-
COIVCRETT SOCIEIY" TECITrVICAL-?APIIR "IvO 1O5
F. A. Auld BSc, PhDictCflngi:,MIGE.t::,MIMi,f]E ;-;, iFFBC h i e
f D e s i s n E n s i n e e r .
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r , : j , . r i : j r. j , - r n , l . ' , , : , , r i 5 ' - . '
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; s b ( r ' : ' r i x i l t j
r . i i . j j r j l ! : t , 1 1 ! ; . - ; - i t l t : j ; l { i
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i ' i : . i , r i i : ! : f ) , : i z : t i a i ; t i I i d ; l
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r l l r t 1 i ) r 5 : ! f v r a ) a w ( r l i , i r . ' i r , r
: i l : r , l i ' : l i l l l . i , : i l . i r
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Terminal House, Grosve,no.,_r:. Gardens3e LortdonrSWilW!{ OA,JI
-".)t.;a.i lThe Conc re te Soc ie t y ,
-
The author wlshes to thank Mr J C Black, ManaglngDirector of
Cenentat ion Hlnlng Lin l ted, forpernisslon to present the paper.
I l lustrat lons anddetal ls are inc luded f ron the Selby New
MineProjecc and the author ls lndebted toMr C T Massey, Deputy
Dlrector ( l { in ing) - SelbyProject , of the Nat lonal Coal Board
for h ispernisslon to use th ls lnfornat ion.
Further acknowledgenents are due to Mr V W l lowe,who was
responslble for producLng nany of thei l l u sc ra r i on d raw
lngs , Cemen ta t l on M ln l ng L lm i t ed rsdrawlng of f lce
personnel for assistance lndetai l ing others, Mrs J Slmpson for
prLntLng chei l lustrat lons, Mrs M Mordue for typlng themanuscr
ipt , and var ious col leagues in Cenentat ionMlnlng Lin i ted for
supply ing the photographs.
Fronc cover photograph: Typical shaf t bot ton showingactual
worklng condi tLons. Mount Isa Copper Mine,sha f t A .10 .S , Aus t
ra l i a .
Concrete Soclety Technical Paper.No. 105
Flrst publ lshed 1983 -
ISBN O 72LO T284 I
Publlshed by The Concrete SocletyTerninal House, Grosvencir
Gardens, London SWIW OAJ
Designed and prlnted by the Cement and ConcreteAssociat
ionWexhan Springs, Slough SL3 6PL
Further copl-es nay be obtained fron:Publ lcat lons Dlstr lbut
lon, CeEent and ConcreteAssocl .at ionI{exham $prlngs, Slough SL3
6PLquot lng' reference nunber 53.039
Price Group CS5
@ fne Conc re te Soc te t y 1983
Although The Concrece Soclety ( l in l ted byguarantee) does l
ts best Eo ensure Ehat any advice,recoomendat ion or lnfornat . ion
i t nay glve el ther Lnthis publ lcat lon or e lsewhere is
accurate, nol l ab l l l t y o r r espons ib i l i t y o f any k i
nd ( t nc l ud ingl tabl l l ty for negl lg6nbe), howsoever and f
ronl thaEsoever cause ar is lng, ls accepted ln th isrespec t by t
he Soc le t y , l t s se r van t s o r agenEs .
-
Goncrete inUnde$rorrnd.IllorlcsF. A. Auld BSc, PhD, CEng, MICE,
MIMinE, FFBChief Design Engl-neer ,Cenentat ion Mln ing L in i
ted
Paper p resented a t The Concre te Soc ie tyYorkshire and
Hunberside Reglon.One-day Synposlun, Concrete in power andenergy .
Se lby Fork Hote l , Yorksh i re
18 Novernber 1981
The paper covers three aspects ofconcret ing in underground
works.
I n t he f i r s t sec t i on , va r i ous t ypes o fs t ruc tu
re a re desc r i bed to i l l us t ra tethe broad range of
concreteconstruct ion work which is involved inmining development .
An indicat lon ofgene ra l des ign p r i nc ip les i s a l soinc
luded .
The secbnd sec t i on i l l us t ra tes t hemeans of carry lng
out the work. Plantand cons t ruc t i on t echn iques a redesc r l
bed i n de ta l l .
A d i scuss ion on m ix des ign requ i remen tscons t l t u tes
t he th i rd aspec t . I nc ludedin th is sect ion are commenE.s on
the useof cement replacement mater ia ls andadmix tu res .
-
eutfror's Introductorywote onRecent and.GurrentUndeground.Worlcs
ProjectsCenentat lon Mlnlng Lin l ted have ln the last f iveyears
been lnvolved ln the conscruct lon of s ixsha f t s ( ou t o f a t
o t a l o f t en ) and t so d r i f t s f o rthe Nat lonal Coal
Board's New Mlne ProJect at Selbyl n Yo rksh l r e ( see F igu re 1
) . Sha f t dep ths rangefrom 417 to 1033 n. The Gascolgne Wood dr
l f ts andlwo shaf ts at WlsEow are norr complete, wi th theother
four shaf ts, cwo at Rlccal l and two ar NorthSe lby , s t l l l
unde r cons t ruc t l on a t t he p resen tt loe. AI I the shafEs
at Selby have been sunk uslngthe f r eez lng p rocess t o con t ro
l wa te r , t he dep thsof f reeze ranging f ron 148 to 283 n.
Cenentat ionMlning Lin i ted are also ready to conmence s inklng,w
i t hou t f r eez lng , a new 1023 ro deep sha f t a t Ma l t byCo
l l i e r y f o r t he NCB.
Du r i ng t he pe r i od 1963 t o 1973 , e i gh t sha f t s we
resunk for Ehe potash nines ln Saskatchewan, Canada,by The CeEen ta
t l on Co . (Canada ) L td . , s l x o f t hento dep ths o f ove r
1000 n n i t h f r eeze dep ths f r om468 t o 684 n . Many o the r
sha f t s have been sunkove r t he l as t lwen t y yea rs t n va r
i ous coun t r l esw iEh o r s i t hou t f r eez lng . I n Ge rnany
, s i x t eenshafts have been sunk dur ing the per lod using thef
reez ing p focess , f ou r o f t he@ cu r ren tcon t rac t s 1 . A
t o ta l o f t h i r t y -one sha f t s havebeen constructed in
Canada and Norrh Aoer ica s lnce1963 uslng f teezlng 2. The Chinese
have also sunkr n o r e t h a n s e v e n t y s h a f t s , a l l f
r o z e n 3 .
Annua l l eng ths o f 56 and 47 .3 ko a re quoced f o rl l ned
and un l i ned t unne l s f o r t he yea rs 1979 and1980 respec t l
ve l y a . Du r i ng t he l as t f i f t een yea rsCeEentat ion
Mlning LiEi ted have been theconEractors for che Alcan Snel ter
polrer staEioncoo l l ng wa te r i n t ake and ou t f a l l t unne
l s a tLynenouth, the two Is le of Grain pouer sta i ioncool lng
sater lntake tunnels and the s inglePeterhead power stat ion cool
ing water intaketunne l . I n 1978 t hey a l so comp le ted t he Ed
inbu rghe f f l uen t ouc fa l l t unne l w iEh twen t y d l f f
use rs ! othe sea bed ln Seaf le ld Bay. At leasE two noresuch con
t rac t s a re cu r ren t l y l n p rog ress by o the rc o n t r a
c t o r s .
The f u tu re po ten t i a l f o r sha f t , t unne l
andunderground construct lon is enormous. Access belowg round l s r
equ i r ed f o r nany pu rposes : e .g :
n i ne ra l ex t r ac t i on ;power s t a t i on and assoc la
ted f ac i l l t i e s ( coo l i ngwa te r t unne l s and nach lne
ry ha l l s ) ;e f f l uen t r eoova l t o t he sea ;s t o r a g e
( g a s , l i q u i d o r n u c l e a r w a s t e ) ;nuc lea r she
l t e r s .
Al though aE the present t lne the wor ld-vLdeeconornic c l
lnate is no! favourable for suchdeve lopoen t , nany f u ru re na
jo r p ro j ecEs a rei nev l t ab le .
F A AuIdOc tobe r 1982
References[ . KLE IN , J . P reaen t 6 ta te o f f r eeze sha f
t des lgn
ln n ln lng. Proc. of the Synposiun on StrataMechanlcs, Univers
i ty of Newcast le upon Tyne, 5-7 Ap r l 1 , 1982 . E l sev le r Sc
ien t l f l c Pub l l sh l ngConpany , 1982 . pp . 147 -153 .
BRAUN, B. and NASII , W.R. Ground f reezLngappl icat lons ln
underground nin lngcons t ruc t l on . P roc . o f The Th i r d I n
te rna t l ona lSynposiuro on Ground Freezlng. US Arruy Corps
ofEngineers Cold Reglons Research and Engln-eer ingLabo ra to r y ,
Hanove r , New Hampsh l re , USA . 22 -24J u n e , 1 9 8 2 . p p .
3 1 9 - 3 2 6 .
AULD, F.A. Notes on v is l t of Cementat ion MlnlngLlnl
ted/Foraky Lln i ted Technlcal Delegat lon toC h i n a , 3 - 1 5 O
c t o b e r , 1 9 7 9 .
