Tunnel Design Guidelines Paper

8/20/2019 Tunnel Design Guidelines Paper

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F E AT U R E R E P O R T

G u i d e lin e s f o r th e D e s i g n o f Tu n n e l s

ITA Work ing G ro u p on G e ne ra l Approac hes t o th e Des ig n o f Tunne l s

A b s t r a c t - - T h i s s e c o n d r e p or t by t h e I TA Wo r k i n g G r o u p o n G e n e r alA p p r o a c h e s t o t h e D e s i g n o f Tu n n e l s p r e s e n t s i n t e r n a t i o n a l d e s i g np r o c e d u r e s [ o r t u n n e l s . I n m o s t t u n n e l l i n g p r o j e ct s , t h e g r o u n da c t i v e ly p a r t i c i p a t e s i n p r o v i d i n g s t a b i l i ty t o t h e o p e n i n g . T h e r e f o r e ,t h e g e n e r a l a p p r o a c h t o t h e d e s i g n o [ t u n n e l s i n c l u d e s s i tei n v e s t i g a t i o n s , g r o u n d p r o b i n g s a n din-s i tum o n i t o r i n g , a s w e l l a sthe ana lys is o f s tresses and de[ orma t ions . For the la t te r, the d i ffe rents t r u c t u r a l d e s i g n m o d e l s a p p l i e d a t p r e s e n t - - i n c l u d i n g t h eo b s e r v a t i o n a l m e t h o d - - a r e p r e s e n t e d. G u i d e l i n e s [ o r th e s t r u c tu r a ld e t a i l i n g o f t h e t u n n e l l i n i n g a n d n a t i o n a l r e c o m m e n d a t i o n s o nt u n n e l d e s i g n a r e a l s o g iv e n . I t i s h o p e d t h a t t h e i n f o r m a t i o n h e r e in ,b a s e d o n e x p e r i e n c e s [ r o m a w i d e r a n g e o [ t u n n e U i n g p r o j e c t s, w i l l b e

d i s s e m i n a t e d t o t u n n e l d e s i g n e r s t h r o u g h o u t t h e w o r l d .

R ~ s u m ~ - - L e g r o u p e d e t r av a il A I T E S s u r le d im e n s i o n n e m e n t d e st u n n e l s p r b s e n t e i c i s o n d e u x i b m e r a p p o r t . E n r a s s e m b l a n t t o u t e s le sin[ormat ions , qu i b ta ien t access ib les en t re les pays sur led i m e n s i o n n e m e n t d e s t u n n e l s , n o u s e s p b r o ns , q u e l e s e x p b r i e nc e sg a g n b e s s u r b e a u c o u p d e p r o j e t s d e s t r a v a u x s o u t e r r a i n s s e r o n tp r o p a g b e s d a n s t o u t l e m o n d e . P a r c e q u e l e s o l p a r t i c i p e d ' u n e g r a n d ep a r t i e f i [ o u r n i r d e s m o y e n s d e s t a b i l it b p o u r d e s o u v e r t u r e ss o u t e r r a i n e s , d e s m b t h o d e s d e d i m e n s i o n n e m e n t c o m p r e n n e n t a u s s ib ien les inves t iga t ions sur le chant ie r, l es essa is labora to i res e t las u r v e i l l a n c e p e n d a n t l e p r o g r b s d u t r a v a il q u e l ' a n a ly s e d e sc o n t r a i n t e s e t d e s d b[ o r m a t i o n s. C o n c e r n a n t c e d e r n i e r p o i n t , d e sm o d b l e s d e d i m e n s i o n n e m e n t d i [ ] b r e n t s e t a c t u e l l e m e n t a p p l i q u b s

sont prbsentbs , y compr is auss i la mbthode d 'observa t ion .R e c o m m e n d a t i o n s p o u r l e s d b t a i ls d e r e v ~ t e m e n t et q u e l q u e sr e c o m m a n d a t i o n s n a t io n a l es s u r l e d i m e n s i o n n e m e n t d e s tu n n e l sachbvent ce rappor t .

1 . Sc o pe o f t he G u i de li n e s

Th e I n t e r n a t i o n a l T u n n e l l i n g A s s o c ia t io n ( I TA )W o r k i n g G r o u p o n G e n e r a l A p p r o a c h e s to t he D e s ig no f Tu n n e l s w a s e s t a b l i s h e d i n 1 97 8. A s it s f i r s t p r o j e c t ,

t h e g r o u p d e v e l o p e d a q u e s t i o n n a i re a i m e d a t c o m p i l i n gi n f o r m a t i o n a b o u t s t r u c t u r a l d e si g n m o d e l s u s e d i n d i ff e r e n tc o u n t r i e s f o r t u n n e l s c o n s t r u c t e d p r i o r t o 1 98 0. A s y n o p s i s o ft h e a n s w e r s t o t h e q u e s t i o n n a i r e w a s p u b l i s h e d b y t h e

I n t e r n a t i o n a l Tu n n e l l i n g A s s o c i a t i o n in 1 98 2 ( I TA 1 98 2) .A s a c o n t i n u a t i o n o f t h a t f ir s t r e p o r t , t h e w o r k i n g g r o u ph e r e i n p r e s e n t s g u i d e l i n e s t h a t a t t e m p t t o c o n d e n s e t h ev a r i o u s a n s w e r s f r o m t h e fi r st r e p o r t a n d i n c l u d e a d d i t i o n a le x p e r i e n c e s i n t h e g e n e r a l a p p r o a c h e s t o t h e d e s i g n o f t u n n e ls t r u c t u r e s. T h e s e g u i d e l i n e s f u l f i ll o n e o f t h e m a i n o b j e c t i v e so f t h e I n t e r n a t i o n a l Tu n n e l l i n g A s s o c i a t io n , n a m e l y, t od i sp e r se i n f o r m a t i o n o n u n d e r g r o u n d u s e a n d u n d e r g r o u n ds t r uc t u r e s t h r o u g h o u t t h e w o r l d b y cr o s s i n g n a t i o n a l b o r d e r sa n d l a n g u a g e b a r r ie r s .

T h o s e i n t e r e st e d i n t h e s u b j e c t of t u n n e l d e s i g n s h o u l d a l s oc o n s u l t p u b l i s h e d r e p o r t s o f o t h e r I TA w o r k i n g g r o u p s , e . g.t h e r e c e n t I TA r e p o r t o n c o n t r a c t u a l s h a r i n g o f ri s k (s eeT & U S T 3 :2 ) a n d I T A r e c o m m e n d a t i o n s o n m a i n t e n a n c e o ft u n n e l s ( s eeT & U S T 2 :3 ). F u r t h e r m o r e , a n u m b e r o f n a t i o n a l

a n d i n t e r n a t i o n a l o r g a n i z a t i o n s , s u c h a s t h e I n t e r n a t i o n a lS o c i e ty o n R o c k M e c h a n i c s , h a v e p u b l i s h e d r e c o m m e n d a -t i o n s o n r e l a t e d s u b j e c t s , s u c h a s f i e ld m e a s u r e m e n t s a n dl a b o r a t o r y t e s t i n g s f o r r o c k a n d g r o u n d . S o m e o f t h e s ep u b l i c a t i o n s a n d r e p o r ts a r e l i st e d in t h e A p p e n d i x .

I n t u n n e l l i n g , m o s t o f t e n t h e g r o u n d a c t iv e l y p a r t i c i p a t e si n p r o v i d i n g s t a b i l i t y t o t h e o p e n i n g . T h e r e f o r e , t h e d e s i g np r o c e d u r e f o r t u n n e ls , a s c o m p a r e d t o a b o v e g r o u n ds t r u c tu r e s , i s m u c h m o r e d e p e n d e n t o n s u c h f a c t o rs as t h e s it es i t u a t i o n , t h e g r o u n d c h a r a c t er i s ti c s , a n d t h e e x c a v a ti o n a n ds u p p o r t m e t h o d s u se d . R e c o m m e n d a t i o n s o n t u n n e l d e si g n

T h i s r e p o r t is e d i t e d b y H e i n z D u d d e c k , A n i m a t e u r o [ t h eI TA Wo r k i n g G r o u p o n G e n e r a l A p p r o a c h e s i n t he D e s i g n o /Tu n n e l s . P r e s e n t a d d re s s : P r o [. H e i n z D u d d e c k , Te c h n i c a lUnivers i ty o / Braun schwe ig , Beethovens t rasse 51 , 3300 Brau nschw eig ,F e d e r a l R e p u b l i c o [ G e r m a n y.

n a t u r a l l y a r e l i m i t e d w i t h r e g a r d t o t h e i r co n s i s te n c y a n da p p l i c a b i l i t y b e c a u s e e ac h t u n n e l l i n g p r o j e c t i s af f e ct e d b ys p e c i a l f e a t u r e s t h a t m u s t b e c o n s i d e r e d i n t h e d e s i g n .N e v e r t h e l e s s , i t i s h o p e d t h a t t h e g e n e r a l o u t l i n e p r o v i d e d i nt h e se g u i d e l i n e s , b as e d o n t h e e x p e r ie n c e g a i n e d f r o m m a n yt u n n e l l i n g p r o j e c ts , m a y b e o f s o m e h e l p f o r t h o se s t a r t i n g ap r o j e c t .

