Part 2B - Concrete Diversion Structures

8/12/2019 Part 2B - Concrete Diversion Structures

1/70

PART 2B CONCRETE DIVERSION

STRUCTURES

TABLE OF CONTENTS

1. PURPOSE OF GUIDELINES................................................................2B-1

2. SCOPE OF GUIDELINES.....................................................................2B-1

3. TERMINOLOGY..................................................................................2B-2

4. DESIGN OBJECTIVES.........................................................................2B-3

5. SCOPE OF DESIGN.............................................................................2B-4

6. DESIGN PHILOSOPHY.......................................................................2B-4

7. TYPICAL ELEMENTS..........................................................................2B-4

. GENERAL ARRANGEMENT................................................................2B-5

!. DESIGN DATA.....................................................................................2B-5

9.1 Topographical Data................................................................................2B-5

9.2 Foundation Properties...........................................................................2B-69.3 Hydrology !eteorological and "edi#entology....................................2B-69.$ "eis#ological Para#eters.....................................................................2B-69.5 %n&iron#ent...........................................................................................2B-69.6 "tructural !aterials..............................................................................2B-'

1". NON-OVERFLO# SECTION..............................................................2B-

1(.1 )ength o* +on-o&er,o "ection............................................................2B-1(.2 Pro/le.....................................................................................................2B-

11. OVERFLO# SECTION.....................................................................2B-11

11.1 Pro/le...................................................................................................2B-11

11.2 Hydraulic Design.................................................................................2B-1211.3 "tructural Design o* 0rest..................................................................2B-25

12. UNDERSLUICE................................................................................2B-26

12.1 Hydraulic Design.................................................................................2B-2612.2 "tructural Design................................................................................2B-2'

13. CONSIDERATIONS FOR PERMEABLE FOUNDATIONS..................2B-27

13.1 !easures *or "cour and "eepage 0ontrol..........................................2B-2'13.2 Hydraulic Design.................................................................................2B-213.3 "tructural Design................................................................................2B-29

14. STABILITY ANALYSIS.....................................................................2B-3"1$.1 "taility euire#ents........................................................................2B-3(1$.2 Design )oads........................................................................................2B-3(

S H A H C ON S U LT IN TE R N ATIO N A L (P.) LTD . 2 B


2/70

P AR T 2B C O NC R E T E D IV E R S ION S T R U CT U R E S

1$.3 )oading 0onditions..............................................................................2B-$11$.$ "taility 0alculations...........................................................................2B-$31$.5 "taility 0riteria..................................................................................2B-$$

15. STRESS ANALYSIS..........................................................................2B-44

15.1 "tatic 4nalysis......................................................................................2B-$$15.2 Dyna#ic 4nalysis.................................................................................2B-$6

16. PIERS..............................................................................................2B-47

16.1 Proportioning.......................................................................................2B-$'16.2 "tructural Design................................................................................2B-$

17. DIVIDE #ALLS................................................................................2B-4!

1'.1 Proportioning.......................................................................................2B-5(1'.2 "tructural Design................................................................................2B-5(

1. CONTRACTION JOINTS..................................................................2B-51

1.1 4rrange#ent o* oints.........................................................................2B-511.2 )ocation and "pacing..........................................................................2B-511.3 "hear eys...........................................................................................2B-511.$ 7aterstops...........................................................................................2B-521.5 For#ed Drains.....................................................................................2B-52

1!. GALLERIES AND OTHER OPENINGS.............................................2B-53

19.1 Types o* 8alleries and penings.........................................................2B-5319.2 8allery Details.....................................................................................2B-5$19.3 "tructural Design................................................................................2B-5$

2". BRIDGES ACROSS OVERFLO# SECTIONS....................................2B-55

2(.1 Design 0riteria.....................................................................................2B-552(.2 !aterials..............................................................................................2B-55

S HA H C ON S U LT IN TE RN ATIO N A L (P.) LTD . 2 B


3/70

D E S I G N G U I D E L I N E S F O R H E A D W O R K S O F H Y D R O P O W E R P R O J E C T S

2B

Concrete Diversion Structures

1. PURPOSE

Part 2B o* the Design Guidelines for Headworks of Hydropower

Projectspro&ides technical criteria and guidance *or the design o*concrete di&ersion structures *or heador:s o* run-o*-ri&erhydropoer pro;ects in +epal. The guidelines are intended to ensuresa*e and econo#ical design o* these structures ith dueconsideration o* rele&ant issues particularly those arising *ro#conditions typical to +epal.

2. SCOPE

The guidelines co&er the design o* concrete di&ersion structuresdee#ed suitale *or run-o*-ri&er hydropoer pro;ects in +epal. Thesestructures include eirs arrages and di&ersion structures ith non-

o&er,o and gated o&er,o sections.

The guidelines deal ith con&entional concrete gra&ity di&ersionstructures only. This class o* di&ersion structures has een *ocused onpri#arily ecause its per*or#ance under typical +epali conditions isell estalished and understood through its e


4/70


construction ti#e o>ered y their technology is not li:ely tosigni/cantly in,uence the o&erall construction period o* run-o*-ri&erhydropoer de&elop#ents en&isaged in +epal. "e#i-per#anent orte#porary type o* di&ersion structures hich are also planned inso#e pro;ects are not included in the guidelines as they are site

speci/c in nature? hoe&er the general principles discussed in theguidelines #ay e *olloed *or design o* such structures.

The guidelines presented in this part co&er the hydraulic andstructural design o* the non-o&er,o and o&er,o sections o*concrete gra&ity di&ersion structures on per#eale and i#per#eale*oundations. They discuss design considerations and data selection o*design para#eters deter#ination o* layout and pro/les hydraulicdesign load conditions staility reuire#ents stress analysis andstructural design o* these sections. Design procedures *or otherele#ents related to these sections such as aprons energy

dissipators /sh passage etc. are presented in other parts o* theguidelines.

3. TERMINOLOGY

Ter#s used in these guidelines are de/ned elo@

4Au< Di>erence in ater le&el at any point upstrea# o*di&ersion structure e*ore and a*ter its construction.

4pron Hori=ontal i#per&ious sur*ace pro&ided on upstrea#andor donstrea# side o* di&ersion structure toreduce upli*t and seepage.

Bloc:-out Te#porary recess pro&ided in structure to *acilitateproper e#ed#ent o* steel /ects o* all i#posed *orces.

0ontraction;oint

For#ed sur*ace usually &ertical in a eir or arrageto create a plane *or the regulation o* &olu#etric

changes0rest Top o* o&er,o section o&er hich ater ,os

donstrea#.0uto> C#per&ious construction placed eneath a ri&er

di&ersion structure to protect the structure againstscour and possile piping due to e


5/70

P AR T 2B C O NC R E T E D IV E R S ION S T R U CT U RE S

seepage ater co#es out *ro# susoil.Fetch "traight line distance along the ind direction along

central radial o* *etchE o&er open ater on hich theind los.

Filter 8raded #aterials used *or design o* hydraulic

structures.Freeoard ertical distance eteen a speci/ed still ater pool

sur*ace ele&ation and the top o* the di&ersionstructure ithout ca#er.

Full supplyle&el

)e&el o* ater i##ediately upstrea# o* the eir orarrage reuired to *acilitate ithdraal o* design,o discharge into the poer inta:e.

8allery )ong narro passage inside a ri&er di&ersionstructure used *or access inspection grouting ordrilling o* drain holes.