CONSTRUCTION INDUSTRY RESEARCH AND INFORMATIONASSOCIAT ION. R .P
. 307 - P ipe Jack ing Phase 1 .Second Draf t Report . Chapcers 1,
2 and 3 andAppend i x A , B , and C . Ap r i l , 1982 .
4 ,
-
Gontents
I.IntroductionaIVI,es of Stnrcture and.
Generaf Desi$n FinciBles 4In t roduct ion
Sha f t s
2 .2 . I Advan tages o f conc re te i nshaf t construct ion
2 .2 .2 Re in fo rcemen t2 . 2 . 3 D e s i g n o f s h a f t l i
n i n g s
2.3 Co l la rs and fo reshaf ts
2 .4 A i r and fan dr i f t s
2 . 5 I n s e t s
2 . 6 T u n n e l s
2 .7 Sp i ra l chu te bunker shaf ts
2.8 Sump tanks
2 . 9 P l u g s
4
6
2. r2 . 2
4. Goncrete llltix Design4 . 1 I n t r o d u c t i o n
4.2 Normal mixes
4.3 Cement rep lacement mater ia ls
4 .4 Admix tu res
5. Gonclud.lng Remarks6. Eeferences
666
6
8
t0
l1
I4
16
l6
t7
17
t7
IB
r8' ) L
z o
28
2B
2B
2B
292929
30
30
J U
3 l
3 l
3 3
3 4
5. Construction MetJrod.s3.1 In t roduc t ion
3.2 Co l la rs and fo reshaf ts
3 .3 A i r and fan dr i f t s
3 .4 Shaf t l in ing
3 . 5 I n s e t s
3 .6 Tunne ls
3.7 Spiral chute bunker shafts
3.8 Sump tanks and plugs
3.9 Batch ing p lan t
3 .10 Transpor ta t ion and p lac ing
3.10 .1 Transpor ta tLon down shaf ts3 .10 .2 Transpor t
underground3.10 .3 Concre te p lac ing a t roo f leve l
Page
4
7. GlossarJr of llfiining Terms :s
-
l.IntrodustionConcrete and steel are the two najor
construcElonnater la ls used in underground developnenc work.Steel
ls nornal ly enployed ln the forn of arches orsquare work (colunns
and beans), fabr l .cated f ronstandard secElons. Archee or square
sets roay beused as pen0anent support to an excavat lon or
astemporary supporE prLor to provld ing a peroanenEconcrete
structure. Except in extrenely competentand sel f support lng
ground, or Ln ground whlch canbe supported by rock bol ts and nesh,
steelworkcenpo ra ry suppo r t , p r l o r Eo l l n i ng l n conc
re te , l sessen t i a l f o r sa fe wo rk i ng 1n unde rg
roundexcava t i ons .
UsLng concrete underground creates addl t lonalproblens to Ehose
encountered above ground,
Conf lned spaces present access, handl lng andpJ.acing problens
and. for developnent sork inex l sE lng p i t s , i t s use ous t
no t i n t e r f e re w l t h p l tp roduc t l on . Neve r t he
less , wLch a co r rec l l yenglneered handl ing systen, the r lght
p lant and asulEable nlx deslgn, concrecLng underground Ls noEd i f
f i c u l t .
Thls paper concentrates on three naLn aspecte ofunde rg round
cons t ruc t l on w i t h conc re te . F l r s t l y ,l t i l
lustrates the types of sf ructure which can befound ln such an
envlronnent. Also lncluded aregene ra l des lgn p r l nc l p l es f
o r such s t r ucL . l r f es . Thesecond sec t i on desc r l bes
how cons t rucB lon wo rk o ft h l s k i nd i s ca r r i ed ou t .
F l na1 l y , conc re te D l xdes lgn requ i r enen t s a re l nd l
ca ted . I n che l a t t e rsecl lorr , the use of cenent
replacement Eater la lsand adnlxt .ures ls conmented uDon.
a IIrI,es of Stnrcture and, @neral Desilfn Pr'rnciples2 . 1 I n
t r o d u c t l o n
In s inple terms, underground development workl nvo l ves ch ree
d i s t i ncc s tages o f ope ra t l on ( seeF igu re l ) . Fo r a
new n ine , t he f i r s t s t age l s t hesinklng of a shaf t or
an lncl lned dr i f t to reachthe level of the proposed
undergrounddeve lopnen t . Second l y , ho r i zon ta l o r nea r l
yho r l zon ta l t unne l s a re d r l ven Eo t he ex t r ac t l
onface o f t he o re body . Th l r d l y , pa r t l cu l a r a
reasalong the dr ivage are enlarged to house equipoentand o the r p
roduc t l on f ac i l l t i e s . The cons t ruc t l ono f o the r
unde rg round s t r uc tu res wh i ch a re r equ i r edi s a l so l
nc l uded i n t h i s l as t sEage . F i gu re 2shows nany of the
structures to be found ln a n lne.
Civ l I englneer lng shaf t s inking and tunnel l lng worki s ca
r r l ed ou t i n s i n l l a r s t ages t o t ha t f o r a newmlne
. Ex i s t l ng p l t deve lopnen t l s pu re l y anex tens lon o f
f ac l l i t l e s on t he saoe bas i s .
F i i u r e 1 .
4
To put the use of concrete underground lntoperspect ive, i ! t
rust be reroeobered Ehat the nln ingenv i r onmen t f t nposes l t
s own spec ia l cond i t l ons .A l l i ed r l l t h any excava t i
on l s a cons lde ra t l on o ftwo naJo r f ac l o r s :
( a ) The s tab l l i t y o f t he excava t l on once l t i
sopened up ,
(b ) The poss ib l e p resence o f waEe r l n l a rgeq u a n t i
t i e s .
Eo th o f t hese aspec t s can be s tud ted p r l o r Eoexcava t
i on , us i ng geo log l ca l and hyd rogeo log l ca lbo reho le da
ta , and t he t r e thod o f g round p re -t r ea tnen t can be es
rab l l shed . P rov l ded t he wa le ri n f l ow i s l ow l t can
be hand led en t i r e l y by d l r ec tpunp ing o r w l t h t he
ass l s t ance o f a we l l dewa te r l ngs c h e m e .
I f t he s tud ies i nd i ca te t he p resence o f l a rgequan t
l t i e s o f l r a t e r , t hen p re - t r ea toen t by g rou t i
ng
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W i s t o w
S t i l l i n g f t e e t
R i c c o l l
Wh i l emoo r
No r l h Se tby
New m ine cons t rucE lon - t he deve lopnen t o f t he Se lbv
Coa l f i e l d .
-
( 1 )
@
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LEGENDH e o d f r o m e
S k i p h o i s t i n g o n dd i s c h o r g e s y s t e m
S h o f t c o t t o r
F q n d r i f t
V e n t i l o t i o n f q n
S h o f t f u r n i s h i n g
S h o f t t i n i n g
I n s e t s
o@( 1 1 )
@@@
@
S k i p t o o d i n g p o c k e t
P u m p c h o m b e r
S u m p t o n k
S o f e t y p t u g w i t hb u t k h e q d d o o r
S p i t t o g e r e m o v q t
R o o d w o y j u n c
B u n k e r s h q f t s
F igu re 2 . M ine s t r uc tu res and ope raE iona l f ac i l i
t i e s .
-
t ray be necessary to reduce the Lrater nake lnto thee x c a v a
t l o n . G r o u t l n g l s t h e p r o c e s s o f l n j e c t i
n gc e m e n t , o r o t h e r m a t e r i a l s , t o i o p r o v
e t h e s t r e n g t ho f t he s t r a te o r t o r e ta rd o r p
reven t t he passageo f l i q u i d s o r g a s e s . F o r e x c e
s s l v e a n o u n t s o fwa te r l n cond i t i ons whe re t he g
round i s no tsuscep t i b l e t o g rou t i ng , f r eez ing t
echn iques can becons ide red . The f r eez lng p rocess i s a l
onges tab l l shed me thod o f conso l i da t l ng wa te r -bea r i
ngs t ra ta t o p repa re i t f o r sha f t s i nk i ng , l n wh i
ch af r eez ing agen t ( usua l1y b r l ne ) i s c i r cu l a tedt
h r o u g h s u i E a b l y d i s p o s e d b o r e h o l e s d r i
l l e d i n t othe s t r a ra a round t he s i t e o f t he sha f t
. S i t r l l a rt echn lques can a l so be emp loyed i n t he ho r
i zon ta ld i r e c ! i o n f o r t u n n e l s .
I t ls l r iEhin th ls envlronnent that concrete must
betransported and placed underground. Ful l knowledge1s t he re fo
re essenE ia l o f t he behav lou r o f conc re tel n a l l ch ree
phases o f 1 t s i ns ta l l a t i on , l n f he weEsEa te r du r i
ng l n i t i a l se t t l ng and i n t he f u l l yha rdened cond i
t Lon .
The Eethod of excavat ing is an added factor to beconsLde red
when us l ng conc re te unde rg round .B las t l ng i s no rna l l
y e rnp loy i d and i t s e f f ec t s onear ly age concrete at c
lose range EusE beacconnoda ted . The sub jec t o f b l asc i ng e
f f ec r s onear ly age concrete ls a conplex one and lst he re fo
re ou t s i de t he scope o f t h t s pape r .