2 . O u t l in e o f G en e r a l Ap pro a ches2 1 G e n e r a l P r o c e d u r e i nD e s i g n i n g a Tu n n e l

P l a n n i n g a t u n n e l l i n g p r o j e c t r e q u i r e s th e i n t e r d e p e n d e n tp a r t i c i p a t i o n o f t h e f o l l o w i n g d i s c i p l in e s , at a m i n i m u m :

• G e o l o g y.• G e o t e c h n i c a l e n g in e e r i n g .• E x c a v a t i o n t e c h n o l o g y, e .g . m a c h i n e t u n n e l l i n g .• D e s i g n o f t h e s u p p o r t i n g s t r u c t u r a l e le m e n t s , i n c l u d i n g

l o n g - t e r m b e h a v i o r o f m a t e r i a l s .• C o n t r a c t p r i n c i p l e s a n d l a w.

A l t h o u g h t h e e x p e r ts i n e a c h o f t h e se d i s c i p l i n e s m a y b er e s p o n s i b l e o n l y f o r t h e i r s p e c i fi c a r ea o f k n o w l e d g e , t h ed e c i s i o n o n t h e m a i n d e s i g n f e a t u r es s h o u l d b e t he o u t c o m e o ft h e c o o p e r a t i v e i n t e g r a t i o n o f a l l t h e d i s c ip l i n e s . O n l y t h u sc a n i t b e e n s u r e d t h a t t h e p r o j e c t , i n a l l i t s d e t a i l s , h a s b e e nd e v e l o p e d i n u n i t y, a n d n o t a s t h e c o n s e c u ti v e a d d i t i o n o f t h es e p a r a t e w o r k o f e a c h o f t h e e x p e r t s .

T h e b a s i c s d o c u m e n t s f o r tu n n e l d e s i g n s h o u l d i n c l u d e o rcover :

• T h e g e o l o g i c a l r e p o r t p r e s e n t i n g t h e r e s u l t s o f th eg e o l o g i c a l a n d g e o p h y s i c a l s ur v e y.

• T h e h y d r o g e o l o g i c a l r e p o rt .• T h e g e o t e c h n i c a l r e p o r t o n s it e i n v e s t i g at i o n s , i n c l u d i n g

t h e i n t e r p r e t a t i o n o f t h e r e s u l t s o f s it e a n d l a b o r a t o r y t e s tsw i t h r e s p e c t to t h e t u n n e l l i n g p r o c es s , so i l a n d r o c k

c lass i f i ca t ion , e tc . ,• I n f o r m a t i o n o n l i n e , cr o s s - s e c t io n , d r a i n a g e , a n d

s t r u c t u r a l e l e m e n t s a f f e c t i n g l a t e r us e o f t h e t u n n e l .

Tunn e l l ing an d Un derground Space Techno logy Vol.3, No. 3. pp. 237-249. 1988 . 0886-7798/883.00+ 0 0Printed n GreatBritain. Pergamon Presspie 237


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• Plans for and a descripti on of the projected excavation ordrivi ng procedure, i ncl udi ng the different cross-sectionsrelated to different ground conditions.

• Design documents for the types of excavation methodsand tunnel supports likely to be applied, considering,e.g. excavation advance and face support (types andnumber of anchors, shotcrete strength, closure length,etc. ).

• The prog ram for the in-situ monit oring of the tunnel byfield measurements.

• The analysis of stresses an d deformat ions (for unl ine dtunne ls as well as for single-or double -lined tunnels), andthe dimen sioni ng of the tunnel support for intermediatephases and final linings.

• The design for waterproofing or drainage.• Structural documents for the final design of the tunnel

project, including the detailing.• During and after the excavation, reports on the field

measurements and interpretation of their results withrespect to the response of the gro und a nd the structu ralsafety of the tunnel.

• Document ation of the problems encountered duri ng theexcavation and measures applied, e.g. stren gthe ning thegro und or ch ang ing the projected type of support, basedon monit oring results.

The above sequence of these basic documents also providesthe general out line of the design procedure.

2 .2 . E l em e n t s o f h e S t r u c t u r a lD e s i g n M o d e f o r Tunnels

In planni ng, designing, analysing and detai l ing astructure, engineers promise that the structure will neithersuffer structurall y nor collapse dur ing its projected lifetime.Thus , models of the reality are necessary for analysis in orderto predict the behaviour of a tunnel du ring the excavation andduring its lifetime. Models are also needed for bidding onprojects.

The following main elements involved in the designprocedure are shown as a flow-chart in Fig. 1:

1) Geolog~ and site investigations must confirm the line,orientation, depth, etc., of the opening, e.g. a cavern.

(2) Ground probing and soil or rock mechanics must beapplied to determine the gro und characteristics, e.g. prim arystresses, soil or rock strength, fault s, water condi tion s.

Geology •

Geotechrf ical ~ Gro un d haracter is t ics: ]I n v e s t i g a t i o n s Prim, stress, strength,w a t e r, p

fissures, anisotropy, etc.

E x p e r i e n c e I Excava t ion e thod ]mrEstimation • Strtctural Eleme tlts ] I

iOdel ¢0 ~ ~

FailureH y p o t h e s e s

iRisk Assessment ' I Con tractual spects ]

FieldM e a s u r e m e n t s

For the a ctual state only

unknown safety margin

fI O o t h o o o n s t I

1 In Situ Monitorirlg:Deforma tions stop? I

Safe

Figure 1. Design process/or tunnelling.

(3) Exper ience and preliminar)2 estimates or alculatzon,~are used to determi ne the cross-section requir ed and the choiceof the excavation metho d or tim tun nel drivi ng machine to beused, as well as the methods of dewater ing the grou nd and theselection of the suppo rti ng structural elements.

(4) After steps (1)-(3) are completed, tim tunuellingengin eer must derive, or even invent, a structural model. Byapplying equilibrium and compatibility conditions to themodel, the engineer has to arrive at those criteria that a~efactors in deci din g wheth er or no t the design is safe. Differentmodels may be used for each excavation phase, for tilepreliminary and the final tunnel lining, or for differentgrou nd behavio ur, e.g. in disc onti nuous rock or homo-gene ous soft soil. Mode lli ng of the geometri{ features mayvary greatly, depending on the desired intensity of theanalysis.

(5) A safety concept dra wn fr om fai lure hypotheses may bebased on criteri a such as strains, stresses, defor mati on, orfailure modes.

The bypass in Fig. 1 indicates that for many unde rgroundstructures, as in min in g or in self-sup portin g hard rock, nodesign models at all are applied. In such cases, pastexperiences alone may be sufficient.

Risk assessment by the contractor as well as by the owner isneeded at the time of contract negotiations. Risks involvepossible structural failures of the t unnel support and lining,functional failures after completion of work, and financialrisks. The contractual aspects also include risk sharing andrisk responsibilities.

In-situ monit orin g can be applied only after the tunnel linghas begun. If the displacements stop increa sing over time, itgener ally may be assumed t hat the str ucture is designed safely.Yet mon it ori ng provides only part of the answer to thequestion of safety, for it does not tell how close the structuremay be to sudden collapse or non lin ear failure modes. Theresults of field measurements and experiences duringexcavation may compel the engineer to change the designmodel by adjusti ng it to real behaviour.

An iterative, step-by-step approach is characteristic of thedesign of structures in the ground that employ the

part ici pati ng strength of the groun d (see loops in Fig. 1). Thedesigner may begin by applying estimated and simplebehaviou ral models. Adjustme nts based on actual experiencesduri ng the tu nnel lin g excavation (such as excavating theinitial section in the same ground conditions or driving apilot tunne l) will bring the model closer to reality and refine it(if refinement is consistent with the overall accuracyattainable). The interpretations of in-situ measurement s (andsome back analyses) also may assist designers in mak in g theseadjustments.

All of the elements of the structural design model i n Fig. 1should be considered an interacting unity. Scattering ofparameters or inaccuracy in one pa rt of the model will affectthe accuracy of the model as a whole. Therefore, the samedegree of simplicity or refinement should be provided

consistently through all the elements of the design model. Forexample, it is inconsistent to apply very refined mathematica ltools simul tane ousl y with rou gh guesses of importa ntgrou nd characteristics.

2 3 Diffe ren t pproaches Based onGround C ondi tions and Tunne l l ing Methods

The response of the ground to excavation of an open ing canvary widely. Based on the type of groun d in which t un nel li ngtakes place, four princip al types of tunn ell ing may be defined:

(1) for cut-and-cover tunnel lin g, in most cases the gro undacts only passively as a dead load on a t unne l structure erectedlike any aboveground eng ineer ing structure.

(2) In soft ground, immedia te support must be provided bya stiff lin in g (as, for example, in the case of shield-driventunnels with tubbings for ring support and pressurized slurry

238 TUNNELLING AND.UNDERGROUND SPACE TECHNOLOGY Volu me 3, Nu mb er 3, 1988


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f o r f a c e s u p p o r t ) . I n s u c h a c a s e , t h e g r o u n d u s u a l l yp a r t i c i p a t e s a c t iv e l y b y p r o v i d i n g r e s is t a n ce t o o u t w a r dd e f o r m a t i o n o f t h e l i n in g .