8lacis "loping portion o* the da# upstrea# and donstrea#o* the crest o* the ri&er di&ersion structure.

Ha=ard "ituation hich creates the potential *or ad&erseconseuences such as loss o* li*e property da#ageetc.

Ha=ardpotential

Potential *or loss o* hu#an li*e or property da#age inthe area donstrea# o* the di&ersion structure in thee&ent o* its *ailure or incorrect operation.

Heel o*structure

)ocation here the upstrea# *ace o* the di&ersionstructure intersects the *oundation.

Cn,o design

,ood

Flood ,o ao&e hich the incre#ental increase in

ater sur*ace ele&ation due to *ailure o* a di&ersionstructure is no longer considered to present anunacceptale threat to donstrea# li*e or property.

!ini#u#*reeoard

Di>erence in ele&ation eteen the top o* thedi&ersion structure and the #aerence in ele&ation eteen the top o* thedi&ersion structure and the nor#al #a


6/70


ele&ation eir or arrage.Toe o*structure

)ocation here the donstrea# *ace o* the di&ersionstructure intersects the *oundation.

Trans&erse;oint

4 ;oint nor#al to the longitudinal aicient and structurally adeuate arrange#ent thatsatis/es the *olloing *unctional reuire#ents in a sa*e andecono#ical #anner@

a. 7ithdraal o* desired uantity o* ater *or poer generation ithor ithout pondage.

. Passage o* surplus ,os to the donstrea# ri&er channel.

c. "a*e passage o* ,ood ,os to the donstrea# ri&er channel.

d. Passage o* trash ,oating deris and ice.

e. Passage o* sedi#ents including large oulders.

5. SCOPE OF DESIGN

The o;ecti&es listed in "ection $shall e attained through properhydraulic and structural design o* di>erent co#ponents o* thedi&ersion structure. 8enerally the design shall entail@

a. 8eneral arrange#ent o* the di&ersion structure.

. Deter#ination o* suitale pro/les and sections.

c. Hydraulic design o* co#ponents.

d. "tructural design o* co#ponents.

These acti&ities shall e per*or#ed in accordance ith the designprinciples and procedures discussed in the *olloing sections.

6. DESIGN PHILOSOPHY

0oncrete di&ersion structures *or run-o*-ri&er hydropoer pro;ectsshall e designed as solid concrete structures capale o*@

a. Pro&iding a tight and i#per&ious arrier *or di&erting andorretaining ater *or poer generation.

. !aintaining staility against design loads through their geo#etricshape and the #ass and strength o* the concrete.

c. Pro&iding adeuate ateray *or sa*ely passing ,ood ,os topre&ent o&ertopping and possile *ailure o* the di&ersion structure.

S HA H C ON S U LT IN TE RN ATIO N A L (P.) LTD . 2B - 4


7/70


d. Pro&iding adeuate head and ateray to ,ush trash deris andsedi#ent loads ithout causing signi/cant structural da#age ordistress to the aterays.

. TYPICAL ELEMENTS

4 concrete di&ersion structure *or run-o*-ri&er hydropoer pro;ectsshall typically consist o* the *olloing co#ponents@

a. 4 non-o&er,o section *or di&erting andor retaining ater.

. 4n o&er,o section *or passing eerent o&er,o ays o* thedi&ersion structure.

&i. Piers *or supporting ridges and di>erent #echanis#s *or gateoperation.

&ii. 0rest gates *or controlling ,os past the di&ersionstructure.

&iii. Bridge *or access to pedestrian and &ehicular tra>iceteen non-o&er,o sections and *or access or support *or theoperating #achinery *or crest gates.

c. 4n undersluice *or ,ushing ed loads past the ri&er inta:e.

d. 8alleries sha*ts and other openings *or *oundation groutingdrainage inspection gate operation etc.

e. Gpstrea# andor donstrea# aprons to reduce upli*t underdi&ersion structures on per#eale *oundations.

*. 0uto>s and /lters to reduce upli*t under di&ersion structures onper#eale *oundations.

g. Fish ladders /sh ypass syste#s etc. to *acilitate /sh #o&e#entpast the di&ersion structure.

h. 8uide an:s.

!. GENERAL ARRANGEMENT

0oncrete di&ersion structures shall generally e constructed on astraight a


8/70


The non-o&er,o and o&er,o sections shall *or# integral parts o*the concrete di&ersion structure. For a particular site the relati&elengths o* these sections shall depend on the total ri&er ateray andthe length o* o&er,o section needed to pass the design ,oods sa*elypast the di&ersion structure. The lengths shall e decided ased on

pro&isions o* "ections 1(.1 and 11.2.2. Cn the li#iting case thedi&ersion structure #ay consist o* an o&er,o section only.

The o&er,o section #ay e gated or ungated. 8ated o&er,osections shall e di&ided into a nu#er o* ays ith the help o* piers.The idth o* the ays shall pri#arily depend on the #a


9/70


d. )ongitudinal pro/le and cross-sections o* the ri&er at upstrea# o*and donstrea# o* the di&ersion structure site.

These data shall e otained through the topographic sur&eyprocedures discussed in Part 14 o* the guidelines.

".2 F#-/',)# P$0&,)0

Data on the *oundation properties shall e su>icient to conductstaility stress settle#ent and seepage analyses reuired *or thedesign o* the di&ersion structure. For each lithologic unit present atthe site the *olloing inde< and engineering properties shall eneeded@

a. Cnde< properties such as unit eight density and coe>icient o*per#eaility.

. De*or#ation #odulus.

c. "tatic strength properties such as alloale earing pressure andshear strength including the shear strength along the roc:-structure inter*ace.

d. Dyna#ic strength properties including elastic #odulus andPoissons ratio.

These properties shall e deri&ed *ro# the laoratory and /eldprocedures discussed in Part 1B o* the guidelines. The de*or#ation#odulus thus otained shall account *or the e>ect o* roc:inho#ogeneity due partially to roc: discontinuities on the *oundationeha&ior. 0are shall e e


10/70


are applicale to the site. They shall e otained *ro# site#easure#ents.

".4 S0)#+#%)*'+ P'&'0,0&

"eis#ological para#eters shall e reuired *or staility and stress

analysis o* the di&ersion structure. The principal para#eters needed*or these analyses include the *olloing@

a. 0ontrolling #a


11/70


deter#ined *ro# the standard uncon/ned co#pression test eects. )i:eise the tensile strength shall e deter#ined *ro#the #odulus o* rupture test or the splitting tension test earing in#ind that the *or#er pro&ides results consistent ith the assu#edlinear elastic eha&ior used in design. The shear strength along

construction ;oints or at the inter*ace ith the roc: *oundation #aye esti#ated y the linear relationship

E$. 1 tan+=c

here is the shear stress in !Pa c is the cohesion in !Pa is the

nor#al stress in !Pa and is the angle o* internal *riction.

The instantaneous #odulus o* elasticity o* concrete shall edeter#ined *ro# stress-strain cur&es otained *ro# uncon/nedco#pression tests hile its Poissons ratio shall e *ound *ro##easure#ent o* a


12/70


. 4ngle o* internal *riction.

c. 0ohesion.

These properties shall to e deter#ined ased on laoratory tests and/eld in&estigations discussed in Part 1B o* the guidelines.

1. NON7OVERFLOW SECTION

The design o* the non-o&er,o section shall consist o* deter#ining itslength and pro/le including its top ele&ation and upstrea# anddonstrea# slopes.