I n add iC ion t o g round t r ea tmen t , t he l i n i ng o f
anexcavat ion can also be designed pr ior tocons t rucE ion by enp
loy i ng . rock and so i l mechan l csp r l nc l p l es Eo de te rn
i ne g round p ressu res o r on t hebas l s o f t he l i n i ng rs
ab l l iEy t o r es l s t hyd ros ta t i cp ressu re . Conc re te l
i n l ngs i n t h l s con tex t cane i t he r be pu re l y cosne t
l c whe re l he g round i s se l f -suppo r t l ng ; t hey nay be
cons t ruc ted a f t e rl nsca l l l ng s tee lwo rk t empo ra ry
suppo r t ; o r t hedes ign cou ld necess i t a te r ap id l ns ta
l l a t i on ,lnnediately upon openlng up the excavat ion, tonln in
ize ground movement.
2 . 2 S h a f t s
A t yp l ca l sha f t sec t l on i s i l l u s t r a ted i n F i
gu re 3 ,t oge the r w i t h t he geo logy and esE lmaEed wa te
rlnf lows needed for ground pre- t reatment analysisand sha f t l i
n l ng des lgn .
2 . 2 . 1 A d v a n t a g e s o f c o n c r e t e i n s h a f
tcons t ruc t i on
The cho i ce o f conc re te as a sha f t L i n i ng ma te r i a
li s eas i l y Jus t l f l ed . Re la t i ve l y sma l l a reas o
fwa l l can be cons t ruc ted sys tema t l ca l l y i n phasew l t
h t he sha f t s l nk l ng p rocess . T ranspo r t t o anypos i t l
on i n Ehe sha f t i s s l np le by neans o fp i pe l l ne o r sk i
p . Conc re te i s a conven len tnaterLal to handle and place r .
r1 lh in fhe restr ic tedwork l ng space o f a o l ne sha f t .
When p l aced ,conc re te mou lds i t se l f t o Che excava ted p
ro f i l e o fthe shafE provld ing an inEer locking act ion wi th
thesu r round ing rock . TesE ing p rocedu res f o r conc re tequa
l i t y con t ro l a re s t r a i gh t f o rwa rd . Res i s t ance
t osulphate at tack is achieved by using sulphateres i s t i ng Po
r t l and cenen t , p roduc ing a s t r uc tu rewh l ch requ i r es
l i t t l e na in tenance .
Un re ln fo r ced conc re te can w l t hs tand mos t l oad
ingcond i t l ons no roa l l y encoun te red and 1 t p roduces ad
ry ' sha f t . T t r e bene f i t s o f us i ng conc re te ,pa r t
l cu l a r l y un re i n fo r ced conc re te , f o r sha f tI i n l
ngs a re t he re fo re subs tan t i a l .
2 . 2 . 2 R e i n f o r c e m e n tSEee l r e l " n fo r cemen t
i s used on l y l n spec ta lc l r cuns tances , whe re weak s t r
a ta occu r , t o p rov i deres l s t ance t o l oca l i sed t ens
l l e bend ing s t r essesand as a means o f p reven t i ng f r
agmen ta t l on o f t heconc re te , Howeve r , s t ee l r e i n fo
r cenen t wh i ch hasCo be included ln a shaf t wal1 could be
subject toco r ros i on wh l ch cou ld cause spa l l l ng . I n add
i c i on ,t .here is a probleo ln f ix ing the re lnforcement
and
so , l n gene ra l , i t l s p re fe rab le t o useun re ln fo r
ced conc re te .
2 . 2 . 3 D e s i g n o f s h a f t l i n l n g sThe des lgn o f
conc re te sha f t l i n i ngs i s d i scussedroo re f u l 1y i n o
the r pape rs r , z . S t r esses i n ath lck cyl lnder can be
deternlned eicher on ane las t l c des ign bas i s o r by an u l t
i na te l i n l t s t a teapp roach eop loy i ng p l as t l c l c y
p r i nc i p l es . I n Ehecase of a shaf t ln conpetenE (sel f s
tanding whenexcavated) rock, the deslgrr of the l ln ing need
onlyca te r f o r hyd ros ta t l c p ressu re t h rough t he aqu i
f e rzones . The t h l ckness o f t he l l n l ng i s t he re fo
revar ied wi th depth unt i l a level ls reached at whichsater is
no longer present and only a noninalt h l ckness o f conc re te
becones necessa ry . M lg ra t l onof wacer downsards f ron the
hydrostat ic sect lon lsp reven ted by l ns ta l l l ng g rouc sea
l s a t t he ' bo tEono f t he hyd ros ta t l c l l n l ng . I n g
round wh i ch l slncompetent , rock pressures may need to becons
lde red as an a l t e rna t l ve t o hvd ros ta t i c
P res su re .
The mlninun th ickness for a concrete shaf t l in lngls norual
ly 300 nn unless che concrete is belngcas t . d l r ec t l y aga
lns t f r ozen g round , l n sh i ch case600 oo should be the
mlnLroun. Wlth th ls extrath i ckness o f conc rece su f f l c i
enc hea t i s gene ra tedby the hydrat lon of Ehe cenent to
overcome anyde t r l oen ta l e f f ec t s due t o f r eez ing o f
t heconc re te . I nc renen t s o f wa1 I t h i c kness o f 150
nmare gene ra l l y used , up t o a nax lnum o f 1200 m , a twh i
ch t h l ckness cons t ruc t l on beconeslnp rac t l cab le . Spec
l f i ed cha rac te r i s t i c s r r eng thsfo r sha f t l i n l
ng conc re te r ange f r om 25 N /mm2,sh l ch i s che l ose r l im
i t f o r dense , wa te r t i gh t ,s t r uc tu ra l conc reEe , up
t o 45 N /mn2 , t h l s be ing t hep racE i cab le uppe r l l n i t
bea r i ng i n u r t nd t hecon f l ned cond l t i ons o f p l ac i
ng . Howeve r , w iEhapp rop r i aEe n i x i ng red iencs and by us
i ngworkab l l l t y agen t s and good qua l l t y con t ro l ,sE
reng ths g rea te r t han 45 N /nu rz a re poss ib l e .
L in ing of the shaf t takes place downwards in 6 mleng ths as s
l nk l ng p roceeds . PVC g rou t sea l s(F lgu re 3 ) a re p rov i
ded a t each cons t ruc t i on j o i n tand coup le te na te r t i
gh tness l s ach ieved us i ng abackwa l l g rou t i ng p rocess .
F ron F igu re 3 i t cana l so be seen t ha t a t each ho r i zon
ta l j o i n t i n anyf r o z e n s e c t l o n a s l o t i s l e f
E a t t h e i n s i d e f a c ewhich can be gunl ted af ter conplet
lon of heavedu r l ng Ehe f r eez ing pe r i od . Gun i t i ng i s
ca r r i edout f tnmediately the cenperaEure of the l ln lng r
lsesabove 0"C in the thawing per iod. The cr ibs shownln F igu re 3
p rov i de add i t l ona l suppo r t f o r t heseight of the l in
ing Ehrough sof ter zones butnorrnal ly the weight is assumed to be
t ransferredd i r ec t l y t o t he su r round ing rock .
2 .3 Co l l a r s and fo resha f t s
Pos i t l oned aE t he t op o f t he sha f t l l n l ng l s t
heco l l a r and f o resha f t s t r uc tu re ( see F igu re 3 )
.Th i s i s cons t ruc ted i n r e l n fo r ced conc re te ( seeF
igu re 4 ) . The t o ta l l eng th o f Eh l s sec t i on , f r
oocol lar level to the bot ton of foreshaft wi l l varydepend ing
upon t he g round cond iE ions . Wa l1th l cknesses a re no rma l l
y g rea te r t han f o r t heuppe r sec t l ons o f t he sha f t l
i n i ng . F i gu re 5 l sa v le l r looking down a f in ished col
lar andfo resha f t .
The pu rpose o f t he co l l a r and f o resha f t l stwo fo l d
. I t s ma ln f unc t i on l s t o p rov l de a r i g i d ,I oad ca
r r y i ng s t r ucCu re wh l ch passes t h rough t heso f t , su r
f ace so i l depos l t s and t r ans fe r s t hehead f rame and o
the r co l l a r l oads t o t he ha rd ,conpe ten t r ock be low .
I n o the r wo rds i t pe r f o rmsthe f uncE ion o f a l a rge d l
ame te r p l l e . Theseconda ry f unc t i on o f t he co l l a r
and f o resha f ts e c t i o n i s t o g i v e s u f f i c l e n t
i n i t i a l d e p t h o fsha f t co enab le t he i ns ta l l a t
i on o f t he s l nk i ngs tage t o be ca r r i ed ou t p r i o r t
o t he Ea lnexcava t i on .
-
FREEZE
FROZENI \zoNr i
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STOT 6UNITEOAFTER THAW
H I G HPRESSUREPV.C. SEAL
CONSTRUCTION JOINT OETAIL
NOHINALWAL LTH ICKNESS
6ROUPIPES
GRAVEL RETAINEOBEHINO STEELSHEETI N6
SPEI IAL 6ROUT R IN6 OETAIL
2273to 227)0
( 500to 5000)
STANOARD
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I N S E T
F lgu re 3 . Sha fE sec t l on ' t ' l t h geo logy and es t i
naEed r . r aEe r l n f l ows , No r t h Se lby No . 2 ( upcas t )
sha f t .