( 3 ) I n m e d i u m - h a r d r o c k o r i n m o r e c o h e s i v e s o i l , t h eg r o u n d m a y b e s t r o n g e n o u g h t o a l l o w a c e rt a i n o p e n s e c t i o na t t h e t u n n e l f a c e . H e r e , a c e r t a i n a m o u n t o f s tr e s s r e l e a s e m a yp e r m a n e n t l y b e v a l i d b ef o r e t h e s u p p o r t i n g e l e m e n t s a n d t h el i n i n g b e g i n a c t i n g e f f e c ti v e ly. I n t h i s s i t u a t i o n o n l y af r a c t i o n o f t h e p r i m a r y g r o u n d p r e s s u r e is a c t i n g o n t h el i n i n g .

( 4 ) W h e n t u n n e l l i n g i n h a r d r o c k , t h e g r o u n d a l o n e m a yp r e s e r v e t h e s t a b i l i t y o f th e o p e n i n g s o t h a t o n l y a t h i n l i n i n g ,i f a n y, w i l l b e n e c e s s a r y f o r s u r f a c e p r o t e c t i o n . T h e d e s i g nm o d e l m u s t t a k e i n t o a c c o u n t t h e r oc k a r o u n d t h e tu n n e l i no r d e r t o p r e d i c t a n d v e r i f y s a f e t y c o n s i d e r a t i o n s a n dd e f o r m a t i o n s .

E s p e c i a l l y i n g r o u n d c o n d i t i o n s t h a t c h a n g e a l o n g t h et u n n e l a x i s , t h e g r o u n d m a y b e s t r e n g t h e n e d b y i n j e c t i o n s ,a n c h o r i n g , d r a i n i n g , f r e e z in g , e tc . U n d e r t h e s e c ir c u m s t a n c e s ,c a s e (2 ) m a y b e i m p r o v e d , a t l e a s t t e m p o r a r i l y, t o c a s e (3 ).

T h e c h a r a c t e r i s t i c s tr e s s r e l e a se a t t h e t u n n e l f a c e ( E r d m a n n1 98 3) i s s h o w n i n F i g s 2 a n d 3 . T h e r e l a t i v e c r o w n d i s p l a c e -m e n t w i s p l o t t e d a l o n g t h e t u n n e l a x i s , w h e r eW/Wo = 1.0r e p r e se n t s t h e c a se of a n u n s u p p o r t e d t u n n e l . I n m e d i u m -

s t i ff g r o u n d n e a r l y 8 0% o f t h e d e f o r m a t i o n s h a v e a l r e a d y t a k e np l a c e b e f o r e t h e l i n i n g ( s h o w n h e r e a s s h o t c r e t e ) i s s t i f fe n o u g h t o p a r t i c i p a t e .

.Lu=O:~Ok . . . . . . . . . . . . .P E w

0 ,41 . . . . . . . . . _ L _ . . . . . . ~ 0 _ _

0,1 j / s t ross . , .0 .

, ° / w ~without l l n l n g T- - - - - - - ' ' ~ - -. . . . . " ¢ - ~ : - 0 "

w w o

Figure 2. Crown displacement w along the axis, ahead andbeyond t he t unnel ]ace.

1,0

O.8

0 6

0 4

0 ,2

0

O hO ° = Y H ' ~ g ° = ~ v = 0 ,5

=

l - l i o L o o o r o ;, L L

d =0,30ol ='( L u ~

l o ~ / o o

100

p i o n e s y s t e 0 1

- - - L . : 0 . 25 D

- . - L u : 0 , 5 0 D

E K5 0 0 1 0 0 0 1 5 0 0 2 0 ( ] 0 H N / m

Figure 3. G round stresses acting on the li ning as fractions ofthe primary stress Erdmann 1983).

F o r a s i m p l i f i e d p l a n e m o d e l w i t h n o s t re s s r e l e as e , w h e r et h e f u l l p r i m a r y s t r e ss e s a r e a s s u m e d t o a c t o n a l i n e d o p e n i n g ,t h e d i s p l a c e m e n t m a y b e o n l y 0 . 4 o f t h a t o c c u r r i n g i n t h eu n s u p p o r t e d c as e. T h e c o r r e s p o n d i n g s t re s s r e le a s e i s s h o w ni n F i g . 3. T h e s i m p l i f i e d e x a m p l e , c o n s i d e r i n g o n l y t h ec o n s t a n t p a r t o f r a d i a l p r e s s u r e , y i e l d s t h e v a l u e s s h o w n f o r ar i n g s t i f fn e s s o fEsA = 1 5, 00 0 x 0 . 3 = 4 5 00 M N / m a n d a g r o u n dd e f o r m a t i o n m o d u l u s o f EK = 10 00 M N / m 2 .

E v e n i n t h e u n r e a l i s t i c ca s e w h e n t h e f u l l p r i m a r y s t r e ss a c t ss i m u l t a n e o u s l y o n t h e g r o u n d o p e n i n g a n d t h e l i n i n g , o n l y5 5% o f t h e s t r e s s i s t a k e n b y t h e l i n i n g ; i n t h e c a s e o f EB A =2250 M N / m , o n l y 3 8% is ta k e n b y t h e l i n i n g . I f a n o p e ns e c t i o n o f 0 .2 5 o f t h e t u n n e l d i a m e t e r i s l e f t w i t h o u t l i n i n gs u p p o r t , t h e l i n i n g t a k e s o n l y 2 5 % o f t h e p r i m a r y s t re s s es ; f o rL o = 0 .5 D, i t t akes on l y 12% of the p r im ary s t resses .

F o r v e ry so f t g r o u n d r e q u i r i n g i m m e d i a t e s u p p o r t ( a s i n t h ec a se o f v e ry s h a l l o w t u n n e l s) , a l m o s t 1 00 % o f t h e p r i m a r ys t re s s es a r e a c t i n g o n t h e l i n i n g . T h e v a l u e s c h a n g e , o f c o u r s e ,w i t h o t h e r s t i f f n e s s r e l a t i o n s h i p s a n d o t h e r s t r e s s d i s t r i b u -t i o n s t h a n t h o s e s h o w n i n F i g . 3, w i t h o t h e r c r o s s - se c t i o n s ,a n d o t h e r t u n n e l l i n g m e t h o d s .

2 . 4 . Site Investigations StructuralAnalysis and I n - S i t u Monitoring

A n a d e q u a t e i n t e n s i t y o f s i te e x p l o r a t i o n , f r o m w h i c hg e o l o g i c a l a n d h y d r o l o g i c a l m a p p i n g s a n d g r o u n d p r o f i le sa r e d e r i ve d , is m o s t i m p o r t a n t f o r c h o o s i n g t h e a p p r o p r i a t et u n n e l d e s i g n a n d e x c a v a t i o n m e t h o d . A w e l l - d o c u m e n t e dg e o l o g i c a l r e p o r t s h o u l d p r o v i d e a s m u c h i n f o r m a t i o n a s i so b t a i n a b l e a b o u t t h e p h y s i c a l f ea t u re s a l o n g t h e t u n n e l a x i sa n d i n t h e a d ja c e n t g r o u n d . T h e a m o u n t o f i n f o r m a t i o ns h o u l d b e m u c h g r e a te r t h a n t h e i n f o r m a t i o n r e q u i r e d f o re n t e r i n g d i r e c t l y i n t o a s t r u c t u r a l a n a l y s i s .

T h e r e s u lt s o f a n a n a l y s i s d e p e n d v e r y m u c h o n t h ea s s u m e d m o d e l a n d t h e v a lu e s o f t h e s i g n i fi c a n t p a r a m e t e rs .T h e m a i n p u r p o s e s o f t h e s t ru c t u r a l a n a l y s i s a r e to p r o v i d et h e d e s i g n e n g i n e e r w i t h : ( 1 ) a b e t t e r u n d e r s t a n d i n g o f t h eg r o u n d - s t r u c t u r e i n t e r a c t i o n i n d u c e d b y t h e t u n n e l l i n gp r o c es s ; (2 ) k n o w l e d g e o f w h a t k i n d s o f p r i n c i p a l r i sk s a r ei n v o l v e d a n d w h e r e t h e y a r e l o c a te d ; a n d ( 3 ) a t o o l f o ri n t e r p r e t a t i n g t h e s i te o b s e r v a t i o n s a n d t h ein-situm e a s u r e m e n t s .