1.1 L0%,( #8 N#7#0&8+#9 S0*,)#

The length o* the non-o&er,o section Lno shall e deter#ined y

sutracting the reuired length o* the o&er,o sectionLo *ro# thetotal ateray o* the ri&erB i.e.

E$. 2 ono LBL =

For this purpose Loshall e co#puted in accordance ith "ection11.2.2. Cn deep and con/ned ri&ers ith stale an:s B shallapproicient depending upon the hydro-geo#orphological

characteristics o* the ri&er channel and ranging eteen $.' to $.9*or collu&ial channels eteen $.1 to $.' *or channels ith oulder-gra&el #i


13/70


transitioning into a &ertical *ace near the crest. Cn order to #eetstaility reuire#ents the donstrea# slope shall usually e in therange o* (.'H J (.H to 1 ith ,atter slopes eing selected *orhigher upli*t and seis#ic *orces.

The crest o* the non-o&er,o section shall ha&e su>icient thic:ness toresist the i#pact o* ,oating o;ects and ice loads i* any. Ct shall also*ul/ll reuire#ents *or roaday and access to gate-operating#echanis#. Cn any case the top idth o* the crest shall not e lessthan 1.5 #.

The crest ele&ation shall acco##odate the #ost critical co#inationo* ater sur*ace and *reeoard co#ponents deter#ined inaccordance ith guidelines pro&ided in "ection 1(.2.2. 4ccordinglythe crest shall e estalished at the higher o* the ele&ationsdeter#ined *ro# the *olloing co#inations o* ater sur*ace and*reeoard@

a. +or#al ater le&el ith nor#al *reeoard.

. !a


14/70


section can ithstand the P!F hile o&ertopped ithout signi/canterosion o* *oundation or aut#ent #aterial no *reeoard #ay ereuired *or the P!F condition.

10.2.2.1 Freeboar Components

The total *reeoard shall include only those co#ponents o* *reeoardthat ha&e a reasonale proaility o* si#ultaneous occurrence *or aparticular ater le&el. 8enerally the *olloing *reeoard co#ponentsshall e considered@

a. 7ind-generated a&e height and setup.

. 7a&es due to earthua:es.

c. ise o* ater le&el caused y #al*unction o* gates.

d. )andslide-generated a&es andor displace#ent o* pondage&olu#e.

10.2.2.2 Comp!tation of Freeboar

The #ini#u# *reeoard Hfm shall e deter#ined *ro# the relationapanese +ational 0o##ittee on Da#s 19'6E

E$. 4 ( ) laeswfm hhhwhH +++ 5.(#aerent return period

shall e selected ased on procedures descried in Part 1B o* theguidelines.

11.2.1.2 Permissible Specific isc%arge

The #agnitude o* per#issile speci/c discharge o&er the crest o* theo&er,o section shall e /erent *oundation conditions shall e selected *ro# the rangeslisted in Tale 3.

T9/) 3* P)(:%%9/) ,)% 8%(&) )( ,%//+ ()

Type o* *oundation Per#issile speci/c discharge#2sE

+on-cohesi&e and cohesi&e soils 3( J 5("e#i-roc:y *oundation #ergelargelite etcE

5( J 9(

oc:y *oundation gneiss schistuart=ite etc.E

9( J 12(

"ource@ +CC8 19'6E

11.2.1.3 ,imiting elocityTo a&oid ca&itation and erosion da#age to the glacis o* the o&er,osection ,o &elocities on the o&er,o section in e


19/70


openings shall e /


20/70


11.2.& Crest of #erflo Section

The crest o* the o&er,o section #ay e uncontrolled or gatecontrolled. The pro/les and discharging capacities o* to types o*crests shall e deter#ined ased on the guidelines in the *olloingsections.

11.2.&.1 5ncontrolle gee Crests

The portion o* the crest upstrea# *ro# the crest ape< shall e de/nedas a single cur&e and a tangent or as a co#pound circular cur&e%rror@ e*erence source not *oundE. )i:eise its donstrea#portion shall e de/ned y the euation G"B 19'E

E$. 13

n

oo H

!

H

y

=

hereHois the design head on the crest during design ,ood! is a

constant hose &alue depends on the &elocity o* approach otained*ro# %rror@ e*erence source not *ound and n is a constant hose&alue depends on the upstrea# inclination and on the &elocity o*approach otained *ro# %rror@ e*erence source not *ound.

Discharge "apacity

The ogee shall e proportioned to discharge the in,o design ,ood.The discharge capacity o* the ogee crest shall e deter#ined usingthe *or#ula G"B 19'E

ho Ho

ect Figure 9E and k$ is the

correction *or head other than the design head Figure 1(E.

S H A H C ON S U LT IN TE R N ATIO N A L (P.) LTD . 2B - 1 9


22/70


(

2.2(

2.1(

2.((

1.9(

1.(

1.'(

P

H(

0o

Ho

P

ht

(.5 1.( 1.5 2.( 2.5 3.(

F%&'() 6* D%(&) )%%)0 ( )8 )$'/ 8)%&0 )8@USBR 1!7

HoHa

ht

P

( (.2 (.$ (.6 (. 1.( 1.2 1.$ 1.6(.

(.9

1.(

1.1

H(

Ha

0(0

:1M

F%&'() 7* C(()%0 ( )8 )( 0 8)%&0 )8 @USBR 1!7

S HA H C ON S U LT IN TE RN ATIO N A L (P.) LTD . 2B - 2 0


23/70


3@1 1R26K3@2 33R$1K3@3 $5R((K

"lopeht

Ho

P

3@3

3@2

3@1

1.($

1.(2

1.((

(.9( (.5 1.( 1.5

P

H(

0Fertical

0"loping

:2M

"lope o* upstrea# *ace

F%&'() * C)%%)0 8%(&) /,%0& ',(): ) @USBR1!7

hdHa

Ha

P

ht hd

1.(

(.

(.6

(.$

(.2

(( (.1 (.2 (.3 (.$ (.5 (.6 (.' (.

0(Freeo&er,o-

0"u1#erged

:3M

d

F%&'() !* C(()%0 ( %/)( )) @USBR 1!7



24/70


1.(

ht

Ha

P

hd

d

1.((

(.9(

(.(

(.'61.1 1.2 1.$ 1.5 1.6 1.' 1.1.3

Ha

hdQd

0(Freeo&er,o-

0"u1#erged

:$M

F%&'() 1"* C(()%0 8') 80(): ,(0 )) @USBR 1!7

#$ecti%e Length of "rest

The &alue o* e>ecti&e lengthL used in %. 1$shall ta:e into accountthe side contractions o* the o&er,o due to crest piers andaut#ents. 4ccordingly L shall e calculated using the relationG"B 19'E

E$. 16 eapo H!&!LL += 2

hereLois the net length o* the eir crest in # otained *ro# %. '

&is the nu#er o* piers!pis the pier contraction coe>icient!a is

the aut#ent contraction coe>icient andHeis the total head on thecrest including &elocity o* approach head in #.

0oe>icient !p shall e otained *ro# Tale $. )i:eise !ashall eta:en *ro# Tale 5in hich ris the radius o* the aut#ent.