-
o-rifo t-"."r'
I-e
o io l*i
S E C T IIO N A - A
S E C T I O N B - B
t-
S E C T I O N C - C
F igu re 4 . Co l l a r and f o resha fE s t r uccu re w i t h f
an d r i f t en t r y , Se lby R i ca l - l No ' . 2 ( upcas t )
sha f t .
In addl t lon to belng able to wi thstand al l lnposedloads , bo
th ve r t l ca l and ho r i zon ta l , a t co l l a rl eve l , t he
co l l a r and f o resha f t a re des igned t ores i s t g round
and wa te r p ressu res ac r i ng rad la l l yon t he s t r uc tu
re , wh i ch l nc rease w i t h depEh . Thec r i b s i t ua ted a t
t he base o f che f o resha f t ass i s t sl n sp read ing t he ve
r t i ca l l oad a t t h i s l eve l ove r al a rge r a rea , r
educ ing t he bea r i ng p ressu re , as we l las p rov i d l ng an
add l t i ona l key l n t o Ehe s t r a ta .
2 .4 L f t and fan d r i f t s
Hine ven t l l a t l on l s a ve r y i npo r t an t aspec t o
funde rg round ope ra t l ons . No rma l l y sha f t s a re sunkin
pa l r s , one f o r r n l ne ra l w ind ing and t he o the r f o
rnen and oa te r l a l s access . As a seconda ry f unc t i on
,
8
ter ln shaf ts a l low one Eo be used for a i r entry andthe
second for a i r exhausE. Entry and rernoval ofa l r nay t ake p l
ace t h rough t he head f rane bu l l d i ng ,founded at col lar l
-evel , or v l .a an incl , lned dr l f tw i t h a s l de en t r y
i n t o l he co l l a r and f o resha f ts t r uc tu re be low g
round l eve l . F l gu re 6 i l l u sE ra tesa re i n fo r ced conc
re re exhaus t f an d r i f t f o r a sha f ti n wh l ch t he a i r
Ls upcas t . A s l n l l a r s t r uc tu re ,l e rned an a i r d r
i f t , wou ld be p rov l ded f o r a l ren t r y t o t he downcas
t sha f t .
The des ign o f a i r and f an d r l f t s f o l l ows s tanda
rdbasLc p rLnc lp l es . S ince one end i s a t t ached t o ar i g
l d f oundaE lon - t he sha f t - s l n i l a r suppo r t mus tbe
provlded over the reoainder of the dr i f tl engEh . The re fo re l
n a l l cases o the r r han ha rdrock p l l ed f ounda t l ons a re
necessa ry .
-
F igu re 5 .
Design is based on the analysis of the box cross-secE ion t o r
es i s t su r cha rge l oads , ove rbu rdenpressures and lateral
ground pressures togetherwl th any loads f ron surface structures
founded ontop o f t he d r l f t . Sec t i on C -C o f F i gu re
6indlcates that Ehe s ide wal ls of the fan dr i f t havebeen
deslgned as deep beams over Ehe sDan becweenEhe shaf t and cencral
p l le cap to acconmodaEe heavyfounda t l on l oads f r on su r f
ace s t r uc l u res .
ConsEruct ion sequences should be taken account ofl n des lgn .
The ab l l i t y o f t he d r i fE t o ac t as aEhree 6pan beam ln
l ts f inal condi t ion nay need to
r { i t h f an d r i f t en t r y
be augroented by an lnvest lgat lon lnto the part lycons t ruc
ted s ta te o f a s i ng le span w i t h acan tL l eve r sec t l on
ove r t he cenEra l p i l e cap . Thela t t e r cond l t Lon i s o
f pa r t l cu l a r impo r tance i n Ehecase of a shaf t sunk in f
rozen ground. ConnecElonof the dr l f t Eo the shaf t should only
be made afcerDost of the ground set t lement dur lng thawlng
hastaken place.
Air and fan dr i f ts are noE fu l ly undergroundstructures ln
the t rue sense, but they are ofpart lcular importance ln that Ehey
forrn anlncerface bel l reen the underground and Ehe surface
V iew down se lby w i s to r . / No . 2 ( upcas t ) sha f t co l
l a r and f o resha f t s t r uc tu reE o t h e r i g h t .
2' 930
S E C T I O N A . A
' ouJ ld Led
I
I
lIl
i
t st'ofi
I
II
IAS E C T I O N B - B
IAS E C T I O N C - C
F lgu re 6 . F a n d r l f E , S e l b y R l c a l 1 N o . 2 ( u
p c a s t ) s h a f t .
-
works . As such , t hey a re no t s l np le Eo cons t ruc t
,requir lng the correct tenporary works approach,conbinlng both c
iv i l englneer ing and rn ln ingtechn lques . Connec t l on t o r
he sha f t t akes p l ace a ta po ln t whe re g round s tab l l i t
y l s poo r and g roundwater lngress lnto Ehe excavat lon is l
lkely. Henceevery atEeDpt should be nade ln the deslgn tos i np l i
f y t he sha fE rouCh ing deEa i l and t o p rov l dethe su r f ace
wo rks s t r uc tu res w l t h f ounda t i onsindependen t o f t he
a i r and f an d r i . f t s .
2 . 5 I n s e t s
Havlng sunk and l - ined a vert lcal shaf t l t isnecessary to
dr lve away hor lzontal ly f ron thebo t t on . The s t r uc tu re
wh i ch l s cons t ruc ted a ! t hep l t bo t t on t haE enab les t
h i s wo rk t o p roceed l s t helnse t ( see F lgu re 7 ) . F i gu
re 8 i s a v l ew o f are l n fo r ced conc re te l nse t unde r
cons t ruc t l on . Thefunct lons of rhe lnset ln a worklng mine
are top rov i de sk l p l oad tng f ac l l i t i e s f o r p roduc
t i onw lnd ing and t r ans fe r l nsca l l a t i ons f o r oen
andna te r i a l s . I c a l so p l ays an l npo r t an t pa r t l
n t hen ine ven t i l a t i on scheee .
Des lgn p r l nc l p l es f o r l nse t s encon rpass two d l s
t i nc tapp roaches as t r ans fe r f r on t he ve r t i ca l d i r
ec t l onto t he ho r i zon ta l i s acconp l l shed . Sha f t I l
n l ngdeslgn nornal ly involves a uni forn loading aroundthe c i r
cun fe rence , ac t i ng l n a r ad ia l d i r ecE ion ,wh i ch c
rea tes a co rnp ress i ve s t r ess w l t hou t bend lngon a c l r
cu l a r shape . W i t h a t unne l , depend ing uponthe overburden
pressure and the deformat ioncha rec te r i s t l c s o f t he rock
, l a t e ra l p ressu res naybe d i f f e ren t f r on t he ve rE
i ca l ones and bend ingloomenEs and shear forces are lnduced in a
c l rcularp ro f l l e unde r Ehese c i r cumscances . I n f ac t ,
f o rthe rectangular and haunched arch prof i les shown inFigure 7,
bendlng moments and shear forces arepresen! whether the loading ls
uni forn al l round orno t . Howeve r , Ehe i r nagn lEudes cou ld
changedepending upon lhe rat io bet \ reen the vert lcal andla te
ra l p ressu res . Desp i t e t h i s p rob len , p rov l ded
both the shaf t neck r lng and the hor izontal roadwaysec t i
ons a re des lgned l n acco rdance n l ! h t he l r ownp r i nc l p
l es , t hen f r on expe r l ence l -E wou ld appea rthat the
lnterconnecl ion between the two Eakes careo f i t s e l f .
One o f t he nos t d l f f l cu l t aspec t s o f l nse t des
ignl s t o de te ro l ne accu ra te l y wha t t he t r ue l oad
ingshould be. In nany cases ru le of thunb nethodshave been
enployed, based on local knowledge andscapda rd p rac t l ce i n pa
r l l cu l a r n l n l ng a rees .F i g u r e s o f ^ 1 3 . 4 , 2 6
. 7 a n d , 5 3 . 5 k N / n 2 ( L / 8 , I l 4 a n dl / 2 t on / f .
t z r espec t i ve l y ) we re t he no rn un t l lr ecen t l y when
t he va lues have r i sen Eo 106 .9 t o2 1 3 . 8 k N / n 2 ( l t o
2 t o n s / f t 2 ) . A p p l l c a t i o n o f t h l sl oad ing
has t ended t o be on a un l f o rn l y d i s t r i bu tedbas l s a
I1 r ound , a l t hough i n sone l ns taccps va lueso f 106 .9 kN
/nz ( I t o r . / fEz ) have been t aken on t heroo f w i t h 53 .5
kN /n2 (L /2 t o t / f t 2 ) app l i ed ro r heve r t i ca l s i
des . No appa ren t l og i c acconpan les t h l sme thod o f l oad
de te rm lna t i on excep t Eha t l f t hesame i n tens l t y o f l
oad ing has been enp loyed t odes ign ano the r s t r uc tu re o f
t h i s t ype i n a s l . o l l a rm in i ng a rea e r l t hou t de
t r i nenEa l e f f ec t s , t heconc lus l on has been t ha t i t
nus t be sa t i s f ac t . o r y .Gene ra l l y t h i s p r i nc i
p l e ho lds t r ue l f l he g roundis conpetent but in a ru le of
thunb approach thet rue f ac to r o f sa fe t y l n t he des ign
rena insunknovn . Whe re t he g round i s l nconpe ten t , hoseve r
, .t he chances o f s t r uc tu ra l f a l l u re becone ve rv r ea
lwhen us l ng t h l s me thod .
