4. highway drainage -lecture version 073.pptx

7/25/2019 4. highway drainage -lecture version 073.pptx

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CHAPTER # 04

HIGHWAY DRAINAGE(8 @ 80 = 10%)

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Topics as pe !"a$s

4.1 Introduction and Importance of HighwayDrainage System

4.2 Causes of oisture !ariation in Su"grade Soi#

4.$ Surface Drainage System

4.$.1 Di%erent &ypes of 'oad Side Drain

4.$.2 Cross Drainage Structures (Cu#)erts and*thers+

4.$.$ Di%erent &ypes of ,nergy Dissipating

Structures

4.4 Su"-surface Drainage System

4.4.1 Drainage of In#tered ater

4.4.2 Contro# of Seepage 0#ow

4.4.$ owering of ater &a"#e6/27/16 2


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&e' !os *o+ , -$a. Roa/s Rai.i. o.20310121 5o./a" A*e.oo. a 6a+a./

WHAT I! THE 5AIN PR,7E59

WHAT D, Y,- THIN69

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4:1 I.o/cio. a./ I+poa.ce

o* Hi'a" Dai.ae !"se+

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4:1:1 I.o/cio. o* Hi'a" Dai.ae!"se+

WATER is the ain Cause of Deterioration ofHighway.

!a$ii" o* Hi'a"s is Re/ce/ $" eI.cease i. 5oise Co.e.s o* e !oi:

So Highways Drainage is ,SS,&I8.

D'8I89, is an I&,9'8 :8'& of the ,C**IC

HI9H8; D,SI9 and C*S&'


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Damage of Highway "y a

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Tee o* e 5os I+poa.

Aspecs o* Hi'a" Desi. ;

DRAINAGE

DRAINAGEa./

DRAINAGE:

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Wa is Hi'a" Dai.ae9

:rocess of 'emo)ing and Contro##ing the,=cess Surface and Su"-surface aterithin the 'ight-of-ay ('*+.

Inc#udes Interception and Di)ersion ofater from *)er>


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4:1:2 I+poa.ce o* Hi'a"Dai.ae !"se+

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1: !o*e.i. o* Roa/ !*ace (o* eae.: &e?i$e Pae+e.s &ai $" &o+aio. o*Waes a./ Coaio.:

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4: &e?i$e Pae+e. &ai $" &o+aio. o*Rs:

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: !ippi. o* 7i+e. *o+ Aeaes oose.i. o Deac+e. o* !o+e o* e7i+i.os a"es a./ &o+aio. o* Po

Hoes:

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Pooes &o+aio.

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: 5/ P+pi. i. Rii/ Pae+e.s

o)ement of materia# underneath the s#a" ore?ection of materia# from underneath the s#a" as aresu#t of water pressure.

ater accumu#ated underneath a :CC s#a" wi##pressuri@e when the s#a" deAects under #oad.

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3: Eosio. o* !oi *o+ Top !*ace o* Roa/sa./ E+$a.B+e. !opes De o !*aceWae:

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8: Co.si/ea$e Da+ae o !o/e a./ E/eo* Hi'a"s:

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6/27/16 $5


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: &aie o* Ea !ope o &o+aio. !opea./ E+$a.B+e. &o./aio.

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10: Eosio. o* !i/e !opes< Roa/ !i/e Dai.s remo)a# anddi)ersion of surface water from highwayand the ad?oining #and is Bnown asSurface Drainage System.

'emo)a# of rain water from road surfaceand road side ground is ca##ed SurfaceDrainage.

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CassiFcaio. o* Dai.ae WoBs

!*ace Dai.ae Surface Water isIntercepted and Diverted to a NaturalChannel or Depression.

!$s*ace o !$soi Dai.ae Seeping or Su"-surface ater is Interceptedand 'emo)ed to a Safe :#ace.

Coss Dai.ae WoBs ater of atura#Drainage


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Caeoiaio. o* !*aceDai.ae

1. Drainage in 'ura# Highway

2. Drainage in


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Dai.ae i. Ra Hi'a"

ater has to "e Drained *% oth from :a)ement withsucient cam"ering and Shou#der.

So Shoulders are Constructed with Suitable CrossSlopes so that the Water is Drained O to the SideDrains.

Drains are :ro)ided on ,ither Sides of the

'oad Eust 8d?acent to the Shou#der idth.

In &laces where Deep Open Drains are *ndesirable Dueto Restriction of Space +in cuttin%, a Covered Drain&roperl( )illed with $a(ers of Sand and -ravel !a( be

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Ca+$e


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48

Transverse slope

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Longitudinal slope

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50

Longitudinal channel

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Dai.ae i. -$a. !ees

Dri)ing Is#ands and 'oad Side De)e#opments.