T h e a v a i l a b l e m a t h e m a t i c a l m e t h o d s o f a n a l y s i s a r e m u c hm o r e r e f i n e d t h a n a r e t h e p r o p e r t i e s t h a t c o n s t i t u t e t h es t r u c t u r a l m o d e l . H e n c e , i n m o s t c a se s i t is m o r e a p p r o p r i a t et o i n v e s t i g a t e a l t e r n a t i v e p o s s i b l e p r o p e r t i e s o f th e m o d e l , o re v e n d i f f e r e n t m o d e l s , t h a n t o a i m f o r a m o r e r e f i n e d m o d e l .F o r m o s t c a s e s , i t i s p r e f e r a b l e t h a t t h e s t r u c t u r a l m o d e le m p l o y e d a n d t h e p a r a m e t e r s c h o s e n f o r t h e a n al y s e s b el o w e r - l i m i t c a se s t h a t m a y p r o v e t h a t e v e n f o r u n f a v o u r a b l ea s s u m p t i o n s , t h e t u n n e l l i n g p r o c e s s a n d t h e f in a l t u n n e l a r es u f f i c i e n t l y sa f e. I n g e n e r a l , t h e s t r u c t u r a l d e s i g n m o d e l d o e sn o t t r y to r e p r e s e n t e x a c t l y t h e v e r y a c t u a l c o n d i t i o n s i n t h e

t u n n e l , a l t h o u g h i t c o v e r s t h e se c o n d i t i o n s .In-situ m o n i t o r i n g i s i m p o r t a n t a n d s h o u l d b e a n i n t e g r alp a r t o f t h e d e s i g n p r o c e d u r e , e s p e c i a l l y i n c a se s w h e r es t a b i l it y o f t h e t u n n e l d e p e n d s o n t h e g r o u n d p r o p e r t ie s .D e f o r m a t i o n s a n d d i s p l a c e m e n t s g e n e r a l l y c a n b e m e a s u r e dw i t h m u c h m o r e a c c u r a c y t h a n s tr e ss e s. T h e g e o m e t r y o f th ed e f o r m a t i o n s a n d t h e i r d e v e l o p m e n t o v e r t i m e a r e m o s ts i g n i f i c a n t f o r t h e i n t e r p r e t a t i o n o f t h e a c t u a l e v e n t s .H o w e v e r ,in-situ m o n i t o r i n g e v a l u a te s o n l y t h e v er y l oc a l a n da c t u a l s i t u a t i o n i n t h e t u n n e l . T h e r e f o r e , i n g e n e r a l t h ec o n d i t i o n s t a k e n i n t o a c c o u n t b y t h e d e s i g n c a lc u l a t i o n s d on o t c o i n c i d e w i t h t h e c o n d i t i o n s t h a t a r e m o n i t o r e d . O n l y b yr e l a t i n g m e a s u r e m e n t r e s u lt s a n d p o s s i b l e f a il u r e m o d e s b ye x t r a p o l a t i n g c a n t h e e n g i n e e r a r r iv e a t c o n s i d e r a t i o n s o fs a f et y m a rg i n s .

I n m a n y c a s es , e x p l o r a t o r y t u n n e l l i n g m a y b e r e w a r d i n gb e c a u s e o f t h e i n f o r m a t i o n i t y i e l d s o n t h e a c t u a l r e s p o n s e o ft h e g r o u n d t o th e p r o p o s e d m e t h o d s f o r d r a i n a g e , ex c a v a t i o n ,

Vo lum e 3 , N um be r 3 , 1988 TUNNELLING AND UNDERGROUND SPACE TECHN OLOG Y 239


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TBM driv ing, support, etc. In im por tan t cases a pilot tun nelmay be driven; such a tunne l may even be enlarged to the fullfinal tunnel cross-section in the most representative groundalo ng the t unne l axis. For larger projects, it may be useful toexcavate a trial tunne l prior to com men cin g the actual work.More intensive i n - s i t u monit oring of the exploratory tunnelsections should check the design approach by numericalanalysis.

2 5 Design Criteria and

Evaluating Structural SafetyAn un der gro und structure ma y lose its serviceability or itsstructural safety in the following cases:-- The structure loses its watertightness.

The deformations are intolera bly large.-- The t unne l is insuffic ientl y durabl e for its projected life

and use.-- The ma terial strength of the structural elements is

exhausted locally, necessita ting repair.-- The suppo rt techni que (for example, in erecting

segmental l inings) fails or causes damage.-- Exha usti on of the material strength of the system causes

structural failure, althou gh the correspondi ng deforma-tions develop in a restrained man ner over time.

-- The tun nel collapses suddenly because of instability.

The struct ural design model shoul d yield criteria related tofailure cases, against which the tunnel should be designedsafely. These criteria may be:

• Deformations and strains.• Stresses an d uti liz ati on of plasticity.• Cross-sectional lini ng failure.• Failure of grou nd or rock strength.• Limit-a nalysis failure modes.

In pr incipl e, the safety margins may be chosen differently foreach of the failure cases listed above. However, in reality theevalu atio n of the actual safety margins is most complex an dvery much affected by the scattering of the in volved propertiesof the ground and the structure and, furthermore, by theinteracting probabilistic characteristics of these properties.

Therefore, the results of any calcul atio n should be subject tocritical reflection on their relevance to the actual conditions.1

National codes for concrete or steel structures may notalways be appropriate for the design of tunnels and thesupporting elements. Computational safety evaluationsshould always be complemented by overall safetyconsiderations and risk assessments employing criticalengineeri ng judgment, which may include the followingaspects:

• The grou nd characteristics should be considered in ligh tof their possible deviations from average values.

• The design model itself and the values of parametersshould be discussed by the design team, which includesall of the experts inv olve d (see Section 2.1, Gen era lProcedure in Designing a Tunn el , above).

• Several and more s imple ca lcula tion runs withparametric variations may uncover the scattering of theresults. In general, this approach is much moreinformati ve than a single over-refined investigatio n.

• The i n - s i t u measurements should be used for successiveadju stmen t of design models.

• Long-term measurement of deformations via extra-pol ati on may reveal to a large extent the final stability ofthe structure, although sudden collapse may not beannoun ced in advance.

3 . S i t e I n v e s t i g a t i o n sa n d G r o u n d P r o b in g s3 1 G e o l o g i c a l D a t a and Ground P a r a m e t e r s

The appropriate amo unt of ground investigations on siteand in laboratories may vary considerably from project to

project. Because the types of ground explorations andprobings depend on the special features of the tunnellingproject, i t s purpose, excavation method, etc., they should bechosen by the expert team, especially in consuha tio n with thedesign engineer. The int ensity of the ground explor ationswill depend on the homogeneity of the ground, the purpose ofthe tu nne lli ng, the cost of boring, e.g. for shallow or deep(over, and other factors.

The geological investigations should inclu de the followingbasic geotechnical infor mati on (see also ISRM Co mmissi onon Cl assi fica tio n of Rocks an d Rock Masses 1981).

3.1 .1 . Tunn els in rock

Z o n i n g .The grou nd should be divided in geotechnical unitsfor which the design characteristics may be consideredunifor m. However, relevant characteristics may displayconsiderable variations within a geotechnical unit. Thefollowing aspects should be considered for the geologicaldescription of each zone:

Name of the geological formation in accordance with agenetic classification.

• Geologic structure and fracturing of the rock mass withstrike and dip orientations.

• Colour, texture and minera l composition.

• Degree of weatheri ng.P a r a m e t e r s o f t h e r o c k m a s se.g. in five classes of intervals,

including:

• Thi ckne ss of the layers.• Frac ture intercept.• Rock classification.• Core recovery.• Unia xia l compressive strength of the rock, derived from

labora tory tests.• Angl e of frict ion of the fractures (derived from labor atory

direct shear tests).• Strength of the ground in on-site situations.• Deformation properties (modulus).• Effect of water on the rock quality.• Seismic velocity.

P r i m a r y s t re s s J i e ld o J t h e g r o u n d .For larger tunnelprojects, tests eva lua tin g the nat ura l stresses i n the rock massmay be recomme nded. For u sual tun nel t~roiects one ~houldleast estimate the stress ratio oh /ov at tUlUltzi lt~Vca, Wtle lt; h ISthe lateral gr oun d pressure and ov the major princ ipal stress(usually in the vertical direction), for which the weight of theoverlying rock generally may be taken. Tectonic stressesshould be indicated.

Wa t e r c o n d i t i o n s .Two types of infor mati on about watercondit ions are required:

(1) Permeability, as determined by:Coefficient k (m/s) (from field tests).Lugeo n u nit (from tests in boreholes).

(2) Water pressure:At the tunn el level (hydraulic head).At piezometric levels in boreholes.D e J o r m a b i l i ty o J t h e r o c k m a s s . I n - s i t utests are require d to

derive the two different deformation moduli, which can bedetermined either from static methods (dilatometer tests inboreholes, plate tests in adits, or radial jacking tests inchambers) or from dynamic methods (wave velocity byseismic-refraction or by geophysical l ogging in boreholes).Engine ering judgment should be exercised in choosing thevalue of the modulus most appropriate for the design--forinstance, by the relevant tangent of the pressure-deformationcurve at the primary stress level in the static method.

Properties for which inf ormatio n is needed when tunnelbori ng machines are to be employed include:- -

Abrasiveness and hardness.- - Mineral composites, as, e.g. quartzite contents.-- Homogeneity.

240 TUNNELLI NG AND UNDERGROUND SPACE TECHNOLOGY Volu me 3, Numb er 3, 1988


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Swel l ing po ten t ia l o f the rock .T h e p r e s e n c e o f s u l f a t e s ,h y d r o x y d e s , o r c l a y m i n e r a l s s h o u l d b e i n v e s t i g a t e d b ym i n e r a l o g i c a l t e s ti n g . A s p e c i a l o d e o m e t e r t e st m a y b e u s e d t od e t e r m i n e t h e S w e l l te s t - cu r v e o f a s p e c i m e n s u b j e c t e d f i r s t t o al o a d - u n l o a d - r e l o a d c y cl e i n a d r y s ta t e, a n d t h e n u n l o a d e dw i t h w a t e r.