T9/) 4* P%)( 0(%0 )%%)0

Pier shape !p"uare-nosed pier ith cornersrounded on a radius eual toaout (.1 o* the pier thic:ness

(.(2

ound-nosed pier (.(1Pointed-nose pier (

"ource@ G"B 19'E

T9/) 5* A9':)0 0(%0 )%%)0

4ut#ent shape !a"uare aut#ents ith headall at 9(Sto the direction o* ,o

(.(2

ounded aut#ents ith headall at

9(S to the direction o* ,o hen (.5Ho r (.15Ho

(.(1

ounded aut#ents here r U(.5Ho (



25/70


and headall is placed not #ore than$5S to the direction o* ,o

"ource@ G"B 19'E

'odel (est

Hydraulic #odel tests on ungated ogee crest shall e per*or#ed i* thedirection o* ri&er ,o is not at perpendicular to the crest. The tests#ay also e desirale i* other site conditions #a:e relialecalculation *or design o* the o&er,o section di>icult.

11.2.&.2 *atecontrolle gee Crest

4 gate-controlled ogee crest #ay e designed to *ollo the idealnappe pro/le *or #aecti&e length o* the eir crest in # g is the

acceleration due to gra&ity in #s2 H1 is the total head including

&elocity head o* approachE to the otto# o* the ori/ce in #H2is thetotal head including &elocity head o* approachE to the top o* theori/ce in # and " is the discharge coe>icient otained *ro# Figure11.



26/70


ht

H2H1

1.9(

1.95

2.((

2.(5

2.1(

2.15

( (.1 (.2 (.3 (.$ (.5 (.6 (.'

H1

H1-H2elati&egate opening

Discharge0o>icient0

F%&'() 11* D%(&) )%%)0 ( '08)( &) @USBR 1!7

%. 1shall e used *or co#puting the discharge capacity o* a gatedcrest till the gate opening is less than to-third o* the upstrea# aterdepth. 4s a transition to *ree sur*ace ,o occurs *or larger openings%. 1$shall e used *or co#putation o* discharge capacity.

'odel (est

!odel tests shall e per*or#ed *or an accurate deter#ination o* thedischarge capacity o* a gated ogee crest. These tests shall study thee>ects o* the shape and length o* the side alls the radius andinclination o* the gates and the location o* the gate in relation to thecrest.

11.2.) *lacis an Flo 7ransition

The slope and length o* the glacis shall e deter#ined y the *or#and di#ensions o* the structure and y the sche#e *or transition o*,o *ro# the glacis to the donstrea# energy dissipation. For thesur*ace ,o transition the cur&ilinear transition part shall eter#inated ith the nose-tra#plline the le&el o* hich shall e /


27/70


11.2.).1 Flo Parameters for *lacis

The depths and &elocities o* the gradually &aried ,o o&er glacis shalle deter#ined either y co#puter progra#s or y draing the atersur*ace pro/le considering energy losses and ,o aeration. 4erationshall e ta:en into account *ro# a section at hich the #ean ,o

&elocity eicient o* roughness.

Cn asence o* aeration the ater sur*ace pro/le eteen tosections iand iQ1 shall e dran using the *olloing set o* euations+CC8 19'6a E@

E$. 21 ( ) li+g

%h

g

%h f

idi

idi =+

++

2cos

2cos

221

1

E$. 22 11 ++= iiii %h%h

here hiis the depth o* ,o at section i,, %iis the &elocity o* ,o atsection i, g is the acceleration due to gra&ity +is the slope o* the

spillay glacis lis the distance eteen sections iand iQ1 and ifisthe #ean &alue o* the *riction angle o* ,o in the length consideredgi&en y +CC8 19'6a E.

E$. 23mm

mf

*"

%i

2

2

=

here %mis the #ean &elocity o* ,o eteen sections iand iQ1*mis the #ean hydraulic radius o* the ,o section eteen sections i

and iQ1 and "mis the #ean 0he=ys coe>icient co#puted using therelation +CC8 19'6aE

E$. 24611

mm *"

" =

Cn the initial part o* the glacis up to 5 to 1( ti#es H,here headlosses can e neglected the depth and &elocity o* ,o shall edeter#ined *ro# the *olloing euations +CC8 19'6a E

E$. 25 )Hg

%h od +=+

2cos

2

E$. 26 %q=

here ) is the di>erence in ele&ation eteen the crest o* theo&er,o section and the section o* the glacis under consideration.

The pie=oelectric pressure p on the glacis shall e deter#ined *ro#

the *or#ula +CC8 19'6a E



28/70


E$. 27 diwhp cos=

here wis the unit eight o* ater.

0alculation o* the contraction and e


29/70


E$. 32 ( )11 2 h(g% o=

here (o is the speci/c energy o* ,o ehind the structure ithrespect to the sur*ace o* the stilling asin andor tailater sur*ace

le&el and is a &elocity coe>icient &arying *ro# (.9 to (.95.

11.2.6 Ca#itation

The pheno#ena o* ca&itation and ca&itation erosion shall econsidered in the design o* o&er,o sections hich e


30/70


!PaE"ource@ +CC8 19'6E

T9/) 7* V/') ,()'() ,'( (:%0

7ater te#perature S0 1( 15 2( 25 3(

Pressure o* &apor *or#ationp%!PaE(.(13 (.(1' (.(2$ (.(33 (.($5

"ource@ +CC8 19'6E

4lternati&ely ca&itation #ay e assu#ed to occur hen +CC819'6E

E$. 34 ci !!

here !cr is the critical ca&itation para#eter de/ned *or so#e

ele#ents in Tale and!i is a ca&itation para#eter characteri=inghydrodyna#ic condition o* ,o in relation eteen the pressure and

,o &elocity at the considered point de/ned as

E$. 35 22 5.(5.( ch

%ch

i

%ii

%

pp

%

pp!

=

=

here pch is the characteristic pressure adopted as the design

#agnitude *or gi&en point o* ,o %ch is the characteristic ,o&elocity adopted as the design #agnitude &alue *or gi&en point o* ,o

andis the ,o density.

T9/) * T+,%/ /') Kcr

Types o* irregularity ":etch o* irregularity !crHu#p to ,o

=d

%

For 9(53

466.0

e&erse hu#p to,o

=d

%

For 9(U2(

1 for =d

( ) 43dz *or =dN

eing thethic:ness o* theoundary layer

Gni*or# naturalroughness o* sur*aceith a&erage height

o* hu#ps

=dM(

%

1.(

"ingle hu#p ithsharp upper edgethroughout section

=d

%

2.(



31/70


"eparated e


32/70


eerence in radii o* diaphrag#sE and %mis the #ean &elocity o* ,oo* ater.

Cn other cases Qairshall e deter#ined e


33/70


egion near pierB7

egion aay *ro# pier

egion aay *ro# pier

00

a

B7-B2

$5R

1

2

1

2

B7-B2

0rest %)

B

0rest %)

adial gateTypical crestrein*orce#ent

Foundationgalley

Pier

Da# aect o* the sheet o* ater ,oing o&er the crest

*or upli*t calculations #ay e ignored. For tailater le&els ao&e thesection considered upli*t at the donstrea# end and the eight o*ater ao&e crest shall e suitaly considered.

11.3.3 +inim!m Concrete 7%ickness

The #ini#u# thic:ness o* structural concrete at the crest shall e l.5# #easured nor#ally. This thic:ness has to e suitaly increased toacco##odate the anchorage elo the piers.

11.3.& Reinforcement

0rest rein*orce#ent shall e pro&ided only in regions here the

co#puted tensile stresses e


34/70


35/70


12.2 S,&-*,-&'+ D0)%

"tructural design o* the undersluice shall e per*or#ed in accordanceith the pro&isions *or the o&er,o section. Cn so#e cases theundersluice #ay e designed as a rein*orced ce#ent concrete ra*t.