Water Drained fro! the &ave!ent Surface can beCarried )orward in the $on%itudinal Direction'etween the erb and the &ave!ent for ShortDistances.

&his ater ay "e Co##ected in the Catch :its andead through


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D i i Hi R /


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Dai.ae i. Hi Roa/s

Catch Drains are :ro)ided 'unning :ara##e# to the

'oadway from which ater is Di)erted "y S#opingDrains and 8cross the 'oad :a)ement "y eans ofCu#)erts.

Side Drains are &rovided Onl( on the /ill Sides of theRoads not on the 'oth Sides.

Due to imitations in the 0ormation idth> the SideDrains are Constructed to such a S#ope that at,mergency the !ehic#es cou#d


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Desi. o* !*ace Dai.ae

Into 2 :hases-

1. Hydro#ogica# 8na#ysis

2. Hydrau#ic 8na#ysis

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H"/ooica A.a"sis


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H"/ooica A.a"sis

5ai. ,$ecies To Esti!ate the0a1i!u! 2uantit( of Water E1pected toReach the Ele!ent of Draina%e S(ste!*nder Consideration.

aios &acos AJeci. e R.oJae

'ate of 'ainfa##>

&ype of Soi# and oisture Condition>&opography of the 8rea>

&ype of 9round Co)er iBe !egetation> etc.

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Raio.a &o+a


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Raio.a &o+a

G run-o%>

C run-o% coecient (ratio of run-o% to rate of

rainfa##+ i rainfa## intensity mm/s

8d drainage area in 1555

C depends main#y on the type of surface and its s#ope.

Adconsists of se)era# types of surface run-o% coecients

C1> C2> C$> JJ with their respecti)e areas 81> 82> 8$> J.

&he weighted )a#ue of C =

Design )a#ue of i is to "e determined for the e=pectedduration of storm and freKuency of occurrence.

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&he in#et time for the storm water to Aowfrom the remotest point in the drainage

area to the drain in#et is estimated usingchart.

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&h ti f t t A th h th d i


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&he time for water to Aow through the drain"etween the in#et and out#et points isdetermined "ased on the a##owa"#e )e#ocity+%eneral ran%e fro! 3.4 to 5.6 !7s dependin%on the t(pe of soil, of Aow in the drain.

&he freKuency of occurrence of the storm orthe return period may "e > 15> 2 or 5 years.

&he drainage area from which the surface

water is e=pected to Aow to a side drain isdetermined with the he#p of contour map or "ystudying the topography of the drainage area.

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H /a ic A.a sis


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H"/aic A.a"sis

8fter determining the design run-o% QL> the ne=t

step is the hydrau#ic design of drains.

Side drains and partia##y ##ed cu#)erts aredesigned "ased on the princip#es of Aow throughopen channe#s.

If Q is the Kuantity of surface water to "e

remo)ed "y side drain and V is the a##owa"#e)e#ocity of Aow on the side drain> the area ofcross section Aof the channe# is found from there#ationF

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8ssuming uniform and steady Aow throughchanne# of uniform cross-sections ands#ope> 5a..i.Ls &o+a is used forca#cu#ating the )e#ocity of Aow or the#ongitudina# s#ope.

=here>

! a)erage )e#ocity> m/s

n annings roughness coecient' Hydrau#ic radius> m

S #ongitudina# s#ope of channe#

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&he roughness coecient )a#ues depend on thetype of soi# in un#ined channe#.

ae o* C

9ra)e# or 5.$ to 5.7

Imper)ious soi# 5.4 to 5.6

Soi# co)ered with turf 5.$ to 5.

:er)ious soi# 5.5 to 5.$

*rdinary earth 5.52

Hea)y )egetation 5.5-5.15

Concrete 5.51$

'ough ru""#e masonry 5.54

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Ta$e Ao'a$e eociies &o DiJee.5aeias

7e/ 5aeia

Ao'a$e

eoci"(+s)

si#t 5.$- 5.

oam 5.6- 5.

0ine sandy or sti% c#ay 5.- 1.

Coarse gra)e#> rocBy soi# 1.2 -1.

Soil covered with well established grass 1. - 1.3

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!i+piFe/ !eps *o e Desi. o*


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!i+piFe/ !eps *o e Desi. o*o.i/i.a Dai.s o* a Hi'a"

1. &he freKuency of return period such as 15years> 2 years etc. is decided "ased on thenances a)ai#a"#e and desired margin ofsafety> for the design of drainage system.

