INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

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INDIATEESTA DAM

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INDIATEESTA DAM

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INDIATEESTA DAMGeneral Presentation

LOCATION : Sikkim

RIVER : Teesta

TECHNICAL FEATURES :

- Concrete Gravity Dam, 9.5 m dia, 17.78 km long Head Race Tunnel.

- Height of dam from deepest = 96m

- Length of crest dam = 183m

HYDRO POWER GENERATION

Underground power house

- Capacity 510 MW (3 x 170 MW)

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INDIA - TEESTA DAM

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INDIATEESTA DAM

Cutoff

GENERAL SCOPE OF WORKS

- 2 Cofferdams Upstream / Downstream to protectthe Dam pit from the monsoon floods

- Construction of a cut-off below each cofferdam

GROUND CONDITIONS

Permeable bouldary material encountered down to 50m deep

Bedrock mainly composed of quartzo - phyllite ( 70 - 120 Mpa )

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INDIATEESTA DAM

Cut - off wall / Permeation grouting

CUT-OFF ELEVATION

TEESTA DAM PROJECTUPSTREAM COFFER DAM(NHPC)

NOTERock fissure grouting below the jet grout cut-off wall:To be decided by the Engineer after the Lugeon tests to be carried out below the cut-off wall

ROCK PROFILE(EXPLORATORY HOLES)

subject to NHPC dierctive

base of the clay core

LEFT BANK

25/10/2002

WORKING PLATFORM

DDH06 - DDH07 : PREVIOUS GEOLOGICAL INVESTIGATION HOLESA1 - A7 : EXPLORATORY HOLES

EL:540.00

NOTE

TOP OF JET GROUT CUT-OFF EL:539.00

DDH06

A A2

A1

A3 A4 TEESTA RIVER A5

1

LEGEND:

802503 -

DDH07A7A6

B

RIGHT BANK

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INDIATEESTA DAM

Cut - off wall / Permeation grouting

2

FALL = 1.5%

TOP OF JET GROUT CUT-OFF EL:539B

DDH09

D1A

WORKING PLATFORMEL: 543.00

C

ROCK PROFILE(EXPLORATORY HOLES)

LEGEND:

ED

WORKING PLATFORMEL: 544.00

LEFT BANK

TEESTA DAM PROJECTDOWNSTREAM COFFER DAM

CUT-OFF ELEVATION (solution 2) angular cut-off

TYPICAL PIEZOMETRICAL LINE

TOP OF JET GROUT CUT-OFF

ROAD SAVED WITH THIS "ANGULAR" SOLUTION

AREA OF JET GROUT CUT-OFF WALL: 2797 m²

D4

A

TEESTA RIVERD3

WORKING PLATFORMEL: 535.00

D1D2

EL:534

1

RIGHT BANK

TOTAL LENGTH = 141.64 mDIMENSION D to E = 9.89mDIMENSION C to D = 33.75m

NOTED1A- D4 : EXPLORATORY HOLES

DIMENSION A to B = 58.77mDIMENSION B to C = 39.23m

DDH09 : PREVIOUS GEOLOGICAL INVESTIGATION HOLE

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TEESTA DAM (Works Site)

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INDIATEESTA DAM

Cut - off wall / Permeation grouting

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INDIA - TEESTA DAM

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INDIA - TEESTA DAM

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

JET - GROUTING WORKS

= PRE - DRILLING + JETTING

- 7000 m2

- Maximum depth = 70m

- Diameter of columns = 120cm to 260cm

- Average deviation = 1,5 %

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

PERMEATION GROUTING

Systematic complementary treatment

- 1 line at 1.2m spacing

- Systematic first phase of grouting BC + Gel

- Final phase based on the following factors :

- results of the first phase

- deviation and diameter of the jet columns

- deviation of the grout holes

- mapping of the boulders

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

ROCK GROUTING

- Rock permeability to be investigated

- Grouting with stable mix Bentonite / Cement to beperformed according to the investigation

SPECIFIED SEEPAGE CRITERIA

Global specified permeability of the cut - off wall

K = 1 x 10-6 m/s

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

INTAKE

EXISTING HAUL

A

B

A5

B

DDH07A7

A6

A4

A3

A2

A1

DDH06

TEESTA RIVER

N

ROAD MIN. EL:555

UPSTREAM COFFER DAMTEESTA DAM PROJECT

PLAN VIEW

B

PZ

PZ

PZ

PZ

PZ

PZ

PZ

PZ

PZ

PZ

PZ

PZ WP

WP

WP

WP

WP

US Plan view

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

CROSS SECTION 1-1

TEESTA DAM PROJECTUPSTREAM COFFER DAM

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

A

DOWNTREAM COFFER DAMTEESTA DAM PROJECT

PLAN VIEW(solution 2) Angular cut-off

1

2

TYPICAL PIEZOMETRICAL LINE

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INDIATEESTA DAM

Jet - grouted cut - off wall / Permeation grouting

CROSS SECTION 1-1

(solution 2)DOWNTREAM COFFER DAMTEESTA DAM PROJECT

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INDIA - TEESTA Upstream Cofferdam

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INDIA - TEESTA DAMPlot Test Site

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INDIATEESTA DAM

Shaft in plot test

INDIA INDIA -- TEESTA TEESTA -- Double Jet air+grout usedDouble Jet air+grout used

HP GROUTHP GROUT

LP GROUTLP GROUT

HP WATERHP WATER

Double jet ( HP water + LP grout )

Single jet ( HP grout )

air

airDouble jet (HP grout

ENCAPSULATED by air )

HP GROUTHP GROUT

Triple jet (HP water ENCAPSULATED by air + LP grout )

HP WATERHP WATER

LP GROUTLP GROUT

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INDIA - TEESTA DAM (Diversion Tunnels)

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INDIATEESTA DAM

Works Site

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INDIA - TEESTA DAM Works Site

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INDIA - TEESTA DAM

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INDIA - TEESTA Secondary Column Diameter

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INDIA - TEESTA Upstream Cofferdam

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INDIA - TEESTA Upstream Cofferdam

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INDIA - TEESTA Downstream Cofferdam

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INDIA - TEESTA Average Final Pressures and Volumes

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INDIATEESTA DAM

Image from PICODI

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INDIATEESTA DAM

Pumping test

Upstream

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INDIA - TEESTA DAM

Leakage discharge calculation with PLAXIS

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INDIA - TEESTA DAM (Dam Pit Excavation)

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INDIA - TEESTA QUANTITIES

Cutoff walls 8500m2

Jet grouted columns n° 420u

Grouted holes n° 360u

Drilling 18 000lm

Jet grouted columns 9 300lm

Jet grout volume 14 500m3

Bentonite cement grout 1 100m3

Silicate Gel grout 900m3

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