For protection against arasion *ro# rolling oulders the sur*ace o*the undersluice shall e lined ith arasion resistant #aterial re*er"ection 11.2.'E. "i#ilarly the &ertical *aces o* di&ide alls and otherstructures autting against the undersluice sur*ace shall e pro&idedith arasion-resistant #aterial up to a #ini#u# height o* 1 # ao&ethe undersluice sur*ace.

13. CONSIDERATIONS FOR PERMEABLE FOUNDATIONS

Di&ersion structures constructed on per&ious *oundations oulder-gra&el #i


36/70


13.1.1 prons

4 concrete apron #ay e placed upstrea# o* the di&ersion structurein con;unction ith one o* the &arious types o* cuto> alls to increasethe length o* the path o* seepage therey reducing upli*t under the#ain portion o* the di&ersion structure. The apron shall usually e

connected to the di&ersion structure and to a concrete cap o&er thepiling ith ,eerential #o&e#ent tota:e place ithout acco#panying detri#ental crac:ing. The sa*ety o*the structure #ay e *urther i#pro&ed y placing an i#per&ious earthlan:et o&er a portion o* the concrete apron and the strea#edupstrea# *ro# it.

Donstrea# concrete aprons #ay e pro&ided to lengthen the path o*seepage in the *oundations and also create a asin here the surplusenergy o* the o&er,oing ater #ay e sa*ely dissipated. Cn caseshere it is not *easile to construct a concrete apron o* su>icient

length to a&oid erosion entirely additional protection #ay e gainedy placing riprap donstrea# *ro# the apron.

13.1.2 C!toff "alls

0uto> alls #ay e constructed o* concrete ce#ent-ound curtainssteel sheet piling or i#per&ious earth co#pacted in a trench. The typeo* cuto> shall depend upon the type o* the *oundation #aterial andthe depth o* the cuto>s.

0oncrete cuto>s #ay e used under aprons or under the di&ersionstructure at sites here under-seepage is large. Ct #ay also e usedunder the di&ersion structure to increase the sliding resistance o* thestructure.

"heet piling cuto>s o* interloc:ing steel sections #ay e used underthe aprons o* di&ersion structures. They shall e anchored to theapron or di&ersion structure y #eans o* concrete caps.

13.1.3 Filters an rains

elie* o* upli*t pressures under the apron or donstrea# toe o* thedi&ersion structure #ay e acco#plished y drains. Drains shallgenerally e o* seer pipe laid in graded #aterial hich acts as a/lter. They #ay e per*orated pipe or plain pipe laid ith open ;oints.

The drains #ay e located at the donstrea# toe o* the di&ersionstructure at selected places under the donstrea# apron andi##ediately upstrea# *ro# the donstrea# cuto>.

7eep holes shall nor#ally e used *or relie* o* upli*t pressure underaprons and ehind alls. To pre&ent piping the gradation o* the /lter#aterials used in con;unction ith the eep holes shall e care*ullyselected ith respect to the gradation o* the *oundation #aterials.Both uni*or# grain-si=e and graded /lters #ay e used.

13.2 H/&'-+)* D0)%

Hydraulic design o* the aprons and cuto>s shall e ai#ed atproportioning these ele#ents to control the a#ount o* seepage under



37/70


the di&ersion structure and to li#it the intensity o* the upli*t so thatthe staility o* the structure is not threatened.

13.2.1 Comp!tation of 5plift Press!re

The upli*t pressure at any point under the di&ersion structure shall e

calculated y any accepted practice. The calculation shall ta:e intoaccount se&eral *actors such as the head on the di&ersion structuredepth o* the per#eale strata elo the structure per#eaility o* the*oundation #aterial length o* upstrea# and donstrea# apronsdepths and tightness o* cuto>s and e>ecti&eness o* the drains. Cngeneral the upli*t pressure at any point under the di&ersion structure#ay e co#puted using )anes eighted creep #ethod the ,o net#ethod hoslas theory o* independent &ariales or the /niteele#ent #ethod.

13.2.2 pron

The total lengths o* the upstrea# and donstrea# aprons shall e/ to satis*y thereuire#ents o* es shall generally e pro&ided tocater *or scours up to 1 to 1.25 ti#es the depth o* scour respecti&ely.For *oundation #aterial the depth o* scour #ay e calculated as perthe pro&isions *or donstrea# protecti&e apron in Part 0 o* theseguidelines.

13.2.& Filters an rainsFilters and drains shall e designed in accordance ith the pro&isionsdescried in Part 0 o* these guidelines.

13.2.) 5pstream Protection "orks

The ri&er stretch upstrea# o* concrete di&ersion structures uilt onper&ious *oundations shall e protected against scour. The length o*upstrea# protection shall appros shall essentially consist o*proportioning the# and to enale the# to sa*ely resist all *orces



38/70


acting on the#. Cn rein*orced concrete ele#ents co#putation o*rein*orce#ent shall also e per*or#ed.

13.3.1 C!toffs

13.3.1.1 esign ,oa Conitions0uto>s shall e designed to resist the orst co#ination o* *orcesand #o#ents acting on the#. The principal consideration inco#puting these *orces and #o#ents shall include the *olloing@

a. Possile scour on the outer side.

. %arth pressure and surcharge due to ,oor loads on the inner side.

c. Di>erential hydrodyna#ic pressure co#puted on the asis o* thepercentage o* pressure o* seepage ,o elo the ,oor.

13.3.1.2 Steel S%eet Piles

The steel sheet pile cuto> shall e designed as sheet pile retainingalls anchored at its top. C* its e>ect in resisting the *orard slidingo* the structure is ta:en into account the cuto> shall also edesigned to ithstand the passi&e pressures thus de&eloped. Therein*orced concrete pile caps shall e designed to trans#it the *orcesand #o#ents acting on the steel sheet pile cut-o>s to the aprons orthe di&ersion structure.

13.3.1.3 Reinforce Concrete "alls

ein*orced concrete cuto>s shall e designed to resist *orces and#o#ents as a cantile&er all cast #onolithically ith the apron ,oor

or the di&ersion structure. The hori=ontal load on the cantile&er shalle ta:en as the load that is in eerent conditions includingseis#ic conditions. The thic:ness adopted *or construction shall e atleast 1( percent greater than the thic:ness reuired to counteract theupli*t pressure

14. STABILITY ANALYSIS

"taility analysis o* the non-o&er,o and o&er,o sections o*concrete di&ersion structures shall e conducted to chec: their#argin o* sa*ety against o&erturning sliding ,otation ando&erstressing.



39/70


14.1 S,':)+), R0;-)&00,

For all load conditions they are li:ely to e su;ect to during theirli*eti#e the non-o&er,o and o&er,o sections shall satis*y the*olloing staility reuire#ents@

a. The section shall e sa*e against o&erturning at any hori=ontalplane ithin it at its ase or at a plane elo its ase.

. The section shall e sa*e against sliding on any hori=ontal or near-hori=ontal plane ithin it at its *oundation or ithin the*oundation.

c. The alloale unit stresses in the concrete or in the *oundation#aterial shall not e e


40/70


For preli#inary designs the unit eights o* di>erent construction#aterials used in the dead load calculations shall e ased onstandard &alues. Hoe&er *or /nal designs dead load calculationsshall e ased on actual data *ro# laoratory tests. "i#ilarly theeights o* gates and appurtenances shall e otained *ro# their

#anu*acturers.

1&.2.2 $eaater an 7ailater Press!res

The hydrostatic pressures due to head and tailater shall edeter#ined *ro# the hydrology #eteorology and pool regulationstudies. The pool le&els corresponding to di>erent load conditionsshall e selected ased on an assess#ent o* their *reuency.