F o r g o o d d e s i g n , t h e r e f o r e , 1 t l s i n p e
r a t l v e t ohave a mo re reaL i s t i c app roach t o t he eva
lua t i on o ft h e i n s e t l o a d i n g . I n t h i s r e s p e
c t , p a r t l c u l a r l yw i t h t he s iE ing o f s t r uc tu
res i n coa l neasu ress t ra ta , t he wo rk ca r r i ed ou t by t
he NCB M in lngResea rch and Deve lopmen t EsEab l l shnen t . a t
B recby l nE n g l a n d h a s b e e n h e l p f u l 3 . U s t n g
[ . l l l s o n ' s m e t i o do f des ign , t he c l osu re o f an
unde rg round d r l vage i nweak rock can be re l a ted co t he l i
n l ng s t r eng th andthe rock propert ies obtained f rorn
laboratorytes t s . I n t h i s way , a l l n l ng can be p rov l
ded wh l ch
v
A
Pockets for steeI beons
SECTni B.B
F i g u r e 7 .
I O
S h a f t b o E t o n i n s e t , S e l b y h r i s t o w N o .
2 ( u p c a s t ) s h a f t .
-
ls conpat ib le wi .ch the surrounding strata, and s i tha knorm
factor of aafety. I t should be noted,however, that s i t lng of an
lnseE relat lve to thecoal seam ls of partLcular lnportance
andpreference should be glven to locaELons above andbelos the sof
ter rocks assoclated wi th rhe mLneralbody .
once the t rue lnset loading ls establ ished, i t ls arelat
ively s inple nat ter to determlne the bendlngnonent6 and shear
forces for typical cro6s-sect lonssuch as SecElons A-A and B-B
shoun ln Figure 7.The use of a conputer, for which
standardstructural engineer ing prograns are avai lable,nakes Ehe
analysls easler . In the analysls of thesEructurer account musE be
taken of Ehe resistanceto def lexion of the surrounding rock. The
correctdefornat lon propertLes of the ground need to beintroduced
into Ehe program as spr lng sci f fnesses,as the surrounding rock
rnodl f ies the bendingmonents and shear forces that r rould occur
l f EhestrucEure were to be considered as unconf ined.
2.6 Tunne ls
Baslc pr incip les for tunnel l in ing design have beentouched
on br ief ly in the previous sect ion oninseEs . Th i s i s no t su
rp r i s i ng as t he ho r l zonEa lsect ion of an lnset ls s inply
a Eunnel . The addedconp l i ca t l on i n Ehe case o f t he i nse
t l s t hei nEe rconnec t i on w l t h t he sha f t . As w i t h
Ehe i nse t ,t he ' sec re t t o f good t unne l l i n l ng des ign
i s t oprovide a system shich is conpat ib le wiEh thesurrounding
ground. This means natching up thedefornat lon characEer lst ics of
the ground and thel i n i ng .
To fu l ! ,y understand Ehe role of concrete in tunnell l n i ng
des ign , i t i s necessa ry t o be f an i l l a r w l t htunnel
deslgn and construct ion techniques ingeneral . L in ing
requlrements for tunnels varyimmensely depending upon the ground
condi t ions.Tunnels in hard rock nay be conpletely unsupporEed
e r i t h no add l t i ona l ' cosmeE lc r l l n l ng . I n o
the rt ypes o f s t r aBa , r ock bo l t l ng uay be su f f i c l
en t t oprovide permanent scabl l i ty to Ehe excavat lon rr l -
ththe posslb le use of nesh and sprayed concrete 10more f r iable
zones to prevent f ragnents f romfa l l i ng o f f o r su r f ace
weaEhe r l ng .
For weaker ground condl t lons, pernanent support naybe achleved
using arches, beams and columns orcomp le te r i ngs , a l l f ab r
l ca ted f r on s tanda rd 6 tee lsec t i ons . .A l t e rna t i ve
l y sphe ro lda l g raph iEe , cas tst .eel segments or precast
concrece segnenEs provldea convenienE form of c i rcular Eunnel
construct ion,part lcular ly ln sofE ground condl t lons c lose -
to theaurface. Cast steel segnenEs would noroal ly beenployed as
the f ln lshed l in lng because of theirh lgh load carry lng capaci
ty, but the othersteelwork support sysEer ls and the precast
concretesegnents nay also be used as temporary works pr lorto l in
ing ln concrete on a more pentranenE basis.Flgure 9 shows a typlcal
sof t ground cunnelconstrucElon ln which precast concreCe uni ts
wereinstal led as temporary support pr lor to l in ing wlrhln s lEu
concrete. Flgure 10 ls a photograph takenlnside one of the
tunnels.
As for lnsets, accuraCe deEernlnat ion of thelnposed loadlng ls
of fundanental lnportance ln thedeslgn of tunnel l ln lngs. Hany
soi l and rocknechanlcs theor les are aval lable Eo
deterninepressures on tunnels ln var ious groundcond l t i ons
q . Two bas l c t ypes o f l oad ing
predoninate. One consists of a t r iangular shapedzone of roof
st rata whlch is consldered Co breakaway under graviEy to Lnpose
loading on thesupport lng structure. This could occur insE ra t l f
Led rock o f a conpe ten t naEu re w i t h no s i deo r f l oo r l
oad ing p resen t . The second p r l nc l p l e ,used in neaker
ground, considers a y ie ld zone toexlst around the opening J. This
occurs becauseEhe strengEh of the rock is lncapable ofwichsEandlng
the high local lsed sBresses r , rh ich arecreated around the per
lneter once the excavat ionhas Eaken p Iace . I n i t i a l y i e l
d i ng f l : r s t r akes
F igu re 8 . W isEow No . 1 ( downcas t ) sha f t boE to rn i
nse t unde r cons t rucE ion .
1 1
-
aurtr NlaxSIru6Uft\
ntlfi rilY- - -
l","a" r*^r*ttlsrtxcl
ruraoE$^f IS
I @cRur66 oar ar tr
.?00 lgrc GRO LEYL .O 5 ' APruX
@ f oiooi cuY
MffiTO IE'Ps-tur|e 2
LO^IGITUOINAL SCTION OF TUNNLS (2TSI
Eol t0 PRc^5rcoNcREr *GXrrs
TYPICAL CRoSS SECl loN 0F TUNNELS 12Nol
J IELS tEVt V4t fS Fe@ - t l @ b ' ( !- --$if .-
-\a'
F lgu re 9 . So f t g round t unne l cons t . r uc t i on ; one
o f two coo l l ng wa te r l n t ake t unne l s a t G ra in Po l r
e r S taE lon .
place at the excavatLon face and graduel ly spreadsfur ther lnto
the grouod unt l l s tabl l l ty is onceagaln restored. The opening
ls thereforeconpletely r lnged by a part ly crushed (y le ld)
zone.
In both these approachee, the tLme since excavat ionand the
dlstance f ron the excavat lon face arecr lc lcal . An unsupported
roof , shlch is coopetencshen excavated, nay becone unstable wi th
c ioe asdefornat lon takes place and larger gravi ty forcesare
brought lnCo play ln conJunct lon wiCh theLncreased t r langular
loadlng. Closure of an
excavat l -on, shlch ls restra l .ned at the dr lvageface,
Lncreases t l th d istance back f ron the face upto approxlnately f
lve to s ix d ianeters shen at chisposl t lon l t ls Eost ly
conplete 3. Sone rocks,however, such as salr , exhlb i t t loe
dependentmoveEents whlch nay contLnue throughout the tunnel1 1 f e
.
Based on the prevlous commencs, lE can be seld thacthe ra r t '
o f t unne l l l ng cons i scs o f i ns ta l l l ng t hemost
su{table (safe, econooLcal and serv iceable)l ln lng at exact ly
the r lghc t loe ln phase wi th Ehe
F igu re 10 . The i ns i de o f t he Gra in Power ScaE lon coo l
i ng wa te r i n t ake t unne l s .
t 2
-
\ \ v , < \ \ v 7 , \ \ v / - \ \ v ? , < \ \ v , 7 < \
\ v 7 l < \ \
i t I I I t I I I I I I I
L I N I N 6
S E C T I O N B - 8
--/ |- |
( )
tI[ \
C A S T B A S A L T T I L E
7 315 D iokn r t c r
l,"n .n,,.
III
I
- , - -
i
F lgu re l l . Typ l ca l 1000 t onne sp i r a l chuEe bunke r
sha f t .