T h e f o l l o w i n gg r o u n d w a t e r c o n d i ti o n ss h o u l d b e g i v e n :- - W a t e r l ev e l s , p i e z o m e t r i c l e v e ls , v a r i a t i o n s o v e r t i m e ,

p o r e p r e s s u r e m e a s u r e m e n t s i n c o n f i n e d a q u i f e rs .- - Wa t e r c h e m i s t ry.- - Wa t e r t e m p e r a t u re s .- - E x p e c t e d a m o u n t o f w a t e r i n f l o w.

3.1.2 . Tunnels in soi l

T h e g e o t e c h n i c a l d e s c r i p t i o n s h o u l d p r i m a r i l y f o ll o w t h er e c o m m e n d a t i o n s g i v e n a b o v e f o r r o c k . A d d i t i o n a l s p e c i a lf e a t u r e s f o r s o i l i n c l u d e :

1. Soil identif icat ion( l a b o r a t o r y t e s t i n g ) :

• P a r t i c l e s iz e d i s t r i b u t i o n .• A t t e r b e rg l i m i t s w l , w p .• U ni t w e igh t s , % ~ /d , ~ /z .• W a t e r c o n t e n t w.• P e r m e a b i l i t y k.

• C ore recovery.2. Me chanica l p roper t iesd e t e r m i n e d b y l a b o r a t o r y t e s t i ng :

• F r ic t ion ang le 4~u , ~ .• Co hes ion cu , c .• Co m pre ss ib i l i ty m~, c~ .

3. Mech anica l p roper t iesd e t e m i n e d b y f i e l d t e s t i n g :

• S hear s t reng th r~ (Vane- tes t ) .• P e n e t r a t i o n N ( S t a n d a r d P e n e t r a t i o n Te s t ) .• D e f o r m a b i l i t y E ( P l a t e b e a r i n g , D i l a t o m e t e r ) .

4 . G r o u n d w a t e r c o n d i t i o n( i n a d d i t i o n t o t h o s e l i s t e d i n3 . 1. 1 .) : p e r m e a b i l i t y , a s d e t e r m i n e d b y p u m p i n g t es t s.

3 2 Evaluation of Parameters by GroundProbing and a b o r a t o r y Te s t s

T h e p r o p e r t i e s o f th e g r o u n d t h a t a r e r el e v a n t fo r t h e t u n n e ld e s i g n s h o u l d b e e v a l u a t e d a s c a r e f u l l y a s p o s s i b l e ,l n - s i t ut e st s , w h i c h c o v e r l a rg e r g r o u n d m a s s e s , g e n e r a l l y a r e m o r es i g n i f i c a n t t h a n a r e l a b o r a t o r y t es ts o n s m a l l s p e c i m e n s ,w h i c h o f t e n a r e t h e b e t t e r p r e s e r v e d p a r t s o f t h e c o r i n g . T h en a t u r a l s c a t t e r in g o f g r o u n d p r o p e r t i e s r eq u i r e s a na p p r o p r i a t e n u m b e r o f p a r a l l e l t e s t s - - a t l e as t th r e e t es ts fo re a c h p r o p e r t y ( se e a l s o t h e c o r r e s p o n d i n g I S R M r e c o m -m e n d a t i o n s ) .

R e s u l t s o f l a b o r a t o r y t e s t s m u s t b e a d j u s t e d t o s i t ec o n d i t i o n s . T h e s iz e o f s p e c i m e n , t h e e ff e c ts o f g r o u n d w a t e r,t h e i n h o m o g e n e i t y o f th e g r o u n d o n s i t e , a n d t h e ef f ec t s o f

s c a t t e r in g m u s t b e c o n s i d er e d . T h e c o n c l u s i o n s d r a w n f r o mt es ts a ls o s h o u l d t a k e i n to c o n s i d e r a t i o n w h e t h e r t h es p e c i m e n s w e r e t a k e n f r o m d i s t u r b e d o r u n d i s t u r b e d g r o u n d .

I n m a n y c a se s , th e f i rs t p a r t o f t h e t u n n e l l i n g m a y b ei n t e r p r e t e d a s a l a rg e - s c a le te s t, t h e e x p e r i e n c e s f r o m w h i c hm a y b e d r a w n u p o n n o t o n l y f o r t h e s u b s e q u e n t e x c a v a t i o n sb u t a l s o f o r p r e d i c t i n g g r o u n d b e h a v i o u r. I n c e r t a i n c a se s ,l o n g h o r i z o n t a l b o r e h o l e s m a y f a c i l i ta t e g r o u n d p r o b i n ga h e a d o f t h e f a c e , o r a p i l o t t u n n e l m a y s e r v e a s a t e s t t u n n e lt h a t a t t h e s a m e t i m e p r o v i d e s d r a i n a g e . T h e o n - s it ei n v e s t i g a t i o n s p r o v i d e v a l u a b l e r e s u l t s f o r c h e c k i n g t h ec o r r e l a t i o n o f l a rg e - s c a lein -s i tu t e st s w i t h l a b o r a t o r y t e s ts .

S p e c i a l t e s t s t h a t c o r r e s p o n d d i r e c t l y t o t h e p r o p o s e dt u n n e l l i n g m e t h o d m a y b e r e q u i r e d , e . g . f o r t h e s u f f i c i e n tp r e s e r v a t i o n o f a m e m b r a n e a t t h e f a ce o f a b e n t o n i t e s h i e l d .

T h e e v a l u a t i o n o f t h e p a r a m e t e r s s h o u l d i n d i c a t e t h ee x p e c t e d s c a tt e r in g . F r o m p r o b a b i l i s t i c c o n s i d e r a t i o n o fn o r m a l l y d i s t r i b u t e d q u a n t i t i e s i t c an b e d e d u c e d t h a t a m e a n

v a l u e o r a v a l u e c o r r e s p o n d i n g t o a m o d e r a t e l y c o n s e r v a ti v ef r a c ti l e o f a G a u s s i a n d i s t r i b u t i o n i s m o r e a p p r o p r i a t e t h a nt h e w o r s t c a s e v a l u e .

A s e t o f a l l th e p a r a m e t e r s d e s c r i b i n g t h e g r o u n d b e h a v i o u ro f o n e t u n n e l s e c t io n w i t h r e g a r d t o t u n n e l l i n g s h o u l d b e s e ena s a c o m p r e h e n s i v e u n i t a n d s h o u l d b e w e l l - b a l a n c e d i nr e l a t i o n t o e a c h o f t h e p a r am e t e r s . F o r e x a m p l e , a s m a l l v a l u eo f g r o u n d d e f o r m a t i o n m o d u l u s i n d i c at e s a t e n d en c y t op l a s t i c b e h a v i o u r , t o w h i c h c o r r e s p o n d s a r a t i o o f l a t e r a l tov e r t i c a l p r i m a r y s t r e s s t h a t i s c l o s e r t o1 . 0 . H e n c e , f o ra l t e r n a t i v e i n v e s t i g a t i o n s s o m e c o m p l e t e , b a l a n c e d s e t s o fp a r a m e t e r s s h o u l d b e c h o s e n i n s t e a d o f c o n s i d e r i n g e ac hp a r a m e t e r a l o n e , u n r e l a t e d t o t h e o t h e r s .

T h e a v a i l a bl e m e t h o d s f o r g r o u n d p r o b i n g a n d l a b o r at o r yt e st s , t h e i r a p p l i c a b i l i t y a n d a c c u r a c y a r e g i v e n i n t h eA p p e n d i x .

3 . 3 . I n t e r p r e t a t i o n o f Te s tR e s u l t s a n d D o c u m e n t a t io n

T h e f i e ld a n d l a b o r a t o r y t es ts s h o u l d b e g i v e n i n w e l l -d o c u m e n t e d r e p o r t s , i n t h e f o r m o f a c t u a l r e s u l t s. B a s e d o nt h e s e re p o r t s , a n i n t e r p r e t a t i o n o f t h e t e s ts t h a t i s r e le v a n t t ot h e a c t u a l t u n n e l l i n g p r o c e ss a n d t h e r e q u i r e m e n t s o f th ed e s i g n m o d e l s f o r t h e s t r u c t u r a l a n a l y s i s i s n ec e s s a ry. A t t h et i m e t h e t e s ts a r e p l a n n e d , t h e t e a m o f e x p e r t s r e f e rr e d t o i n

S e c t i o n 2.1 s h o u l d d e c i d e w h i c h g r o u n d p r o p e r t i e s a n dg r o u n d c h a r a c t e r i s t i c s a re n e c e s s a r y f o r t h e g e n e r a lg e o t e c h n i c a l d e s c r i p t i o n of t h e g r o u n d a n d f o r th e p r o j e c t e dd e s i g n m o d e l . T h u s , a c lo s e r r e l a t i o n s h i p m a y b e a c h i e v e db e t w e e n g r o u n d i n v e s t i g a t i o n s a n d t u n n e l l i n g d e s i g n , a n db e t w e e n t h e a m o u n t a n d r e f i n e m e n t o f te st s a n d t h et u n n e l l i n g r is k s.