1&.2.2.1 ono#erflo Section

Hydrostatic pressure on the upstrea# and donstrea# *aces o* thenon-o&er,o section shall e assu#ed to &ary linearly ith depth and

act nor#al to the *ace o* the section Figure 1$E. The tailaterpressure ad;usted *or any retrogression shall e ta:en at its *ull&alue.

Hydrostatic pressures shall e co#puted assu#ing the unit eight o*ater as 1( :+#3. ariations in this &alue due to te#peraturechanges shall nor#ally e neglected.

eser&oir ater sur*ace

H

h

7

7c

7KG

P

P

7

H

e

T2

T2

G

DhK

PK PK

Tailatersur*ace

Baseo* section0entero* gra&ityo* ase

7K M 7eight o* tailater7 M 7eight o* headater7c M 7eight o* non-o&er,osectionH M Hori=ontal *orcedueto headaterHK M Hori=ontal *orcedueto tailater"7 M esultant &ertical *orceao&ease"H M esultant hori=ontal *orceao&easee M %ccentricityP M Gpli*t pressuredueto headaterPK M Gpli*t pressuredueto tailaterG M Gpli*t *orce

HK

F%&'() 14* #)( ,()'() %0& 0 00-)( )%0 @USBR1!7

1&.2.2.2 #erflo Section

Headater pressure on gated o&er,o sections shall e co#putedassu#ing the gates to e part o* the concrete section. For ungatedo&er,o sections the lateral pressure distriution due to headater



41/70


shall e assu#ed to e trape=oidal Figure 15E. The &ertical pressureo* ater ,oing o&er the crest shall e neglected in &ie o* the *actthat this pressure is greatly reduced due to the ater approachingspouting &elocity. Because o* its high &elocity the strea# o* ater onthe donstrea# *ace o* the o&er,o section shall also not e

considered in the analysis.

h

0onstruction ;oint

hK

P

!aecti&e tailater depthshall e suitaly reduced to ad;ust *or retrogression. This reductionshall depend on the degree o* su#ergence o* the crest the type o*energy dissipation arrange#ent and the anticipated donstrea#ater pro/le. For deep ,o o&er the o&er,o section the e>ecti&edepth #ay e ta:en eual to 6( percent o* the *ull tailater depth.

1&.2.3 5plift

Gpli*t pressure resulting *ro# headater and tailater shall econsidered to act ithin the ody o* the di&ersion structure along theinter*ace o* the structure and its *oundation and ithin the *oundationelo the ase.

1&.2.3.1 5plift ss!mptions

The upli*t pressure acting on any *ailure plane ithin the di&ersionstructure along its ase or elo the ase shall e co#puted asedon the *olloing assu#ptions@

a. egardless o* the o&er,o conditions the upli*t pressure at thetoe o* the di&ersion structure corresponds to the *ull tailaterdepth.

. Gpli*t pressures act o&er the entire area o* the *ailure plane underconsideration.

c. Gpli*t pressures re#ain una>ected y earthua:e loads.



42/70


1&.2.3.2 5plift it%in i#ersion Str!ct!re

Gpli*t pressures along *ailure planes ithin the ody o* the concretedi&ersion structure shall e assu#ed to &ary *ro# 1(( percent o* thenor#al headater at the upstrea# *ace to 1(( percent o* thetailater or =ero as the case #ay e at the donstrea# *ace. 7here

&ertical drainage is pro&ided ithin the di&ersion structure the draine>ecti&eness and upli*t assu#ptions shall *ollo the guidancepro&ided in "ection 1$.2.3.3.

1&.2.3.3 5plift along Base of Str!ct!re on Rock Fo!nation

The upli*t pressure along the ase o* a concrete di&ersion structure*ounded on roc: shall e esti#ated considering the *olloing@

a. Pro&ision and e>ecti&eness o* #easures such as drains andorgrout curtain andor aprons *or upli*t reduction.

. 8eologic *eatures such as roc: per#eaility sea#s ;ointing and

*aulting.

Di%ersion +tructure without 0oundation Drains

7here *oundation drains are not pro&ided upli*t at the *oundation-concrete inter*ace o* the di&ersion structure shall e assu#ed to &arylinearly *ro# the *ull headater pressure at the heel o* the structureto the *ull tailater pressure at its toe. For this case upli*t at anypoint on or elo the *oundation shall e deter#ined ased on Figure16.

H1

H2

7

H2

ecti&eness o* the drainage syste# #ay e assu#ed to&ary *ro# 25 to 5( percent. 7here the line o* drains intersects the*oundation ithin a distance o* 5 percent o* the headater depth*ro# the upstrea# *ace the upli*t #ay e assu#ed to &ary as a singlestraight line Figure 1E. C* the drainage gallery is located ao&etailater le&el the pressure at the line o* drains shall e deter#inedas though the tailater le&el is eual to the gallery ele&ation.

Headater

Tailater

Drainage galleryH1

H$ H2

)

H1H3

H2

Drains

7hen H$U H2@

H3M H1-H$E QH$

7hen H$N H2@

H3M H1-H2E QH2

7here @% M Drain e>ecti&eness e


44/70


Headater

Tailater

Drainage galleryH1

H$ H2

)

H3

H2

Drains

7hen XM (.(5H1C* H$U H2

% M Drain e>ecti&eness e


45/70


Headater

Tailater

DrainagegalleryH1

H$ H2

)

Drains

H1

T

7hen H$UH2@

H3MPYH1-H2EP QH2-H$ZQH$

7hen H$NH2@

7here@% MDrain e>ecti&eness e


46/70


/prons

eduction in upli*t pressure at the heel o* the di&ersion structure dueto an upstrea# apron shall e considered i* the ;oints in the apronand the ;oints eteen the di&ersion structure and apron shall *or#an i#per#eale arrier throughout the range o* #o&e#ent eerential settle#ent orcontraction due to te#perature changes. Cn the case o* donstrea#aprons the upli*t #ay e assu#ed to e li#ited to that hich ould,oat the apron.

0lood Loading

Gpli*t reductions shall not e ased on the assu#ption that the CDF,ood e&ent shall e o* such short duration and the *oundationper#eaility so lo that the ele&ated headater and tailaterpressures are not trans#itted under the ase o* the di&ersionstructure. For design purposes upli*t shall e assu#ed to &ary

directly ith changes in headater and tailater le&els.

1&.2.3.& 5plift along Base of Str!ct!re on Per#io!s Fo!nation

The #agnitude o* upli*t pressures acting upon the ase o* a di&ersionstructure constructed on per&ious *oundation shall e esti#ated usingthe eighted creep #ethod the ,o net #ethod or the /nite ele#ent#ethod.

1eighted "reep 'ethod

Gsing creep theory the upli*t pressure at any point shall e co#puted*ro# the su# o* the seepage potential and position potential.

0low &et 'ethod

The ,o net #ethod shall e used *or co#puting upli*t pressures i*the actual *oundation stratigraphy and oundary conditions can erepresented as ho#ogeneous and isotropic. Cn this #ethod ,o linesand euipotential lines shall e constructed *or the susur*ace ,oand the upli*t pressure shall e co#puted.

0inite #lement 'ethod

To and three-di#ensional /nite ele#ent ground ater #odeling #aye used to deter#ine the upli*t pressure in per#eale *oundations.

