new conceptual model of large-scale landslidenew conceptual model of large-scale landslide reported...

New Conceptual Model of Large-Scale Landslide

Reported by

Chjeng Lun, Shieh

Director, Disaster Prevention Research Center

National Cheng Kung University

The Second Global Summit of Research Institutes for Disaster Risk Reduction Development of a Research Road Map for the Next Decade

March 19-20, 2015

National Cheng Kung University, The Department of Hydraulic and Ocean Engineering, TAIWAN

Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

梅姬M

egi typhoon

凡那比Fanapi typhoon

-2-

溫妮颱風(

53) Winnie typhoon

葛樂禮颱風(

63) Gloria typhoon

賀伯颱風(

96) Herb typhoon

畢莉颱風(

76) Billie typhoon

琳恩颱風(

87) Lynn typhoon

Chi-C

hi Earthquake

1950 60 70 80 90 2000 1999 05 07 04 08 01 09

象神颱風(

00) Typhoon Xangsane

艾利颱風(

04) Aere typhoon

納莉颱風(

01) Nari typhoon

海棠颱風(

05) Haitang typhoon

桃芝颱風(

01) Toraji typhoon

敏督利颱風(

04) Mindulle typhoon

聖帕颱風(

07) Sepat typhoon

馬莎颱風(

05) Masha typhoon

卡玫基颱風(

08) Kalm

aegi typhoon

辛樂克颱風(

08) Sinlaku typhoon

芭瑪Parm

a typhoon

莫拉克M

orakot

10 11

南瑪都N

anmadol typhoon

12 蘇拉Saola typhoon

Flooding Disaster Sediment Disaster LSL & MSD

To review historical disasters from 1950, LSL & MSD occur frequently.


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

-3-

Typhoon Morakot

• Path of the center of Typhoon Morakot

• The storm turned into a typhoon on Aug. 4. • Rainfall started on Aug. 6. • The eye of the typhoon left Taiwan from

Taoyuan at 14:00 on Aug. 8. • The rainfall continued until Aug. 10.


Case Study

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Experiment

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Conclusion

Background

-4-

Disasters of Typhoon Morakot Alisan Station

Long duration (91 hours) High intensity (123 mm/hour) Large accumulated rainfall depth

(3000 mm-72 hour) Broad extent (one-fifth of Taiwan was

covered)

• Sediment-related disasters in the mountain area located within the range of precipitation > 1,000mm

• Inundation area located at the downstream of rainfall center in the plain area


Case Study

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Experiment

Modelized

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Solution

Conclusion

Background

-5-

The relationship between accumulative rainfall and duration of catastrophic typhoons

Alisan Station


Case Study

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Experiment

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Conclusion

Background

-6- • Shieh, 2012


Case Study

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Experiment

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Background

-7-

The scale and type of the disaster increasing with the frequent appearance of extreme weather


Case Study

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Conclusion

Background

-8-

Large-scale landslide and compound disaster become a new challenge

Before Typhoon Morakot in Hsiaolin Village (FORMOSAT-2)

After Typhoon Morakot in Hsiaolin Village (FORMOSAT-2)

• Area：202 ha Depth：80 meter Volume： 24 million m3


Case Study

Idea

Experiment

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Background

-9-


Case Study

Idea

Experiment

Modelized

Comparison

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Conclusion

Background

-10-

LESSONS FROM THE DISASTER OF HSIAOLIN VILLAGE

• Compound Disaster, included shallow landslide, debris flow, flooding, large-scale landslide, natural dam break, occurred in Hsiaolin village

• The main disaster is caused by large-scale landslide.

Mitigation Strategies of Large-scale Landslide Disaster in Taiwan


Case Study

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-11-

Where Potential Area What Risk analysis (Influence Area) Why On-site monitoring When Forecast and Warning System Who Evacuation Plan How Training, Drills, Education

IDEA FOR MITIGATION STRATEGIES OF L.S.L. (6Ws1H)


Case Study

Idea

Experiment

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Conclusion

Background

-12-

On-site monitoring Forecast and Warning System

All the monitor result to setup the warning system, such as rainfall, groundwater level, surface deformation. How to combine all the result together?


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

1123.9mm 萬山

布唐布納斯溪 1399.8mm

A B

A

B

• To Review Landslide cases in typhoon Morakot, 2009

• Group A is classified as new born landslide, and group B include enlarge case and combine case

• New Born Case Cumulative rainfall >1,000 mm After rainfall peak near the turning point of accumulative

rainfall

• Enlarge & Combine case Cumulative rainfall is about 300- 500 mm Before rainfall peak

-13-


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

Case Study of Large-scale Landslide

in Taiwan

-14-

Definition of Large-scale Landslide Area > 10 ha Depth > 10 m Volume > 104 m3


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

• Fast-moving landslide was caused by typhoon.