-
proceedlng excavat lon. The bul l .d up of load for atr langular
rgof zone approach ls a progressive onedue to the gradual loosenLng
of the rock ln theroo f dependen t upon t iDe . Res t r l c t i on
o f r oo fde fo roa t l on by l nned la te l ns ta l l a t l on o f
t he l i n i ngprevents the zone of inf luence f ron spreadlng
andnLnlnizes gravl ty forces. In the caae of a y le ldzone,
lmmedlate lnsta l lat lon of support c lose tothe dr lvage face
could be achleved but lEs requlred6trength sould be excessive.
InsEal lat lon of thel ln lng at some dlstance back f roo the face
needsless support a6 part of the c losure has al readytaken p1ace.
Provlded the ground renalns cotopetent(ee l f s t and lng ) , t hen
t he re -adJus ted s t r esses w l11be carr ied by the 8l rata or
wl th the asslstance ofnin lnal tenporary support pr lor to l in
ing wl th ath ln skln of st ructural concrete.
The technlque of a l lowlng the rock l tsel f to carryae much of
che poat excavat lon atress as posslb le,ln conJunct lon s l th a n
in lnal l ln lng, nay becons ide red t o be ano the r r sec re t r
o f good t unne ldeslgn. The Nev Auscr lan Tunnel Method (NATM)
5
deEonstrates th ls aspecB to the fu l l and enploysonly rock bol
ts, nesh and a th ln skin of sprayedconcrete as Che pr luary
support sysCeo whichasslsts the ground to carry the load.
Ic ls l r l th in th ls context that concrete ls used lntunnel
construcClon. The ground condi t lons and i tsde fo rna t l on cha
rac te r l s t i c s subsequen t Eo excava t l onnust be knorn
before l in ing concepts can be fu l lyfornulated. Pre-knowledge of
ground condlc ions lsobEalned f ron geological .and hydrogeologlcal
boreholedata. The NATM goes even fur ther ln l ts lnpl lc l tre l
lance on lnstrunentat ion and ln sLcu observat lonsas tunnel
construct lon proceeds. These observat lonsare used not only to
checkr 'on the perfornance andsa fecy o f t he t unne l bu t t o '
gu lde t he p rov l s i on o fseconda ry o r t e r t l a r y supPo
r t .
Ic can be seen that . the possib le range of concreteusage for
tunnel construct ion ls therefore wide andenbraces the fu l l range
of sprayed, precast and insLtu work. The use of sprayed concrete
isnldespread underground and nany references areava l l ab l e e l
sewhe re conce rn lng iEs use .
2.7 Sp i ra l chu te bunker shaf ts
The concrete structures discussed so far have al1been related to
verBlcal shafEs or hor izontaltunnel dr lvage. We now coDe to var
lous structureswh l ch a re consCruc ted t o f u l f l l spec i f l
c f unc t l onsconnected wl th working olne operat lons.
In a mlne, handl ing facl l l t ies underground are ofexEreme
lmportance for t ransport lng the exlracted
nater la l - to the surface. Coal is nornal lyt ransporced
underground f roB extract ion face to theho l sc l ng sha f t , o r
a l t e rna t l ve l y t o t he su r f ace upan l nc l l ned d r l
f t , us i ng conveyo rs . The cu r ren tt rend ln coal Elnes ln
the Uni ted Kingdom,
fol lowing thelr or ig inal developrnent ln Gernany, L6to use
splra l chute bunker shaf ts (see Flgure 11)lo l ine on the
conveyor sysEen. These provldestorage facl l l t ies underground ln
addl t lon to belnga means of regulat ing coal f lov. Coal is fed
lntothe in let chute, s l tuated ln che bunker topchauber, and f
lows downwards splra1ly ln the chutese t i n t o t he va l1 . The
pu rpose o f t he sp l r a l , asopposed t o a f r ee f a l 1 sys
ten , l s t o con t ro l t heinf low of coal so that degradaclon
and the r iak oflncendive sparklng are reduced and wear on theshaft
r ra l ls and dust are miniu ized. Rernoval of coalis through Ehe
conical out let in the bot tdu chanberroof , feedlng back onto the
naln 1 lne conveyortransportat lon systen. The bunker shaf t shown
lnF lgu re 1 l l s cons t rucEed f r om re l n fo r ced conc re te
,c a s t i n s i t u .
At the present t lne, splra l chute bunker shaf ts arecons t ruc
red w l t h a d l ane te r o f 7 . 315 n ( 24 fC ) andnlEh a helght
nornal ly of about 40 o Eo glve acapacl ty shen fu l l of 1000
tonnes.
Construct lon of spira l chute bunker shaf ts can Eakeseveral
forns. They nay be instal led uslng snal lp recas t conc re te b l
ocks (Thyssen sys teo ) o r l a rge r ,bo lEed , p recas t conc re
te sha f t l i n l ng segnen ts(Cenentat lon l , t ln lng/Buchan
systetr) . In both cases,spec ia l un i t . s a re r equ l r ed f o
r t he sp l r a l ( seeF igu re 12 ) . Vo id f i l l i ng beh lnd t
hese un l t s du r l nglns ta l l a t l on i s ca r r i ed ou t us
l ng a g rou t l ngp rocess . A l t e rna t l ve l y , i n s l t u
conc re te can beused w i t h o r w l t hou t g l ass f l . b re r
e l n fo r cedconcrete panels as permanen! fornwork. In a l lt hese
f o ros o f cons t ruc t i on , cas t basa l t t 1 l esp rov lde t
he wea r i ng su r f ace f o r t he sp l r a l p ro f l l e( s e e
F l g u r e 1 l ) .
Des lgn p r l nc i p l es f o r t he i n f eed chu te t o t
hebunke r t op , t he sp i r a l l t se l f and t he ou t f eedsys
ten , a re ou t l l ned by voss 5 , I n t he s t r uc tu ra ldes
lgn o f t he sha f t , t he ques t i on o f l oad ing i sf o renos
t : two k i nds requ i r e sc ru t l ny . F l r s t , t hecon ta i
ned ma te r i a l imposes s i l o - t ype , l a t e ra lp ressu res
and ve r t i ca l shea r f o r ces on Che wa l l .Second , t he
poss ib l l l t y o f ex te rna l g round l oad ingmus t be cons
ide red . Howeve r , i n nos t cases ,bunker shaf ts are s i tuated
ln cotrpeEent ground andw l l l on l y be sub jecced t o ex te rna
l g round p ressu rest f f u r t he r ad jacen t deve lopmen t d r
i vage i s ca r r l edou t subsequen t l y . I f t h i s occu rs ,
g round novenen tscou ld be l a rge , v i r t ua l l y i nposs ib l
e t o de f l neaccu raee l y and canno t be accomuoda ted l n des
lgn .
F lgu re 12 . Ceu ren taE ion M in i ng /Buchan bo l t ed , p
recas t conc re te , sp l r a l chu te bunke r sha fE segnenE .
L 4
-
I n conpe ten t g round , t he l oad o f Che coa l con ta l
nedln t he bunke r can be t r ans fe r red d i r ec t l y f r om
thel i n i ng t o t he su r round ing g round by mechan i ca li n t
e r l ock . La te ra l p ressu res a re r es i s t ed d i r ec t l
yby t he rock , and ve r t l ca l shea r f o r ces byfr lc t lonal
reslstance and nechanical inter lock.Lia lngs of bol ted precast
concrete segments, lns l tu concrete or f lbre re inforced concrete
panelt l ipes therefore need only be designed nonlnal lyfor st
rength as the internal loadl-ng is d lss lpated
dlrect ly into the ground. Thls leaves the baee s laband bot ton
chanber structure to carry the ef fect lveve r t l ca l s i l o p
ressu re aC t ha t l eve l . The sp i r a lchuce also servea to
lmprove the interact ion betweenthe bunker and the ground, provid
lng an exEernalco rksc rew e f f ec ! . I n f he case o f t he b l
ock l i n i nghowever, in whlch Che elenenEs are noc physlcal
tyconnected together, considerat lon may need to be glvento carry
lng Ehe fu11 welght of the 6haf t l in ing andEhe bunker contentE
on the bot ton charnber structure.
sEcTtott c-c
Floor r lob pruturt rr l i r fond groul ing pip. l
s E c T r 0 N 8 - 8
F igu re 13 . sunp Eank f o r ho ld l ng m ine wa te r p r i o r
t o pump ing Eo su r f ace .
l -5
-
stroro c c$cr :o gror iag cl i l rctr
l lt l
V I E W O N B - B
F lgu re 14 , Unde rg round sa fe t y p l ug and bu l khead doo
r .
2.8 Sump tanks
The con t ro l o f ea te r l s an lmpo rEan t aspec t o foperat
lng an underground nine. Sunp tanks arel nva r l ab l y r equ i r
ed Eo ac t as co l l ec t l ng po in t s f o rwater. Punplng
arrangenents can then be eoployedfo r iEs t r ans fe r t o o the r
pa r t s o f l he D lne o r t ot he su r f ace f o r d i sposa l
.
