ppt kvasnicka domitrovic

8/12/2019 Ppt Kvasnicka Domitrovic

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Seismic analysis of the reinforced earthwall Strikici at the highway

Zagreb-Split-Dubrovnik

Kvasnicka, P., Domitrovic, D.,University of Zagreb, Faculty of Mining Geologyand Petroleum Engineering


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Reinforced earth (RE)contents- Introduction- RE - internal stability- RE - external stability

- RE - seismic analysis- Testing and monitoring- RE and Eurocodes- Conclusion


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Reinforced earth what is it?


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RE wall Strikici

Croatia

A d r i a t i c s e a


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RE-wall Strikicimax. height 26,8 m, length cca 600 m

- crossection withstrips


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paraweb strip

Consists of discretebundles of closelypacked high strengthsynthetic fibres, lyingparallel to each other,encased in a toughand durable polymericsheath.


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HYPOTHESIS OF CALCULATION FOR

INTERNAL STABILITY (statics)according to the AFNOR standard NF P 94-220-0/1 t

p

HpHp

0,3 H m

tm

tp

tensiont

Resistantzone

Line of maximum tension

La: Adherence length

Tension along a reinforcing strip

Active zoneFacing 10

3


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CALCULATION FOR INTERNAL STABILITY statics - results

- forces in strips at crossection with max height, 26,8 m.

677,731,2736,6724,8

638,232,36,536,6724,0

499,733,96,236,6720,0

374,132,2436,6716,0

302,434,82,536,6712,0206,627,3227,508,0

141,217,4218,334,0

20,24,7218,330,4

pull outforce, T f

[kN]

max.tensionforce, T max[kN]

numberof strips

per m

design stripstrength

[kN]

depth z,from top

[m]


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Engineering-geologic description of rock

mass (karst region): Well stratified rudist upper cretaceous limestones.

Rock mass - system of joints with relatively large apertures,from 1 to 5 mm. Apertures are partially filled with clay anddebris. Blocky and irregular (thetraedron) blocks, mainlymeter-sized, are bounded by systems of joints.

The elements of the systems of joints were surveyed as wellas the other data required for categorization of rock mass forthe purpose of calculation of the geologic strength indexes

(GSI) for each weathering zone. JRC = 8 - 10, GSI: 49 54;


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EXTERNAL STABILITY

Stability of rock-slope with reinforced

earth wall:The slope inclination varies between

20 o and 30 o, while the slope angle of

joints varies from 20o

to 23o

in therock mass in the same direction.Shear plains in the rock mass have the

same inclination as the slope =>unfavorable


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Numerical model (Plaxis)

Sliding plane 1

Sliding plane 233 0

-66 0


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Crirical failure surface, PLAXIS, Phi-c-reduction, Fs = 1,75

Reinforced fill -HS model

Rock mass - Jointed rock model :

q = 20,0 kN/m 2


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Seismic analysis

Plaxis-dynamic


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56,0075,274,915.05.2002 .Gilroy62,31761,47,6

13.01.2001 .El Salvador

Time [s]Max. akceleration [cm/s 2]MagnitudeDate

Seismic load - two accelerograms


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Checking the influence of model boundariesto calculation results - models

+++ 60Model 3

+++ 20Model 2

++0Model 1(benchmark)

MagnitudeMw=7,6

MagnitudeMw=4,9

boundarydistance

[m]Name


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Model 1 (benchmark model)Model 2Model 3

Point A

Point B

Point A

Point B

Point A

Point B


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Acceleration at point A, Mw = 4,9

0,52 m/s 2

0,35 m/s 20,42 m/s

2


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4,9 m/s 2

6,4 m/s 2

5,0 m/s 2

Acceleration at point A, Mw = 7,6


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Forces in strips, Mw= 4,9

0 50 100 150 200 250Tensile force in strip [kN]

0

10

20

30

40

S t r i p l a y e r n u m

b e r

Magnitude 4,9Model 1Model 2Model 3Static modelStatic tensile strength

Magnitude 4,9


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0 100 200 300Tensile force in strip [kN]

0

10

20

30

40

S t r i p l a y e r n u m

b e r

Magnitude 7,6Model 1Model 2Model 3Static modelStatic tensile strength

Magnitude 7,6

Forces in strips, Mw= 7,6


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Wall facing displacement, Mw=4,9

-1.6 -1.2 -0.8 -0.4 0Wall facing displacement [cm]

0

5

10

15

20

25

W a l l h e i g h t [ m ]

Magnitude 4,9Model 1Model 2Model 3

Magnitude 4,9


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-120 -80 -40 0 40Wall facing displacement [cm]

0

5

10

15

20

25

W a l

l h e i g h

t [ m

]

Magnitude 7,6Model 1Model 2Model 3

Magnitude 7,6

Wall facing displacement, Mw=7,6


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Influence of model boundaries to calculationresults :

Mw = 4,9 small influence to values of horizontaldisplacements and tension forces in strips

Mw = 7,6 great influence to values of horizontaldisplacements and tension forces in strips

influence of boundaries increases with earthquakemagnitude


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Construction


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RE material => crushed stone (insitu)

Max. diameter 25 cm

no clay particles


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Construction of drainage and firstpanel layer


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putting panels in place


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paraweb strips and channel forreinforcement


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facing


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Material testing and monitoring


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Testing the strips(University of Zgb. )

0

5

10

15

20

25

30

35

40

45

50

55

60

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Relativna deformacija (%)

S i l a

( k N )

50 kN/1 50 kN/2 50 kN/3

Fmax 1 =56,09 kN Fmax 2 =55,72 kN Fmax 3 =56,62 kN

EA = 501,0 kN


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Geophysical measurements

MASW => measurements of v p i vs Calculating geophysical moduli: Young

(E), shear modulus (G), bulk modulus (K)Poissons ratio () =>

Checking soil densification


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KARAKTERISTI NI PRESJEKREFRAKCIJSKOG PROFILAOKOMITOG NA OS AUTOCESTE

RASJEDNA ZONASA KAVERNAMA ISPUNJENIM GLINOM I KRJEM

KOMPAKTNA STJENOVITA MASA U PODLOZI


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Longitudinal crossection of Strikici RE wall


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Measurements of horizontaldisplacements with deformeter


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Monitoring deformeter positions

SR1IX_1 18,50 m

SR1IX_2 16,50 m

PK 9+850

SR1IX_3 21,00 m


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Measurements of horizontaldisplacements with deformeter

Metal rings outside plastic tubes et 1,0 m distance LVDT Linear Variable Differential Transformer

Prsten A Prsten B

Prsten A Prsten B


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Tube installation.

Measurement at RE wall Striki i.


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Reinforced earth (fill) and EurocodesEN 14475 (Jan. 2006), BS: Execution of special geotechnical works:

reinforced fill (RF) TC CEN/TC, held by AFNOR. EC7 does not cover the detailed design of RF structures. Values of

partial factors and load factors in EN 1997-1 have not been calibratedfor RF, but there is many common features.

Two stage approach has been adopted for the development ofstandards for RF:

Working group 9 was mandated by TC288 for producing guidance onthe execution of RF, before working towards common method ofdesign (EN 14475). Scope: earth retaining structures reinforced steep slopes with facing embankments with basal reinforcement and reinforcement against frost

heave in the upper part.


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ConclusionRE walls are suitable for karst regions

because: high ground bearing capacity, milled in situ

material (balance the cut and fill quantity),simple construction, reasonable price environmentally acceptable

stable in seismic active regions


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M O L T O

M O L T O G R A Z I E !

G R A Z I E !

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