Itemid=133&lang=en

Mitigation of Padiyapalella Landslide

Mitigation MeasuresMitigation of Padiyapalella Landslide

The applied structural mitigationThe applied structural mitigation measures include

Construction of retaining structuresConstruction of retaining structures Construction of surface drainage

Project cost :

Rs. 51.38 Million

16http://www.nbro.gov.lk/web/index.php?option=com_content&view=article&id=173&Itemid=133&lang=en

Mitigation MeasuresMitigation of Malhewa Rockfall

http://www.nbro.gov.lk/web/index.php?option=com_content&view=article&id=173&Itemid=133&lang=en

Mitigation structures consistingMitigation structures consisting

TrenchesBunds

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BundsFences

Recommendations

Landslide hazard zonation mapping

Landslide hazard identification and assessment of landslide risk

A li ti th d f l d lid i ti ti (l l it ) Application method for landslide investigations (local community)

Guidelines for construction and land use planning in hilly areas

Innovative methods for Landslide mitigation

Awareness and training programmes

Landslide early warning systems Landslide early warning systems

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