A typical re inforced concrete sump tank isi l l u s t r a red l
n F l gu re 13 . Th i s Eank has beens l t ua ted i n an a rea whe
re i ng ress o f wace r cou ldoccu r t h rough t he s t r a ta beh
lnd t he s i de wa l l s andbe low t he f l oo r . Hence , a p
ressu re re l l ev i ngsys ten has been l ns ta l l ed . The p
ressu re re l l ev l ngsys ten consLs t s o f a number o f p l pes
l ead ing ou tf rorn below the f loor s lab to prevent bul ld up
ofsE ra ta wa te r p ressu re wh i ch cou ld danage t hes t rucEu
re . These p l pes cou ld a l so be used Eo g rou tup t he i nEe r
face zones f o r sea l l ng pu rposes l f l twe re necessa ry t o f
l l l t he who le a rea conp leEe l yn l t h conc re te due ro
excess wa te r i ng ress .
I n some a reas unde rg round , t he sE ra ta cond l t i onsnay
be suf f lc lent ly conpetent and lnperrneable Eoa l1ow wa te r s t
o rage w i t hou t any add l t l ona ll i n i ng . A t h i n l aye
r o f sp rayed conc re te on s tee lnesh may su f f l ce l n oEhe r
a reas . Howeve r , whe re ano re subs tan t i a l sE ruc tu re l s
r equ l r ed , t he des ignshou ld f o l l ow t he gu lde l l nes o
f Lhe re l evan t Codeo f P r a c t l c e / .
2 . 9 P l u g s
Al l led to the cootro l of eraEer in a mlne is theab l l i t y
! o sea l o f f secE ions aga ins t naJo rl ng ress . P lugs may be
l nc l uded f o r sa fe t y , as m inedeve lop rnen t p roceeds , o
r t hey oay be l ns ta l l ed asan emergency p rocedu re i f a l a
rge l n rush occu rs .The foro of the plug var ies depending upon
thecond l t l ons . I n an ene rgency , a so l l d conc re te p l
ugwould be constructed as a permanent seal ing of ftDeaau re . P
lugs l ns ta l l ed du r l ng an Ln l t l a l n i nedevelopnent
scheme wi l l need to a11ow men,
r6
nater la ls, equlpoent and serv lces to pass throughand a l so
be capab le o f r ap id c l os l ng o f f . Such aplug, lncorporat
lng a bulkhead door, ls shown lnF lgu re 14 .
The p l ug wh i ch i s i l l u s t r a ted has been des igned
onthe bas i s t ha t f u l l hyd ros ta t i c p ressu re cou
ldprevaLl ln the event of a f lood, the naxinun headbelng the depth
f ron Ehe ground surface to thelnsEa l l a t l on l eve l unde rg
round . Th ree na lne lemen ts a re i nco rpo ra ted i n t he p l
ug :
(a ) conc reEe cy l l nd r i ca l p l ug ;(b ) s t ee l l oad t
r ans fe r cy l i nde r ;( c ) s t ee l bu l khead doo r .
The concrete cyl lndr lcal p lug has two purposes. T ' t lef l r
s t i s t o p rov l de a ba r r l e r t o w l t hs tand t he endhyd
ros ta t i c p ressu re . Th i s l s ach leved byp rov ld i ng a su
f f i c i en t l eng th t o keep t he shea r a tthe concrete to
rock lnter face wi th ln pernlssib lel l n l t s . Second l y , t
he p l ug i s des lgned as a oeansof prevent lng the passage of
nater through the plugl t se l f , aE t he conc re te t o r ock l n
t e r f ace and a l soch rough t he sE ra ta . When g rou t l ng t
he con tac t zonebetween Ehe plug and the rock, or grout ing the6 t
ra ta , g rea te r p ressu re t han t he p reva i l i ng headl s r
equ l r ed , t o chase t he wa te r back a l ong i t slnf low
paths. The concrete tube nust therefore becapab le o f w l t hs
tand ing p ressu res marg lna l l y l nexcess o f hyd ros ta ! i c
i n t he rad la l d i r ecE ion .Add lC lona l g rou t sea le he lp
t o c l ose o f f poss ib l el eakage pa ths .
The steel load t ransfer cy l lnder bears onto r lngf langes and
al lons che bulkhead door pressure Eo beca r r l ed by t he conc re
te cy l l nd r l ca l p l ug . Enoughf l enges a re p rov i ded t o
r educe t he bea r i ng s t r essesto pe rn l ss l b l e l l o l t
s . The s tee l bu l khead doo r i sdes lgned t o ca r r y t he f u
l l hyd ros ta t i c p ressu re aoda l so l nco rpo ra tes a man
access t ube . Se rv l ces canbe ca r rLed t h rough s tee l p i
pes e rnbedded i n t heconc re te cy l l nd r l ca l p l ug , g l
ands be lng l ns ta l l eda t bo th ends o f t he p l pes f o r sa
te r sea l i ng .
-
5. Gonstrrrction Method.s3 . 1 I n t r o d u c t i o n
The use of concrete ln underground developrnent workhas t h ree
d l s t l nc t aspec t s . F l r sE , any excava t l onnus t be
secu red be fo re casE lng t he conc re te aga ins tl t . Th i s l
nvo l ves p rov l d i ng t he co r rec t t enpo ra ryuorks support
ln phaee wl th the excavat lonprocedure. Second, fornwork and fa
lsework arerequLred, to ensure thaL the concrete, when
placed,remains ln the desired posi t lon and ls of the
shapeexpected. The th l rd aspect of concreteconstruct ion ls the
abl l l ty to roove the fornworkand fa lsework safely and quickly
for subsequentpou rs .
I n Ehe f o l l ow ing secE lon6 , t hese aspec t s a reconsLde
red w i t h r e fe rence t o t he pa r t l cu l a rs t r uc l u res
p rev l ous l y desc r l bed . Subsequen tsecELons cover batchlng
planc and t ransportat lonand p l ac i ng t echn lques .
3.2 Co l la rs and fo reshaf ts
Figure 15 i l lustrates lhe method employed tocons t ruc t t he
co l l a r and f o resha fE o f a f r ozensha f t and F lgu re 16 l
s a v l ew l ook ing i ns l de a t t heteopo ra ry suppo r t p rov
l ded f o r such a sc ruc tu re ,p r l o r t o l i n i ng l n conc
re te . Th t enpo ra ry suppo r t
f o r t he excava t l on cons i s t s o f s t ee l l l ne r p l
a tes
and s tee l r l ngs , t he l a t t e r be ing f ab r l ca ted f
r ons tanda rd sec t i ons . Th l s l ype o f t eEpo ra ry suppo r
twould normal ly be used through the sof t , sur faceso i l depos l
t s un t l l bed rock i s r eached . On f u r rhe rs lnklng ln
competent ground, only rock bol ts andmesh need to be used for
tenporary support .
I n f r ozen g round , t he s t r engEh o f t he so f t su r f
aceso l l depos i t s Ls enhanced t o such an ex tenc t ha t l
trenalns competen! when excavated. The 1lner p lafesand r i ngs a
re p rov i ded , t he re fo re , as an add l t i ona lsafety
neasure and also to prevent squeeze on thef resh l y cas t conc re
te l l n l ng as a r esu l t o f t hdw lngln t he g round caused by
hea t o f hyd ra t l ondevelopnent. However, care nust be Eaken to
ensuretha t t he i ce wa1 l i s conp le te l y c l osed a round i t
spe r i ne te r , be l ow t he f r eeze ce l l a r , i n o rde r
Eoprevent Lngress of ground water Lnto theexcava t l on .
Where the ground f reezlng nethod i .s noE used,conslderat lon
oust be given to provid ing teuporarysupporE which can sustain the
inposed groundp ressu res . A dewa te r i ng scheme cou ld a l so
beneeded .
The l ln lng forowork and oeans of handl ing theconc re te i n t
he co l l a r and f o resha f t a re s i n i l a r t ot he equ i va
len t i t ens l n s t anda rd sha fE s l nk l ngp rac t l ce . They
a re de ta i l ed l a t e r i n Sec t i on 3 .4 .
T l p D l n g
F o p o
8 r n k t r n a n a
V . n t l l . t l o n C r b i n
F r n
A c c a r l
L a d a t a r i a y
H o p p i t
T o n p o r r r y S u p p o r t
l l n e l
T a m p o r a r y S r t t o r t
P l r t . !
T r r c l l o u n t a d
! . c k h o .
T Y P I C A L F O R E S H A F T
c o x s T R U c T t o x
F igu re 15 . Co l - l a r and f o resha fE excava t i on and t
enpo ra ry suppo r t .
L 7
-
F igu re 16 . W is tow No . 2 ( upcas t ) sha f t co l l a r
and
3 . 3 A i r a n d f a n d r i f t s
Provld ing a tenporary works schene for a i r and fand r l f t s
has i t s own pa r t l cu l a r p rob lens . AsDen t l oned l n Sec
t i on 2 .4 , connec t l on t o t he sha f t
Eakes place at the most vulnerable polnt for groundstabl l l ty
and ground nater ingress lnto theexcavaElon. At th is point , the
tenporary worksscheme for the shaf t construcl lon must be
Eatchedup l r i t h t ha t f o r t he d r l f t . I n add i t i on
, i n f r ozenground, the f reeze cel lar muat be supported aboveth
i s pos l t l on r h i l e excava t i on p roceeds be lov ( seeF l
g u r e I 7 ) .