• Hsiaolin Village, Kaohsiung County in 2009.

-15-

• Time：August/06-10 (Typhoon Morakot)

• Area of landslide：202 ha

• Depth of landslide：80 m

• Slope：𝟐𝟐°

• Movement Distance： 2000 m

• Accumulative Rainfall：2583 mm

• Loose soil mass

• With the imprint of groundwater


Case Study

Idea

Experiment

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Comparison

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Conclusion

Background

• Fast-moving landslide was caused by typhoon • Taimali River, Taitung County in 2009

-16-

• Time：August/06-10 (Typhoon Morakot)


• Depth of landslide：200 m


• Movement Distance： 1000 m

• Accumulative Rainfall：1400 mm

• Loose soil mass



Case Study

Idea

Experiment

Modelized

Comparison

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Conclusion

Background

• Slow-moving landslide was caused by rainfall • Lushan landslide, Nantou since 1994

-17-


• Depth of landslide：~100 m


• Mass movement


廬山地滑監測及後續治理規劃，黎明工程，2003


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

• Slow-moving landslide was caused by rainfall • Li-San landslide, Taichung, since 1990

-18-


• Depth of landslide：~50 m


• Movement Distance：800 m

• With the imprint of groundwater 中華水土保持學報，颱風降雨期間梨山地滑區邊坡穩定性之數值評估，2008


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

LIMI, 2003

Lushan landslide Hsiaolin Village(2009 yr.)

-19-

Large-scale Landslide (slow-moving landslide)

Shallow Landslide (fast-moving landslide)

Large-Scale Landslide (fast-moving landslide)

Occurrence: < 2 days(Typhoon Saola) without the groundwater layer

The Experimental Forest, NTU(2012 yr.)

p

S

2599.5 mm/hr

113

lope 22 ~

2 mm

29

i

P

φ ≈=

=

=

Occurrence: For decades with the imprint of groundwater

p

22 ~ 2730 ~ 35 mm/hr(2005~6 yr.)

820 mm (20

Slope 24 ~ 2

6

6

0 yr)

r

i

P

φ ≈=

=

=

Occurrence: 4 days (Typhoon Morakot) with the imprint of groundwater

p

21 ~ 25103 mm/hr

25

Slope 2

8 m

6

3 m

r

i

P

φ

=

=

≈=

Similarity of F.M.L and S.M.L.


Case Study

Idea

Experiment

Modelized

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Solution

Conclusion

Background

-20-

S.M.L F.M.L

Difference of F.M.L. and S.M.L.


Case Study

Idea

Experiment

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Solution

Conclusion

Background

-21-

(1 ) Net force acting on sliding block

(1 ) , where 1

D R FS D MaD dFSFS a FS tM dt

D dFSa tM dtdFSadt

− = − = =

⇒ − = − = ∆

⇒ = ∆

⇒ ∝

D: Driving Force R: Resistance Force M: Mass of sliding block

t∆dFS tdt

∆

𝐹𝐹 =𝑅𝐷

Safety Factor


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

• The flow velocity of infiltration and groundwater is usually small, therefore, what’s reason causes the rapid decreasing in F.S.?

• We are interesting in what kinds of interaction between infiltration and groundwater will trigger sudden failure or creeping landslide.

-22-


Case Study

Idea

Experiment

Modelized

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Conclusion

Background

-23-

0.85 m

Scale Pore water pressure gauge

Experiment measure data

sc

wb

: weight: porewater pressure

Wp

Gz

hz

GWz

Saturated Zone

Cavity Layer

Infiltration Layer

Water 0z

z

x

Air Flow

Seepage

Case I：Air escape from bottom

Gz

hz

GWz

Saturated Zone

Cavity Layer

Infiltration Layer

Water 0z

z

x

Air Flow

Seepage

Case III： Air escape from top

0.04 m


Case Study

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Experiment

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Conclusion

Background

-24-

Case I: Air escape from bottom

{ }{ }

s s w w

s s w

(1 ) ( ) ( ) tan cosS.F.=

(1 ) ( ) sin

where, 25 ; 30 ; 0.

c n L Sn h t p tn L Sn h t

c

γ γ ϕ θγ γ θ

ϕ θ

+ − + −− +

= = =

wp

tp


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

-25-

Anticipation of change in S.F.