2. &he )a#ues of coecient of run-o%> C fromdrainage area are found and the weighted)a#ue is computed.

$. I.e i+e T1 for the Aow of storm water

from the farthest point in the drainage area

to drain in#et a#ong the steepest path of Aow6/27/16 73


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4: Ti+e o* Mo' ao. e o.i/i.a/ai. T2 is determined for the estimated

#ength of #ongitudina# drain Lupto the nearestcross drainage> and for the a##owa"#e )e#ocityof Aow Vin the drain i.e. T2 =.

. &he tota# time Tfor the in#et Aow and a#ong

the drain is taBen as e i+e o*co.ce.aio. o e /esi. ae o* ai.*a /aio.> T =T1+T2.

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h i f ## i i d i


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6. 0rom the rain fa## intensity-duration-freKuency cur)es> the rain fa## intensity is

found in mm/sec. corresponding to durationTand freKuency of return period.

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7. &he tota# area of drainageAdis found in units of 1555 m2.


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3. &he run-o% Kuantity Q is computed using 'ationa#0ormu#a Q = C i Ad.

. &he cross sectiona# area of AowAof the drain is ca#cu#atedA = where Vis the a##owa"#e speed of Aow in the drain.

15. &he reKuired depth of Aow in the drain is ca#cu#ated for a

con)enient "ottom width and the side s#ope of the drain.&he actua# depth of the open channe# drain may "eincreased s#ight#y to gi)e a free "oard. &he hydrau#ic meanradius of Aow Ris determined.

11. &he reKuired #ongitudina# s#ope S of the drain isca#cu#ated using mannings formu#a adopting suita"#e)a#ue of roughness coecient n.

= (5a..i.Ls &o+a)

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N+eica E?a+pes

5. The distance between the turf covered

draina%e area farthest point and point ofentr( to the side drain is 863 !. the avera%eslope of the area is 89. The avera%e valueof run o coe:cient is 3.86. The len%th ofthe lon%itudinal drain on the sand( cla( is6;3 ! +fro! the inlet point to the crossdraina%e,.. The allowable velocit( in the

drain is assu!ed to be 3.< !7sec ands 3.380annin%=s rou%hness coe:cient . Desi%n thecross>section and lon%itudinal slope oftrape?oidal drain assu!in% the botto! width

of the trape?oidal section to be 43 c!# free6/27/16 32


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!oio. Hi.s

I.e Ti+e () +for turf with 89 slope for 863 !

correspondin% distance fro! the chart, >> +i.

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20 +

>>


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&ime taBen (+ "y the storm water to Aowthrough the drain upto the cross drainage

M 5.6 m/sec or> 5.6 = 65 m/min 1 +i.

Toa Daio. o* Ti+e o Ti+e o*Co.ce.aio.

(&+ $$ N 1 48 +i.

Dai.ae Aea

(+ 45 = 25 1>$>555 or> 1> +5333

units,

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0 th ' i f ## I t it D ti C


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0rom the 'ainfa##-Intensity-Duration Cur)e>Corresponding Rai.*a I.e.si" (i+ for a

15 year period for 43 min 75 mm/hr or ++sec

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30

C 5.2 (9i)en+

G C 5 2 1$


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G C 5.2 = = 1$ sec

Cross-sectiona# 8rea of the Drain (8+ (1)

Since> 0or the &rape@oida# Section of Drain>

ottom idth of the Drain $5 cm 5.$ m

Side S#opes 1F1

et> the Depth of 0#ow d !>

then the &op idth (5.$ N 2d+ and the

Cross-sectiona# 8rea of the Drain O5.$ N (5.$ N 2d+P =

(5.6 N 2d+ = (5.$d N + (2)

&herefore> from (1+ and (2+>

(5.$d N + ------- or> N 5.$d Q 5

So#)ing this Kuadratic eKuation for d>

/ = +6/27/16 36

d d 11

11

5.$ m

d d5.$ m

(5.$ N 2d+

Cacaio. o* !ope o* Dai.


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the ongitudina# S#ope isca#cu#ated.

: 0or the 8ssumed &rape@oida# Section> the

etted 8rea of Cross-section 1:0 and the

etted :erimeter = 2 N 5.$ ------ +

-------

! = 5.6 = ------

S#ope > ! =

Since> 0ree oard cm 5.5 m

&herefore> Depth of the Side Drain may "e taBen as5. m N 5.5 m 0: +.

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4:>:1 DiJee. T"pes o* Roa/ !i/e


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Dai.