This #ethod #ay e adopted *or sites here #aterial anisotropy isli:ely to ha&e a signi/cant e>ect on upli*t pressures.

1&.2.3.) 5plift it%in Fo!nation

Gpli*t pressure distriution along identi/ed *oundation *ailure planesshall nor#ally assu#e a uni*or# head loss along the *ailure sur*ace.eduction in upli*t pressures along the *ailure plane #ay e assu#edi* the *oundation drains penetrate the# and are e>ecti&e.

1&.2.& appe Press!res

4t s#all discharges nappe *orces on the o&er,o section due to

steady state hydrodyna#ic e>ects #ay e neglected. Hoe&er as thedischarge o&er an o&er,o section approaches the design dischargenappe *orces ith o&erturning e>ect on the o&er,o section na#ely



47/70


su-at#ospheric crest pressures and dyna#ic uc:et pressures shalle considered in the staility analysis. Cn particular su-at#osphericcrest pressures shall e considered *or high o&er,o crests hiledyna#ic uc:et pressures shall e ta:en into account *or oth highand lo o&er,o sections.

Gsing this #ethod the depth o* ,o at the point under Figure 21Econsideration shall e co#puted y sol&ing the *olloing relationnu#erically *or the gi&en unit discharge Brand 1999E

E$. 37 ( ) ( )AAAYEgq e

= 1log1

1sin2

here qis the unit discharge#is the total energy 5is the ele&ationo* the point on the o&er,o section under consideration / is thedepth o* ,o #easured perpendicular to the sur*ace o* the o&er,o

section is the angle o* the outard directed to the o&er,o section

ith the hori=ontal is the cur&ature o* o&er,o sur*ace at pointunder consideration ta:en positi&e *or uc:ets and negati&e *or

crestsLhis the hori=ontal length o* creep path and L%is the &erticallength o* creep path.

X

I

Felocitydistriution

4"

[

Pressuredistriution

F%&'() 21* V)/%+ 08 ,()'() ))()8 9+ )( 0 )( )%0

7ith/ deter#ined the &elocity o* ,o at the o&er,o sur*ace shalle *ound *ro# the euation Brand 1999E

E$. 3 ( ) sin12 AYEAgVs =The pressure head at the o&er,o sur*ace shall then e deter#ined*ro# the euation Brand 1999E

E$. 3!g

VYEH s

s2

2

=

1&.2.) 'art%(!ake Forces

The seis#ic coe>icient or the pseudo-static #ethod shall e used *orstaility analysis o* concrete di&ersion structures under hori=ontalseis#ic acceleration. To types o* loadings shall e considered Jinertia *orce due to hori=ontal acceleration o* the di&ersion structureand hydrodyna#ic *orces resulting *ro# the reaction o* the reser&oirater against the di&ersion structure Figure 22E.



48/70


1&.2.).1 /nertia Force

The inertia *orce due to hori=ontal and &ertical acceleration o* asection or ele#ent o* the di&ersion structure shall e calculated *ro#the euations

Headater

Tailater

Pe

Pe

h

.$h

Peice *ordi&ersion structures. 7here reuired nonlinear /nite ele#entanalyses that account *or interaction o* the di&ersion structure andthe *oundation #ay also e conducted. The #ethod #ay also e used*or #odeling concrete ther#al eha&ior in con;unction ith otherloads.

1).1.2.1 7oimensional nalysis

To-di#ensional /nite ele#ent analysis shall nor#ally e adeuate*or concrete di&ersion structures. Ct shall particularly e suitale *oranaly=ing sections o* structures here plane strain or plane strains

eects #ay also e appro


58/70


The di&ersion structure is 3( # or #ore in height and the pea:ground acceleration P84E at the site is greater than (.2 g *or the!0%?

The di&ersion structure is less than 3( # high and the P84 at thesite is greater than (.$ g *or the !0%?

The di&ersion structure has gated spillay #onoliths ideroadays inta:e structures or other #onoliths o* unusual shape orgeo#etry.

1).2.1 ynamic +et%os of Stress nalysis

Dyna#ic #ethods *or stress analysis o* di&ersion structures shall eased on the #odal analysis techniue. These techniues include asi#pli/ed response spectru# #ethod and the /nite ele#ent #ethodsusing either a response spectru# or acceleration-ti#e records *or thedyna#ic input. 4 dyna#ic analysis shall egin ith the response

spectru# #ethod and progress to #ore re/ned #ethods i* needed. 4ti#e-history analysis shall e used hen yielding crac:ingE o* thedi&ersion structure is indicated y a response spectru# analysis.

1).2.1.1 Simplifie Response Spectr!m +et%o

The si#pli/ed response spectru# #ethod shall e used to co#putethe #aects shall e #odeled as an added #ass o* ater#o&ing ith the structure the a#ount o* the added ater #assdepending on the *unda#ental *reuency o* &iration and #ode shapeo* the structure and the e>ects o* interaction eteen the structureand reser&oir. "eis#ic loading shall e co#puted directly *ro# thespectral acceleration otained *ro# the design earthua:e responsespectru# and *ro# the dyna#ic properties o* the structural syste#.

1).2.1.2 Finite 'lement +et%os

Finite ele#ent #ethods *or dyna#ic stress analysis shall e used to#odel the response o* the higher #odes o* &irations o* di&ersionstructures.

'odeling /pproach

Finite ele#ent #odels *or dyna#ic analysis shall accurately #odel thestructures geo#etry and in particular shall include &oids and anylu#ped #asses hich #ight a>ect the &iration #ode shapes o* thestructure. Because &ariations in #odeling para#eters anduncertainties in #aterial properties signi/cantly a>ect stressdistriutions in the structure a nu#er o* analyses shall e

per*or#ed to test the sensiti&ity o* the dyna#ic eha&ior to &ariousco#inations o* properties and assu#ptions. The ulti#ate strengths



59/70


o* the #aterials #ay e used in earthua:e analyses using dyna#ic#ethods.

0inite #lement *esponse +pectrum 'ethod

The /nite ele#ent response spectru# #ethod shall e used to #odel

the dyna#ic response o* linear to- and three-di#ensional di&ersionstructures. Ct shall e used *or #onoliths that cannot e #odeled to-di#ensionally or i* the #a


60/70


1).2.2 Performance Criteria for Response to Siteepenent 'art%(!akes

0oncrete di&ersion structures shall e capale o* sur&i&ing thecontrolling !0% ithout a catastrophic *ailure that ould lead to losso* li*e or signi/cant da#age to property. Cnelastic eha&ior ithassociated da#age shall e per#issile under the !0%. Further#ore

they shall e capale o* resisting the controlling B% ithin theelastic range re#ain operational and not reuire e


61/70


16.1.3 $eig%t of Pier

n the upstrea# side the pier shall generally e constructed ao&ethe pond le&el aAu


62/70


#. 7ind load.

n. %arthua:e loads including hydrodyna#ic *orces.

o. )ongitudinal static ater pressure on the pier.

p. Forces due to ater current.

16.2.2 ,oa Conitions

The pier shall e designed *or the #ost critical co#ination o* loadslisted in "ection 16.2.1. "ince each pier supports a gate on each sidethe *olloing pier loading conditions Tale 11E shall e in&estigated.

0ases 1 and 3 shall e considered to calculate the #a


63/70


. To separate ays ha&ing the sa#e type o* energy dissipationarrange#ent hich ha&e di>erent le&els or para#eters ecause o*geological or other considerations.

c. To allo *or unsy##etrical operation o* crest gates in order to#ini#i=e cross or return ,os eddies etc.