In conjunct lon s l th a f tozen shaf t , a f rozen
groundtenporary works support systen for the dr l f t can bep rov
lded . Howeve r , t h l s i s suscep t l b l e t o seve reground
novements ln the forru of heave dur lngfreezlng and seEt lenent ln
the thasing per lod.Provided the ground condl t ions are sul table,
theau lho r r s p re fe r red DeEhod o f t enpo ra ry wo rks Ls t
hefo l l ov i ng .
( l ) P rov i de scee l shee t p l l es f o r t he d r l f t r i
gh tthrough to the proposed shaf t col lar excavat ionpe r i ne te
r , p r i o r t o l ns ta l l i ng t he sha f t f r eezetube d r i
l 1 pad and t he f r eeze ce l l a r .
( 2 ) Du r l ng t he f r eeze ce l l a r cons t ruc t i on t
excava tebe low t he f l oo r s l ab t o p rov l de re i n fo r
cedconc re te co rbe l s wh l ch cou ld I a te r become anin teg ra
l pa r t o f t he sha f t , r e i n fo r ced conc re teco l l a r s
t r ucEu re . Ca re shou ld be t aken no t t oexcava te deepe r
chan t he t op l eve l o f t he p roposedd r l f t r oo f s l ab .
P rov i de enough co rbe l s ! o ca r r yt he we igh t o f t he
secE lon o f f r eeze ce l l a rspann lng ac ross t he d r i f t .
P rov i de re l n fo r cemen ta t t he rea r o f Che co rbe l f o r
bend ing ou twa rds ,on exposu re du r l ng t he sha f t excava t l
on , t o p rov l dethe necessa ry t l e l n w l t h t he sha f t co
l l a r . Thef reeze ce l l a r s t r uccu re l t se l f , shou ld
be are l n fo r ced conc re te s t r ucEu re capab le o f be lngca
r r i ed by t he co rbe l s ove r t he w idEh o f t hed r i f t
excava t l on .
l 8
f o resha f c unde r cons t ruc t i on .
P rov id i ng shee t p l l es r l gh t t h rough t o che sha f
twa l l ensu res t ha t t he g round 1s co rop l - e te l y secu
reda t Eh i s pos i r i on , wh i l e t he f r eeze ce l . l a r l
ssuppo r ted f r om the co l l a r s t r uc tu re . Whe re g
roundwa te r l s p resen t , a we l l dewa te r i ng sys l em oay
berequ i r ed .
I n Sec t i on 2 ,4 , IE was reconmended t ha t connec t l ono f
t he d r l f t t o t he sha f t shou ld no t occu r , i n t hecase
o f a f r ozen sha f t , un t l l t haw lng se tE lenen t l sconp
le te . P rov i s l on nus t be oade , t he re fo re ,du r i ng
cons t ruc t l on f o r t h l s t o be accommoda ted .G a p s , w l
E h o r n l t h o u t c o n t l n u i t y o f r e l n f o r c e r u
e n t ,ous t be a l l owed i n t he f l oo r , wa l l s and roo f f
o rt h i s pu rpose . Whe re t he re i n fo r cenen t i s n i n lma
l ,a 300 nu r gap w i t h con t i nu i t y wou ld p robab l ysuf f
lce. For an abundance of re lnforceuent ln thedeep bean s ide wal
ls of the box cross-sect lon dr l f t(see Sect lon C-C tn Figure 6)
, rehich provldes anuch stLf fer e leoent of realstance to bendlng,
awlder gap preferably of at least a required lapl eng th , shou ld
be a l l owed w i t h d l scon l l nu l t y o f t hesteel . The
detai l r [ust a lso be watert ight andrequlres a steel seal lng
plaEe across the back ofthe gap. Fron Ehe posl t ioning poln! of
vLes, thebest locat lon is away f ron the shaf t towarde checen t
re p l l e cap .
Propr ietary formwork systens can be eoployed fort he cons t ruc
t l on o f a l r and f an d r l f t , s w l t h t r eg t l esfo r r
oo f so f f l t suppo r t . Conc reE ing p roce< lu res a res i
n l l a r t o t hose used i n su r f ace wo rks .
3 . 4 S h a f t l l n l n g
F lgu re 17 l l l u s t r a tes t he bas i c e l enen t s l nvo
l vedln t he l i n i ng o f sha f t s . L i n i ng 16 ca r r i ed
ou tdownwards, as s inkLng proceeds. The face of theexcavatLon ls
only advanced as far ahead of thel ln lng as the ground condlElons
al low, the s ldesbelng secured by rock bol ts and nesh. In
wetcondl t lons backsheet.s of PVC, fastened to the rockbo l t s
and oesh f o r cas t l ng t he conc reEe aga lns t ,are used to
channel the wacer behind, out f low belng
-
Sink ingheodf rome
Muckingsystem
Brine rnqinFree ze ce l tor
4 Orumcopston winch
Vent i lo t ionDouble drum
w i nderAirond
dr i f tshqft cot lqr
Freeze tubes
Scrv i ce s
Honging rodsfor formwork
Pumpingryr t rm
Mutt i -deck scof fotd
Muc k inguni t
Stondqrd formwork
Muck hoppi t Cqctus grob
Figure 17. Coumencement of shaf t s inklng and l ln lng.
t 9
-
V c n t i l a t i o n
R i r i n g M r i n
B l a t t i n g B o r
C o n c r r t c
D i r t r i b u t i o n
D e r h P o l
P r o t r c t i v r
C a n o p y
S t c a d y C h e i n r
G u i d c R o l l r r r
S h u t t r r i n g S h u t t r r i n gW i n c h r t
S w i t c h g r r r &
L i g h t i n g
T r r n s f o r r n r r r
S i g n i I C a b l c
H r n g i n g R o d r
C o m m u n i c e t i o n
C r b l r
C o n c r c t i n g
Pipr Boo t - \ - -
W r t o r T a n k
T o o I 8 o r
S t e g c L i g h t i n g
S t r g r W e t e r
P u m p
S t c a d y
J a c k sV c n l i l a t i o n
O p c n i n g C o v c r
S i n k i n g L i g h t r T o o l B o x
D r i v c r c C a b R o t a r y A r m
M u c k i n g
U n i tC a c t u g G r a b
H o p p i t s
S u m p
P u m p
F i g u r e 1 8 .
20
Sca f f o l d used f o r sha f t s l nk i ng and l l n i ng
.
-
conc ro l l ed v l a p i pes t o t he g rou t po r t s l n t
hefornwork for punping to the surface dlsposalp o l n t s .
A11 s lnking, l ln lng and fornwork handl lngope ra t l ons l n
a sha f t a re ca r r i ed ou t f r om a nu l t l -deck sca f f o l
d suspended f r on t he head f rane ( seeF tgu re 17 ) . A caps t .
an w inch ra l ses and l owe rg Eheecaffo ld. Flgure 18 shows the
general arrangeoento f a t yp l ca l s ca f f o l d and F lgu re 19
l s a v i ew o f afou r deck sca f f o l d be lng i ns ta l l ed l
n a sha f t . .
Sha f t l i n l ng f o rmso rk ( see F lgu re 20 ) i s suppo r
ted ,dur ing concrete pour ing, by rneans of hanglng rodssuspended
f ron the l l f t above. The kerb r ing, oncei t l s l l ned and l
eve l l ed , ac t s as a scop -end co t heboE ton o f t he l l f t
be l ng consEruc ted and p rov l dea a
seat lng upon whlch to lo i rer the complete eet offormwork r
lngs f ron the prevloue pour. Thelower lng of the forosork ls
achLeved by rneana ofw lnches s l i ua ted on l he sca f f o l d (
see F lgu re 18 ) .
F l gu re 2 l i l l u s t r a te6 t he conc re te l l n l
ngsequence. Pour doors in the fonnwork asslst lJ l ththe placlng of
the concrete and the specla l shaped
Jo ln t ( see F igu re 20 ) pe rn lEs na t ch lng up t o t
heprevlous pour. The concrete 1s t ran6ported f ronthe su r f ace ,
v i a a ve r t l ca l p l pe l l ne l n t he eha f t ,and l s r ece
i ved f i r s t by a dash po t and t hen by ad l s t r l bu t l on
box ( see F tgu re 21 ) . Passage i n t o t he
fornwork ls by oeans of f lex ib le hoses at tached toe tee l p
tpe ou t l e t s f r om the d l s t r l bu t i on box .} { e thods
o f conc re te d i s t r i bu t l on a re d l scussed no ref u l 1
y l a t e r l n S e c t l o n 3 . 1 0 .
F i g u r e 1 9 . W l s E o w N o . 2 ( u p c a s E ) s h a f t
f o u r - d e c k s i n k i n g s c a f f o l d b e i n g i n s t a
l l e d .
2 l
-
P r o v l o u r l y C o n c r c t r dL .ng th
G r o u t r r R l n g
H r n g l n g R o d R txosH
I r t c h . r R l n g
S t r n d r r d R l n g r
R o c k S o l t r G r o u t l n g P o r t r
W l r o I o r h Conc r r t r Pou r Doo r rP r n r l r
D
H r n g I n g R o d r S t e n d r r d R l n g r
t c r l b l n glo r rd r
H r n g I n g R o d l l u t r K r r b R l n g
Figure 20 .
2 2
Sha f t f o rnwo rk r i ngs .
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