Surface drain Su" surface drain

ined drain


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4:>:2 Coss Dai.ae !ces (Ces a./


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4:>:2 Coss Dai.ae !ces (Ces a./,es)

hene)er the streams> ri)ers or watercourses ha)e to cross "y the roadwayfaci#ities> cross drainage structures are to"e proper#y pro)ided.

Sometimes these structures are used todi)ert the waterway from the road side

drain to a water course or )a##ey.6/27/16 2

T"pes o* Coss Dai.ae!ces


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!ces

1: CeQ when the #inear waterway R 6 m

2: 7i/e Q when the #inear waterway 6m

>: Case'a"sQ a##ow the water to Aow o)erthe roadway

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Ces


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C#osed conduit p#aced under theem"anBment to carry water across theroadway.

Cu#)erts #ead the water from the side drainsunder the road to the other (#ower+ side.

0itted with aprons> head and wing wa##s andinsta##ed with a simi#ar "acB##.

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Ce


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&.cio.s o* a Ce


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&.cio.s o* a Ce

&o co##ect and carry the water across theroad so as not to cause damage to road"anB or the stream "ed "y scouring.

&o a##ow sucient waterway to pre)entheading up of water a"o)e the roadsurface.

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T"pes o* Ces


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T"pes o* Ces

1. :ipe Cu#)ert

2. o= Cu#)ert

$. S#a" Cu#)ert

4. 8rch Cu#)ert

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Pipe Ces


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Pipe Ces

hen the stream carries #ow discharge and

a#ignment has high em"anBment> pipe cu#)ertsare considered more suita"#e.

:ipe is #aid s#ight#y inc#ined.

inimum diameter of the pipe cu#)ert is #imited to

655 mm to faci#itate c#eaning and a)oid "#ocBing. &he standard #ength of the 'CC pipe is =ed at

2. m> ?ointed "y co##ar or tongue and groo)e.

:ipes may "e made of stoneware> concrete> 'CC>

etc. &he standard si@e of pipe cu#)erts are 5. m> 5.7

m> 1 m> 1.2 m and 2 m in diameter.

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6/27/16 15$


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7o? Ces


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7o? Ces

o= cu#)ert of sKuare or rectangu#ar shape is

made of 'CC. 'ectangu#ar shaped cu#)erts Q referred to as "o=

cu#)erts - are common#y used to cater for #argercrossings.

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!a$ Ces


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!a$ Ces

'CC s#a" is p#aced o)er a"utments made of

masonry and the span is genera##y #imited to $ m.

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Ac Ces


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Ac Ces

9enera##y "ui#t using "ricB or stone masonry>

p#ain cement concrete may a#so "e used.

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Ae/c


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Ae/c

*pen or c#osed conduit sucient#y a"o)e the

roadway to drain water across the road.

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I.ee/ !ipo.


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I.ee/ !ipo.

Structure with #owering an in)ert #e)e# of conduit

across the road to desired #e)e# and "oth in#et andout#et pits are pro)ided to recei)e Aow from anddischarge water to the downstream drainrespecti)e#y.

In)erted siphons (a#so ca##ed depressed sewers+a##ow storm water to pass under o"structionssuch as ri)ers.

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Case'a"


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Case'a"

:ro)ided instead of cu#)erts on #ess important

road which sa)es the construction cost. :ro)ided where the ma=imum depth of Aow does

not e=ceed 1. m.

ay "e High e)e# (Su"mersi"#e ridge+ or ow

e)e# (Irish ridge+

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Hi ee Case'a" (!$+esi$e

7 i/ )


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7i/e) Guite a"o)e the stream "ed and is pro)ided with

)ents to a##ow norma# Aoods to pass throughthem.

During hea)y Aoods> causeways may underwater.

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o' ee Case'a" (Iis 7i/e)


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" ( )

Constructed at the "ed #e)e# of the stream whichremains dry for most of the time.

8#so ca##ed o' Wae Cossi.> case'a"in8ustra#ia> o' ee Cossi.or o' Wae7i/eor Irish ridge.

:ro)ides when water Aow is #ow. water runs o)er the

roadway and stops the )ehicu#ar trac.

&his approach is cheaper than "ui#ding a "ridge to

raise the #e)e# of the road a"o)e the highest Aoodstage of a ri)er> particu#ar#y in de)e#oping countriesor in semi-arid areas with rare high-)o#ume rain.

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7i/es


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Structure constructed o)er water course tocarry trac o)er it.

hen c#ear span is more than 6 m> thecross drainage structures are ca##ed"ridges.

Acco/i. o !pa. e.