Elevation controlling of groundwater

Scale Pore water pressure gauge

Anticipation of change in pore water pressure Case II: Groundwater upwelling

(Illustration)

wp

tp


Case Study

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Background

-26-

{ }{ }

s s w w

s s w

(1 ) ( ) ( ) tan cosS.F.=

(1 ) ( ) sin

where, 25 ; 30 ; 0.

c n L Sn h t p tn L Sn h t

c

γ γ ϕ θγ γ θ

ϕ θ

+ − + −− +

= = =

Case III: Air escape from top wp

tp


Case Study

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Experiment

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Conclusion

Background

• Develop the theory from physical phenomenon

-27-

ww w

aa a

0

(1 ) (1 ) 0

nS nSt

n S n St

ρ ρ

ρ ρ

∂+∇⋅

∂∂ −

+∇ ⋅ −∂

v =

v =

( )

( )

ww w w w

aa a a a

*ss s

+ +

(1 ) (1 ) + +

(1 ) (1 ) + +s s

DnS nS pDtDn S n S pDtDn nDt

ρ ρ

ρ ρ

ρ ρ

= ∇⋅ −

− = − ∇⋅ −

− = − ∇⋅

v g I f

v g I f

v g fσ

amp V RTM

=

Equation of mass conservation

Equation of momentum conservation

Equation of state

w s a 0+ + =f f f

Interaction among the constituents


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

• Convert the 3-D governing equation into 1-D.

• Interaction among the constituents in 1-D -the momentum supplies(interactions) can be divided into two parts

-28-

buoy

rel

: caused by the in the constituents surface

: the dra

normal pressure

relative veg force due to the tangential to the constituents sl urface ocity

ff

( )

( )

buoy w as

rel iw ias

1(1 ) (1 )

1

s

n Sp pnSf n nn z n z

p pf nS n Sz z

f

−∂ ∂= − − + − ∂ ∂

∂ ∂= + −

∂ ∂

buoy w ww

rel iww

w

(1 )(1 ) p pnS n Sf nn z n z

pf n Sz

f

∂ ∂−= − +

∂ ∂∂

= −∂

( )

( )

buoy a wa

rel iaa

1 (1 )(1 )

1

a

n S p pn Sf nn z n zpf n Sz

f

− ∂ ∂−= − −

∂ ∂∂

= − −∂


Case Study

Idea

Experiment

Modelized

Comparison

Solution

Conclusion

Background

• Governing equation in 1-D form

( ) ( )

( ){ } ( ){ }

w w w

a a a

0

1 1 0

nS nS ut z

n S n S ut z

ρ ρ

ρ ρ

∂ ∂+

∂ ∂∂ ∂

− + −∂ ∂

=

=

( ) ( ) ( )

( ) ( ) ( )

w w iww w

a a w iaa a

s s iw w ia as s

(1 ) (1 ) + 1 1

(1 ) (1 ) 1 1 1

Du p pnS nS g nSDt z zDu p p pn S n S g nS S n S n SDt z z zDu p p p p pn n g S n n S n nDt z z z z z

ρ ρ

ρ ρ

ρ ρ

∂ ∂ = − − + ∂ ∂ ∂ ∂ ∂

− = − − − − − − − −∂ ∂ ∂

∂ ∂ ∂ ∂ ∂ − = − − − + − − + − − − ∂ ∂ ∂ ∂ ∂

amp zA RTM

=

Equation of mass conservation

Equation of momentum conservation

Equation of state


Case Study

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Conclusion

Background

-30- wp

tp

sp

Case I: Air escape from bottom


Case Study

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Background

-31-

Case II: Groundwater upwelling

wp

tp

sp

wp


Case Study

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Conclusion

Background

-32-

wp

wptp

sp

Case III: Air escape from top


Case Study

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Background

-33-

Conclusion


Case Study

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Experiment

Modelized

Comparison

Solution

Conclusion

Background

•This model is a pilot study of LSL warning system in Taiwan . More field data are necessary before it is used.

•The moment of infiltration front touch with groundwater will induce fast-moving LSL.

-34-


Case Study

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Background

-35-

Don’t Touch !!

New Conceptual Model of �Large-Scale Landslideスライド番号 2スライド番号 3スライド番号 4スライド番号 5スライド番号 6スライド番号 7スライド番号 8スライド番号 9スライド番号 10スライド番号 11スライド番号 12スライド番号 13スライド番号 14スライド番号 15スライド番号 16スライド番号 17スライド番号 18スライド番号 19スライド番号 20スライド番号 21スライド番号 22スライド番号 23スライド番号 24スライド番号 25スライド番号 26スライド番号 27スライド番号 28スライド番号 29スライド番号 30スライド番号 31スライド番号 32スライド番号 33スライド番号 34スライド番号 35

new conceptual model of large-scale landslidenew conceptual model of large-scale landslide reported...

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