T h e d o c u m e n t s s h o u l d l a y o p e n t h e r a t i o n a l i n t er -p r e t a t i o n a l w a y i n w h i c h d e s i g n v a l u e s a re d e r i v e d f r o m t e str e s u l ts . T h i s m e t h o d h a s p r o v e n t o b e e s p e c i a l l y u s e f u l i n t h et e n d e r i n g p r o c e s s , b e c a u s e i t c o n d e n s e s t h e r e l e v a n t d a t a f o rt h e d e s c r i p t i o n o f th e g r o u n d a n d f o r th e d e s i g n o f t he t u n n e lo n a b a n d a l o n g t h e t u n n e l a x i s b e n e a t h a g r a p h i c a lr e p r e s e n t a t i o n o f t h e t u n n e l p r o f i l e (s ee th e e x a m p l e s i n F i g s9-13) .

S u c h c o n d e n s e d t a b l e s m a y b e p r e p a r e d f i r s t f o r t e n d e r i n ga n d t h e p r e l i m i n a r y d e s ig n , a n d t h e n i m p r o v e d t h r o u g he x p e r i e n c e g a i n e d a n d i n c o m i n g m o n i t o r i n g r e s u l t s .H o w e v e r, i t s h o u l d b e c l e a r l y s t a t e d , e s p e c i a l l y i n t h e c o n t r a c tp a p e r s , t h a t m u c h r e l e v a n t i n f o r m a t i o n i s l o s t o ro v e r s i m p l i f i e d i n s u c h t a b l e s , a n d t h a t t h e r e f o r e t h eg e o t e c h n i c a l r e p o rt s a n d o t h e r c o m p l e t e d o c u m e n t s s h o u l d b ec o n s i d e r ed t h e p r i m a r y d o c u m e n t s .

4 . O n S t r u c t u r a l D e s i g nM o d e l s f o r Tu n n e l li n g

4 1 Alternative Design ModelsT h e e x c a v a t i o n o f a t u n n e l c h a n g e s t h e p r i m a r y s tr e ss f ie l d

i n t o a t h r e e - d i m e n s i o n a l p a t t e r n a t t h e t u n n e l l i n g f a c e .F a r t h e r f r o m t h e f a ce , t h e s tr e ss f i e l d e v e n t u a l l y w i l l r e t u r n t oa n e s s e n t i a l l y t w o - d i m e n s i o n a l s y s te m . T h e r e f o r e , t h e tu n n e ld e s i g n m a y c o n s i d e r o n l y t w o - d i m e n s i o n a l s t re s s -s t ra i n f ie l dsa s f ir s t a p p r o x i m a t i o n s .

T h e d e s i g n o f a t u n n e l s h o u l d t a k e i n t o a c c o u n t t h ei n t e r a c t i o n b e t w e e n g r o u n d a n d l i n i n g . I n o r d e r t o d o s o, t h el i n i n g m u s t b e p l a c e d i n c lo s e s t p o s s i b l e b o n d w i t h t h eg r o u n d . To p r e se r v e i t s n a t u r a l s t r en g t h , t h e g r o u n d s h o u l db e k e p t a s u n d i s t u r b e d a s p o s s i b l e . T h e d e f o r m a t i o n sr e s u l t i n g f r o m t h e t u n n e l l i n g p r o c e s s ( s e e F i g . 2 ) r e d u c e t h ep r i m a r y g r o u n d p r e s s u r e a n d c r e a te s tr es s es i n t h e l i n i n gc o r r e s p o n d i n g t o t h a t f r a c t i o n a l p a r t o f th e p r i m a r y s t r es s e s i nt h e g r o u n d w h i c h a c t o n t h e s u s t a i n i n g l i n i n g . T h es t r e s s e sd e p e n d o n t h e s ti f fn e s s r e l a t i o n s h i p o f t h e g r o u n d t o t he

l i n i n g , a s w e l l a s o n t h e s h a p e o f t h e t u n n e l c r o s s - s e c t i o n . T h el a t t e r s h o u l d b e s e l e c t e d s u c h t h a t a n a r c h i n g a c t i o n i n t h eg r o u n d a n d t h e l i n i n g m a y d e v e l o p .

Vo l u m e 3 , N u m b e r 3 , 1 9 8 8 TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 241


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® ©

] empiricat- ~ ~ approach

.~1.._i__O H ...Ko ~ ~_ .

Ov Ov OvOv

Figure 4 . Al te rna t ive p lane-s t ra in des ign m odels for d i ffe ren t depths and gr ound s ti ]]nesses .

Figure 4 presents four different structural models for aplane- strain design analysis. The cross-sections need not becircular. These four models are explained more expl ic i t lybelow.

In soft ground, immediate support is provided by arelatively stiff lining. For tunnels at shallow depth (as for

underground railways in cities), it is agreed tha t a two-dime nsio nal cross-section may be considered, neglect ing thethree -dime nsiona l stress release at the face of the tunne ldur in g excavation. In cases (1) and (2) in Fig. 4, the g roun dpressures acti ng on the cross-section are assumed to be equalto the primary stresses in the undi stur bed ground. Hence, it isassumed that in the final state (some years after theconstruction of the t unnel), the ground eventually will returnto nearly the same condition as before the tunnelling.Changes in gro und water levels, traffic vibrations, etc., mayprovoke this readju stment.

In case (1), for shallow tunnels and soft ground, the fulloverburden is taken as load. Hence, no tension bedding isallowed at the crown of the tunnel. The ground reaction issimplified by radial and tangential springs, arriving at a

bedded-beam model..In case (2), for moderate ly stiff ground , the soil stiffness isemployed by assuming a two-dimensional con tin uum modeland a complete bon d between lini ng and ground. As in case(1), stress release due to predeformations of the ground isneglected. Inward d isplacements result in a re duction of thepressure on the lining.

Case (3) assumes tha t some stress release is caused bydeformations tha t occur before the lin in g participates. Inmed ium -har d rock or in highly cohesive soil, the groun d maybe strong enough to allow a certain unsupported section atthe tunnel face (see Fig. 2). Also, for tunnels having a highoverburden, a reduction of the acting crown pressure(represented in Fig. 4 by h < H) is taken into account.

In case (4), the g rou nd stresses acti ng on the li ni ng are

determi ned by an empir ical approach, which m ay be based onprevious experiences with the same ground and the sametunnel l ing method, on in -s i tu observations and mo nito ring

of initial tunnel sections, on interpretation of the observeddata, and on conti nuous improvements of the design model.

If a plane m odel is not justif ied- -as is the case for caverns,for more complicated geometries of under grou nd structures,or for an investiga tion directly at the tunne ll ing face--a three-dimensional model may be necessary (see Fig. 5). The three-

dimensional model also may be conceived as consisting ofdiscont inuous masses (block theory) or a c ont inu um withdiscrete discontinuous fissures or faults.

a. b.~v

l l i H H l l i H l u n l l n

] l l[IJIIIIJIiJIl i l l lG,

Figu re 5a. Th ree -d imens ion a l co n t i nuum mode l .F igure 5b . Example of two-dimens ional ] in i te -e lementmodel .

4.2.o n t i n u u m o riscontinuum M o d e l

For structural design models such as those in Figs 5a and b,the ground may be modelled as homogeneous orheterogeneous, isotropic or anisotropic; as a two-dimensional, i.e. allowing some stress release before thelin ing is acting, or a three- dimensiona l stiff medium. The

lining may be modelled either as a beam element withbending stiffness or as a continuum. Plasticity, viscosity,fracture of the rock, no n-l ine ar stress-strain and def ormation

242 TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY Volu me 3, Numb er 3, 1988


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b e h a v i o u r , e tc ., m a y b e c o v e r ed b y s p e c ia l a s s u m p t i o n s f o rm a t e r i a l l a w s .

T h e d e s i g n c r i te r i a a re c o m p u t e d b y n u m e r i c a l s o l u t i o n s .F r o m t h e i r o r i g i n s , t h e f i n i t e - e l e m e n t m e t h o d a n d t h eb o u n d a r y - e l e m e n t m e t h o d a r e b a si c al ly c o n t i n u u m m e t h o d s.T h u s , h o m o g e n e o u s m e d i a a n d s t r e s s - s t r a i n f i e l d s a r ee v a l u a t e d b e s t . I n g e n e r a l , d i s c o n t i n u a s u c h a s r o c k w i t hf i s su r e s a n d f a u l t s , a n d f a i l u r e m o d e s , w h i c h a r e i n i t i a te d b yl o c a l r u p t u r e , s h e a r f a i l u re , o r f u l l c o l l a p s e , c a n n o t b e c o v e r e db y c o n t i n u u m m e t h o d s:

A c o n t i n u u m o r d i s c o n t i n u u m m o d e l i s a p p r o p r i a te f o rt u n n e l s t r u c t u r e s w h e r e t h e g r o u n d p r o v i d e s t h e p r i n c i p a ls t a b i l i t y o f t h e o p e n i n g ( a s i n h a r d r o c k ) o r w h e r e t h eg e o m e t r i c a l p r o p e r t i e s o f t h e u n d e r g r o u n d o p e n i n g c a n b em o d e l l e d o n l y b y n u m e r i c a l a n a l y s i s , e. g . in t h e c a se o f c l o s e lys p a c e d t w i n t u n n e l s .