8+ inor ridge F Span ength upto $5 m

+ a?or ridgeF Span ength $5 m

C+ ong ridgeF Span ength 125 m

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4:>:> DiJee. T"pes o* E.e" Dissipai.!ces


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!ces

8t out#et of cross drainage structures>there is a#ways higher )e#ocity than non-scouring )e#ocity which shou#d "e

adeKuate#y contro##ed.

any measures suita"#e at di%erent#ocations and conditions for Contro##ing,nergy and ,rosion.

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T"pes o* E.e" Dissipai.!ces


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!ces

ining Drains

) Ditch ChecBs

) 0a## or Drop Structures

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4:4 !$s*ace Dai.ae !"se+


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Change in moisture content of su"-grade are caused"y Auctuations in ground water ta"#e> seepage Aow>perco#ation of rain water from shou#ders> pa)ementedge and soi# formation s#opes and capi##ary rise ofmoisture and e)en moisture )apour through soi#.

In su"-surface drainage of highways> it is tried to Beepthe )ariation of moisture in su"grade soi# to aminimum.

*n#y the gra)itationa# water is drained "y the usua#drainage systems.

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4:4:1 Dai.ae o* I.Fee/ Wae


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y pro)iding suita"#e su"soi# drainage system.

Su"soi# drain trenches are e=ca)ated to "e#owsu"grade #e)e#

T"pica !$soi Dai.


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T"pica !$Pae+e. Dai.


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&o./aio.Dai.s

4:4:2 Co.o o* !eepae &o'


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hen the genera# ground and imper)iousstrata "e#ow are s#opping> seepage Aow is#iBe#y to e=ist.

If the seepage @one is at depth #ess than5.6 to 5. m from the su" grade #e)e#


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4:4:> o'ei. o* Wae Ta$e


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Highest #e)e# of water ta"#e shou#d "e "e#ow thesu"grade.

T :ractica##y 1.5 to 1.2 m "e#ow su"grade

T 'e#ati)e#y permea"#e soi#- ongitudina# drains are main#y used

T Impermea"#e soi#s-

&rans)erse drains may "e necessary in addition to#ongitudina# drains

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4:4:4 Co.o o* Capia" Rise


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If the water reaches the su" grade due to

capi##ary rise is #iBe#y to "e detrimenta#> itis possi"#e to so#)e the pro"#em "yarresting the capi##ary rise instead of

#owering the water ta"#e.

2 types of capi##ary cut-o%s can "e used.

8+ 9ranu#ar Capi##ary Cut-o%

+ Impermea"#e Capi##ary Cut-o%

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Desi. o* !$s*ace Dai.ae !"se+


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&he si@e of spacing of su"surface drainagesystem wou#d depend on the Kuantity ofwater to "e drained o%> the type of soi#and type drains.

ost#y this is decided "ased on e=perienceand other practica# considerations.

Howe)er> proper #ter materia# shou#d "eused for "acB ##ing the drainage trenchesand a#so for use in a## su"surface drainage6/27/16 174

5iscea.eos Eosio. Co.o5eases


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!egetation on S#opes of ,m"anBment Dry Stone :itching

9a"ion Crates 0i##ed :itching

Stone asonry 'etaining a## Concrete #ocB ining

'etaining a## with 9a"ion Crates

anB :rotection Spurs and ChecB Dams

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Desi. o* &ie 5aeia


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&he #ter materia# used in su"surface drain shou#d"e designed to ha)e sucient permea"i#ityo%ering neg#igi"#e resistance to the Aow.

&he #ter materia# shou#d a#so "e designed to resistthe Aowing of the ne foundation soi# resu#ting inpro"#em #iBe piping.

Hence the grain si@e distri"ution of #ter materia# isdecided "ased on these two criteria of permea"i#ity

and piping.

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The procedure for desi%n of Blter is brie( discussed below>

1. *n a grain si@e distri"ution chart p#ot the grain si@edistri"ution cur)e for the foundation soi#.


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2. 0ind the )a#ue of D1 si@e of foundation materia# and p#ot apoint of partic#e si@e D1 of foundation to represent the #ower

#imit of D1si@e of #ter. &his to fu### the permea"i#ity condition

gi)en "yF- (D1of #ter / D1of foundation + shou#d "e .

$. &o fu### the condition to pre)ent piping F- ( D1of #ter / D3offoundation + shou#d "e #ess than ( U + > hence p#ot a point torepresent the upper #imits of D1 si@e of #ter gi)en "y D3 of

foundation.

4 0ind the si@e of perforation in the drain pipe or the gap in the

4. highway drainage -lecture version 073.pptx

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