1.1 P$#&,)#)%

Cn order to #ini#i=e disturance to the ,o di&ide alls shallnor#ally e pro&ided in line ith the crest piers. Their sections shalle #ade as thin as possile.

The height o* di&ide alls shall e /icient *reeoard o&er the #aected y an earthua:e.

%sti#ates o* hydro-dyna#ic pressures due to turulence and surgesshall e ased on #odel studies. Hoe&er till results o* such tests area&ailale esti#ates o* these pressures #ay e #ade ased onsi#pli/ed assu#ptions.



64/70


1-.2.2 ,oa Conitions

The di&ide all shall e designed *or the load conditions listed inTale 12.

1!. CONTRACTION JOINTS

Trans&erse contraction #onolithE ;oints shall e pro&ided in concretedi&ersion structures *or the *olloing purposes@

a. Pre&ent the *or#ation o* hapha=ard ragged crac:s resulting *ro#&olu#e changes that cannot e pre&ented in the #ass concrete.

. Di&ide the structure into con&enient si=ed #onoliths to per#itcon&enient and syste#atic construction.

T9/) 12* L8%0& 08%%0 ( 8%%8) //

0ondition )oads

Gnsy##etrical spillayoperation

Dead loads Hydrostatic and hydrodyna#ic loads due to

unsy##etric ,o in the energy dissipatorincluding centri*ugal *orces in the case o* ,ipuc:ets

0orresponding *ull upli*t"pillay notdischarging

Dead loads Hydrostatic and hydrodyna#ic loads on only

one side o* all 0orresponding *ull upli*t %arthua:e *orces

1!.1 A&&'%00, #8 J#),

The ;oints shall e &ertical and nor#al to the a


65/70


1!.3 S(0'& K0

7here *oundation conditions o* the di&ersion structure are such thatundesirale di>erential settle#ent or displace#ent #ay occur shear:eys #ay e *or#ed in the contraction ;oints Figure 23E. These ;oints#ay e *or#ed &ertically hori=ontally or as a co#ination o* oth

depending on the direction o* the e


66/70


Flo

G" *ace o* da#To gallery,oor drain

0onstruction ;ointP0 ater stop

For#ed trap drain

F%&'() 24* T+,%/ )(, %0//%0

1!.5 F#&0/ D&')

4 15( to 2(( ## dia#eter *or#ed drain shall generally e pro&idedeteen the to ater stops Figure 2$E. Cn the non-o&er,o#onolith ;oints the drains shall eiciency and

their location ith respect to #aintaining the structural integrity.



67/70


19.1.1 *ro!ting an rainage *allery

The grouting and drainage gallery shall e and *orcollecting seepage *ro# *oundation drainage holes and the interiordrainage holes. 8enerally it shall e pro&ided *or di&ersion structures

hose height ao&e the nor#al *oundation le&el eerent le&els ao&e the grouting and drainagegallery. Hoe&er the top o* the gallery at the highest le&el shall note located ithin ' # o* the crest le&el o* the o&er,o section. Thesi=e o* the gallery shall e 1.5 # ide y 2.5 # high.

19.1.& /nstr!mentation *allery

The nu#er and location o* instru#entation galleries shall dependupon the e


68/70


19.1.) S!mp "ell an P!mp C%amber

"u#p ells shall e pro&ided in the deepest location. Their nu#erand si=e shall depend upon the uantity o* ater seeping through the*oundations and the ody o* the di&ersion structure.

0ha#ers *or housing pu#ps *or pu#ping o> the ater collected inthe su#p ells shall e located ad;acent to an inspection gallery. Ct#ay also e located in an area that can e easily assessed in thee&ent o* the drainage gallery eing ,ooded.

19.1.6 S%afts

"ha*ts *or staircases and ele&ators shall e pro&ided *or access togalleries *ro# the top o* the di&ersion structure. They shall e locatedin the non-o&er,o section generally near the inter*ace o* the non-o&er,o section ith the o&er,o section.

1".2 G'++0& D0,')+

8alleries #ay e usually arranged as a series o* hori=ontal runs andstair ,ights or ra#ps ith slopes pre*eraly not eice. Hoe&er three-di#ensional analysis #ay ereuired at intersections o* to or #ore openings.

For the stress analysis the o&erall stress /eld pre&ailing at the centero* the gallery shall e deter#ined y appro


69/70


de&eloped *or rectangular openings o* &arious idth and height.Finite ele#ent analysis #ay e conducted *or openings that ha&eco#ple< *or#s and load conditions. This analysis #ay e needed *oropenings located close to the *ace o* the di&ersion structure or nearthe *ace o* a loc: *or #ultiple openings in on plane and *or

intersections.

19.3.2 ,oa Conitions

8alleries and openings shall e designed *or the o&erall stress /eldresulting *ro# the #ost ad&erse co#inations o* loads acting on thedi&ersion structure. For this purpose the load cases discussed in"ection 1$.2 and the load conditions listed in "ection 1$.3shall eused? hoe&er upli*t shall not e considered.

19.3.3 Reinforcement

ein*orce#ent shall e designed *or the total tensile *orce across the

plane considered *or design. This *orce shall e deter#ined yintegrating the tension stress on the plane. The area o* steelrein*orce#ent shall e calculated y di&iding the tensile *orce y thealloale tensile stress o* the rein*orce#ent.

ein*orce#ent pro&ided *or resisting tensile stresses shall consist o*hori=ontal and &ertical ars on the periphery and diagonal ars atcorners. These ars shall e anchored in a =one o* co#pression. Thespacing o* ars shall generally not e less than 15( ## centers andnot greater than 3(( ## centers. The #ini#u# clear co&er torein*orce#ent shall e 15( ##. The #ini#u# dia#eter o*

rein*orce#ent ars shall e 16 ## *or #ain rein*orce#ent and 12## *or distriution rein*orce#ent.

2. BRIDGES ACROSS OVERFLOW SECTIONS

Bridges shall e pro&ided across o&er,o sections to *urnish access*or pedestrian and &ehicular tra>ic eteen the non-o&er,osections to pro&ide access or support *or the operating #achinery *orthe crest gates? or usually to ser&e oth purposes. Cn the case o* anungated spillay and in the asence o* &ehicular tra>ic accesseteen the non-o&er,o sections #ay e pro&ided y a s#all accessridge or y stair sha*ts and a gallery eneath the spillay crest.

2.1 D0)% C&),0&)'

The class o* ridge design loading shall nor#ally not e less thanCndian oad 0ongress C0E 0lass 44 loading. "pecial loadingsreuired *or operation and #aintenance *unctions and those that theridge is su;ected to during construction shall e ta:en into accountincluding pro&isions *or any hea&y concentrated loads. Hea&yloadings *or consideration shall include those due to euip#enttransported during construction #oile cranes used *or #aintenanceand gantry cranes used to operate gates and to install stop logs *orthe o&er,o section. C* the structure carries a highay the designshall usually con*or# to the standard speci/cation *or highayridges in +epal.



70/70


2.2 M',0&)'+

!aterials used in the design and construction o* the ridge shall eselected on the asis o* li*e cycle costs and *unctional reuire#ents.Floors curs and parapets shall e rein*orced concrete. Bea#s andgirders #ay e structural steel precast or cast-in-place rein*orced

concrete or prestressed concrete.

Date post:	03-Jun-2018
Category:	Documents
Upload:	prabinkarki
View:	223 times
Download:	0 times

Part 2B - Concrete Diversion Structures

Documents