4 .3 . B e d d e d - B e a m M o d e lA t i o n - R e a c t i o nM odel

I f t h e s t i f f n e s s o f t h e g r o u n d i s s m a l l c o m p a r e d t o t h es t if f n es s o f th e l i n i n g , a d e s i g n m o d e l s u c h a s t h a t s h o w n i nF i g . 6 m a y b e e m p l o y e d . I n s u c h a c a s e, t h e a c ti v e g r o u n dp r e s s u r e s a r e r e p r e s e n t e d b y g i v e n l o a d s a n d t h e p a s s iv er e a c t io n o f t h e g r o u n d a g a i n s t d e f o r m a t i o n s i s s i m u l a t e d b yc o n s t a n t b e d d i n g m o d u l i . T h e m o d e l m a y b e p a r t i c u l a r l yw e l l - s u i t e d t o t h e d e s i g n o f l i n i n g s o f s h i e ld - d r i v e n t u n n e l s .A s t o a p p l i c a b i l i t y, t h e s t if f n es s r a t i o f l m a y b e s m a l l e r t h a n200:

~8 = Es RS /E]< 200,w h e r e : E s i s t h e r e p r e s e n t a t i v e d e f o r m a t i o n s t if f n es s

m o d u l u s o f t h e g r o u n d ,R i s t h e r a d i u s o f t h e t u n n e l c r o s s - s e c t i o n o r i t s

e q u i v a l e n t f o r n o n - c i r c u l a r t u n n e l s ,E ] i s t h e b e n d i n g s t if f ne s s o f t h e l i n i n g .

A m o r e c o r r e c t s o l u t i o n f o r th e b e d d i n g i s g i v e n b y a n o n -z e r o st i ff n e s s m a t r i x f o r al l e l e m e n t s w i t h r e g a r d t o r a d i a la n dt a n g e n t i a l d i s p l a c e m e n t s .

H o w e v e r , i n m o s t c a s e s a n d i n v i e w o f t h e u n a v o i d a b l ea p p r o x i m a t i o n s b a s e d o n t h e o t h e r a s s u m p t i o n s , a s i m p l e ra p p r o a c h m a y b e s u ff i ci e n t. S u c h a n a p p r o a c h c o n s i d e r s o n l yr a d i a l ( a n d , e v e n t u a l l y, t a n g e n t i a l ) b e d d i n g , n e g l e c t i n g t h ei n t e r d e p e n d e n c e o f r a d i a l a n d t a n g e n t i a l d i s p l a c em e n t sa n db e d d i n g s . F o r n o n - c i r c u l a r c r o s s - s e c t i o n s , t h e c o n t i n u u ms o l u t i o n r e v e a ls t h a t b e d d i n g m a y b e in c r e a s e d a t c o r n e rs e c t io n s o f t h e l i n i n g , w i t h s m a l l e r r a d i u s o f t h e c u r v a t u r e .

T h e b e d d e d - b e a m m o d e l m a y b e a d j u s te d t o m o r e c o m p l e xc a s e s , e . g . b y r e d u c i n g t h e c r o w n l o a d i n a c c o r d a n c e w i t hs t ress re lease a t the tu nne l face (see F ig . 3 ) o r, fo r deep tu nne ls ,b y a s s u m i n g b e d d i n g a l s o a t t h e c ro w n .

F o r a r t i c u l a t e d e f f e c t i v e h i n g e s i n l i n i n g s t h e b e n d i n gm o m e n t s a r e s m a l l e r ; t h e d e f o r m a t i o n s m a y b e l a rg e r,d e p e n d i n g o n t h e g r o u n d s t i f f n e s s . F o r h i n g e d l i n i n g s t h el i m i t o f f l g i v e n a b o v e i s n o t v a l i d .

T h e a n a l y s is o f t h e b e d d e d b e a m y i el d s r i n g f o r ce s , b e n d i n gm o m e n t s , a n d d e f o r m a t i o n s a s d e s ig n c r i te r i a f o r t h e l in i n g . I ft h e l i n i n g r i n g i s c o m p l e t e l y c l o s e d , t h e b e n d i n g m o m e n t sm a y b e c o n s i d e r e d l e s s i m p o r t a n t t h a n t h e r i n g f o r c e s f o rp r o v i d i n g e q u i l i b r i u m ( a s m a l l e r s a fe t y f a c t o r m a y b e

Gv=~/'H ~u Gs-Kru N M

I --H =4 R t~ f .....-I.moxM

Gh= K o 'G ~ ] ~ Kr=const.

Gv radial ground ho op bending~=volum e w eigh t dis pl, reaction forces moments

F i g u r e 6 . E x a m p l e o I a b e d d e d - b e a m m o d e l [ o r s h a l l o wtunnels .

~ 1 ~ o s t r e s s r e | e o s e

~ w - - ~ - - - - - w A ~ - E :e q u i l i b r i u m a n d- w G , 4

c o n t i n u i t y

Figure 7 . Charac te r i s tic curves /or the groun d a nd the supp or t/ o r c o n v e rg e n c e - c o n f i n e m e n t m o d e l s ( F e n n e r- P a c h e r c u r v es ).

j u s ti f ie d f o r th e b e n d i n g m o m e n t s ) . A l l o w a n c e s a l s o m a y b em a d e f o r a p l a st i c r o t a t i o n c a p a c i t y o f th e l i n i n g s e g m e n t s .

F o r t u n n e l s w i t h v e r y p r o n o u n c e d s t re s s r e l ea s e d u e t oi n w a r d d e f o r m a t i o n s , e . g . f o r d e e p t u n n e l s i n r o c k , a s i m p l ea p p r o a c h t o d e si g n c o n s i d e r a t i o n s i s g iv e n b y t h ec o n v e r g e n c e - c o n f i n e m e n t m o d e l , w h i c h i s b a s e d o n l y o n t h ei n t e r a c ti o n o f t h e r ad i a l i n w a r d d i s p l a c e m e n t a n d t h e s u p p o r tr e a c t i o n t o th e s e d e f o r m a t i o n s b y r e s i s t i n g r i n g f o r c e s a n d t h ec o r r e s p o n d i n g o u t w a r d p r e s s u r e ( se e F i g . 7 ).

T h e p r i m a r y s t re s se s o0 i n t h e g r o u n d a r e r e le a s e d w i t hp r o g r e s si v e i n w a r d d i s p l a c e m e n t s . T h e a c t i n g p r es s u r e m a ye v e n i n cr e a se w h e n r o c k j o i n t s a r e o p e n i n g w i t h l a rg e rd i s p l a c e m e n t s . I n s e l f - s u p p o r t i n g r o c k , t h e g r o u n d c h a r -a c t e r i s t i c i n F i g . 7 m e e t s t h e w - a x i s ; b e c a u s e t h e p r i m a r ys t r e s s e s a r e r e l e a s e d c o m p l e t e l y, a s u p p o r t i n g l i n i n g i s n o tn e c e s sa r y. B e f o re t h e s u p p o r t i n g m e m b e r s a r e i n s t a ll e d , i t i su n a v o i d a b l e - - e v e n d e s i r a b l e - - t h a t d e c o m p r e s s i o n a ss o c ia t edw i t h t h e p r e d e f o r m a t i o n w 0 w i l l o c c u r. T h e s t if f n es s o f t h el i n i n g d e t e r m i n e s w h e r e b o t h c u r v e s ( c h a r a c t e r is t i c l in e s ) w i l li n t er s e ct . A t t h i s p o i n t , e q u i l i b r i u m a s w e ll a s c o m p a t i b i l i t yc o n d i t i o n s a r e f u l fi l le d . I f th e g r o u n d c h a r a c t e r i s t i c is k n o w n ,e .g . , by in -s i tu m o n i t o r i n g , t h e p r e d e f o r m a t i o n w 0 a n d t h es t i f f n e s s o f t h e l i n i n g ( i n c l u d i n g i t s d e v e l o p m e n t o v e r t i m ea n d a s t u n n e l l i n g a d v a n c e s ) , a n d e v e n i t s p l a s t i c p r o p e r t i e s

a re very dec i s ive fo r the ac tu a l s t resses in the l in ing . B othc u r v e s i n F i g . 7 m a y v a r y c o n s i d e r a b l y.

I n i t s u s u a l a n a l y t i c a l f o r m , t h e c o n v e rg e n c e - c o n f i n e m e n t• m o d e l a s s u m e s c o n s t a n t g r o u n d p r e ss u r e a l o n g a c i r c u l a r

t u n n e l l i n i n g . C o n s e q u e n t l y, i t y i e ld s o n l y r i n g f o r ce s a n d n ob e n d i n g m o m e n t s a t a l l. H o w e v e r , i t m a y b e ex t e n d e d t o co v e rg r o u n d p r e s su r e s t h a t v a r y a l o n g t h e tu n n e l l i n i n g ( G e st a1986).

T h e m o d e l m a y a l s o b e a p p l i e d a s a f ir s t a p p r o x i m a t i o n f o rn o n - c i r c u l a r t u n n e l c r o s s - s e c t i o n s , a l t h o u g h t h e s u p p o r treac t ion curve i s d i s t inc t ly d i ffe ren t , e .g . fo r horseshoe- typec r o s s s e c t i o n s . T h e r e f o r e , i t m a y b e h e l p f u l t o u s e t h ec o n v e r g e n c e - c o n f i n e m e n t m o d e l i n c o m b i n a t i o n w i t h ac o n t i n u u m m o d e l a n din-si tu m e a s u r e m e n t s .

A l t h o u g h t h e c o n v e r g en c e - c o n f in e m e n t a p p r o a c h isp r i m a r i l y a t o o l f o r th e i n t e r p r e t a t i o n o f f i e ld m e a s u r e m e n t s ,i t a l s o m a y b e a p p l i e d i n s u p p o r t o f t h e e m p i r i c a l a p p r o a c h .

4 . 4 . Empirical pproachT h e s t r u c tu r a l e l e m e n t s a n d t h e e x c a v a ti o n p r o c e d u r e ,

e s p e c i a l ly f o r t h e p r e l i m i n a r y s u p p o r t o f t h e t u n n e l , m a y b es e l e c t e d m a i n l y b a s e d o n e x p e r i e n c e a n d e m p i r i c a lc o n s i d e r a t i o n s t h a t r e l y m o r e o n d i r e c t o b s e r v a t i o n s t h a n o nn u m e r i c a l c a l c u l a t io n s . T h i s p r o c e d u r e m a y b e e s p ec i a ll yr e a s o n a b l e i f e x p e r i e n c e s f r o m a s u c c es s f u l t u n n e l l i n g p r o j e c tc a n b e a p p l i e d t o a s i m i l a r, n e w o n e y e t t o b e d e s i g n e d . S u c h at r a n s fe r o f i n f o r m a t i o n i s j u s t i f ie d o n l y w h e n :

• T h e g r o u n d c o n d i t io n s , i n c l u d i n g t h o s e o f t h e g r o u n dw a t e r, a r e c o m p a r a b l e .

• T h e d i m e n s i o n s o f t h e t u n n e l a n d i t s c r o s s - s e c t i o n a ls h a p e a r e s i m i l a r.• T h e d e p t h s o f o v e rb u r d e n a r e a p p r o x i m a t e l y t h e sa m e .

Vo lum e 3 , N um be r 3 , 1988 TUNNELLING AND UNDERGROUNDSPACE TECHNOLO GY 243


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• The tun nel li ng methods to be employed are the same.• In-s i tumon it ori ng yields resuhs compara ble to those for

the preceding tunn ell ing project.

One disadvantage of prolonged application of the empiricalapproach is that, lacking an incentive to apply a moreappropr iate tun nel li ng design via a consistent safetyassessment, the structure may be designed overconservatively,resulting in higher construction costs. Th e simple empiricalapproac h contribu tes little to the advance ment of the state ofthe art in tunnelli ng.

The empirical approach to tunnel design may also beapplied to larger projects in only slightly changin g ground ifprovision is made (especially in the tender) for initialexperiences to be extrapolated to the subsequent sectionsalong the tunnel axis. Such a situation justifies aineasu rement progr amme that is more intensive for the firstsections, in order to gain experience.

4 . 5 . O b s e r v a t i o n a l e t h o dBy combi ning analytical methods with the empirical

approach and the immediate interpretations of in-si tumeasurements, a tunn ell ing design procedure that isadjustable as the t unne l excavation proceeds may be applied.In this approach, the field measurements of groundmovements, displacement s and stresses in the l in ing are usedon an ongoing basis to verify or modify the design of thetunne l. More intensi vely inst rume nted sections at the earlystages of the tu nne lli ng provid e the data for these procedures.The inter pretat ion of the measured data yields insig ht intothe ground behaviour as a reaction to the tunnellingprocedure.

In applying the observational method, the followingcondi tions must be met:

• The chosen tu nnel ling process must be adjustable alongthe tunnel line.

• Owner and co ntractor mus t agree in advance oncontrac tual arrangem ents that allow for modifications ofthe design on an ong oin g basis duri ng the project.

• The field measurements should be interpreted on the

basis of a suitable analytical concept relatingmeasure ment data to design criteria.• The interpretation of a particular instrumente d section

must be used to draw conclusions about the othersections of the tunnel. Hence, the experiences arerestricted to those tunnel sections that are comparablewith respect to grou nd cond iti ons, gro und cover, etc. (seeSection 4.4 Empiri cal Approach ).

• Field measure ment should be provided thro ugho ut theentire len gth of the tun nel in order to check its assumedbehaviour.

4 . 6 . S p e c i a l D e s i g n F e a t u r e sSpecial considerat ions may be necessary if unus ual g rou nd

beha viou r is expected or is caused by gro und i mproveme nts.Some special design features and considerat ions are discussedbelow.

4 .6 .1 . Ground improvement t echn iquesG r o u t i n g a n d i n je c t io n s .Intensive grouti ng or injections

of the ground may improve the ground characteristicsconsidered in the design model. Although in most casesgrout ing is applied o nly for closing discontinuities in rock orfor streng then ing soft ground , i n both cases the goal is toachieve better homogenei ty.

Drainage and compressed a i r.Usually the ground isstabilized by dewateri ng it and by avo idin g inflows of water.Ground failure may be avoided if the pore water pressure isminimized. The assumed ground characteristics may be validonly if successful drainage is possible or if water inflow isprevented, as in t unn ell ing under compressed air.

( ; round [ reez ing . iin prov ing the ground by hcezin~changes the ground properties. The time-dependenl sucss-strain beha viour of frozen grou nd can be significant. Freezingdraws water toward the li ning , causing an increase in watelvolume an d heave at the surface. Concret ing on frozen grounddelays the strength development of the concret<

4.6.2 . Unusual ground behaviour

S w e l l i n g g r o u n d .Stress release due to t unn el li ng and /o rground water infl ux may cause swelling and a correspondingincrease in pressure on the lining. In these cases, a circularcross-section or at least an invert arch is recommended. Th eswelling result ing from a chemical reaction, as in anhydrid,generally is much more pronounced than that due to thephysical absorption of water, as ill clay.

U n d e rg r o u n d e r o si o n , m i n i n g s u b s id e n c e , a n d s i n k h o le s .Tu nn el li ng in ground that is subject to settlements, as in thecase of gypsum erosion or m in in g subsidence, requires specialdesign considerations. A flexible lining that follows theground movements by utilizing its plastic deformationcapacity is more suitable in these cases than is a too-rigid orbrittle, failure-prone lining. If the ground has sinkholepotentials, a tunn el structure that can be repaired easily maybe more economical than a structure designed to allow thebrid ging of the sinkholes.

5 . I n S i t u M o n i t o r i n g5.1. Purpose o fI n S i t u e a s u r e m e n t s

l n - s i t u moni tori ng during the excavation and at longerintervals after the tunne l is completed should be regarded asan integral part of the design not only for checking thestructural safety and the applied design model but also forverifying the basic conception of the response of the groun d totun nel li ng and the effectiveness of the structural support.

The mai n objectives of in-si tu monit oring are:(1) To control the deformations of the tunnel, including

securing the open tunnel profile. The time-history

development of displacements and convergences may beconsidered one safety criterion, alt houg h field measurementsdo not yield the margins the structure can endure beforefailing.

(2) To verify that the appropria te t un nel li ng method wasselected.

(3) To c ontro l the settlem ents at the surface, e.g. in order toobtain inf ormati on on the deformation pattern in the groundand o n that part of settlements caused by lowering the waterlevel.

(4) To measur e the deve lop ment of stresses in the struc turalmembers, in dic ati ng sufficient strength or the possibility ofstrength failure.

(5) To indicate progressive deformations, which requireimmediate action for ground and support strengthening.

(6) To furnish evidence for insurance claims, e.g. byprovi ding results of levelli ng the settlements at the surface intown areas.

5 .2 . M o n i t o r i n g M e t h o d sA progra mme for monit ori ng the deformatio ns and stresses

during the excavation may comprise the followingmeas urem ents (see Fig. 8):

(1) Levelling the crown (at the least) inside the tunnel assoon as possible. With regard to interpretation of the data,Fig. 2 reveals that often only a small fraction of the entirecrown movement can be monitored because a larger partoccurs before the bolt can be set. For difficult t unne lli ng, thedistance between two crown readings may be as close as 10-

15 m. Leve lling of the i nvert is recommende d for rock havi ngswelling potentials.(2) Convergence readings (in t riang ular settings; K in Fig.

244 TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY Vo lu me 3, Nu mb er 3, 1988


9/13


10/13

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G e r m a n y.

246 TUNNEL LING AND UNDERGROUND SPACE TECHNOLOGY Vo l u m e 3 , N u m b e r 3 , 1 9 8 8


11/13

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Vo lu me 3, Nu mb er 3, 1988 TUNNELL ING AND UNDERGROUND SPACE TECHNOLOGY 247


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7 . E x ampl e s o f P r e sen t at ionof Tunnel D es ign Data

F i g u r e s 9 - 1 2 a re n a t i o n a l e x a m p l e s o f t a b u l a t e di n f o r m a t i o n o n g e o t e c h n i c a l c o n d i t i o n s a n d d e s i g nc h a r a c te r i st i c s g i v e n i n c o n d e n s e d f o r m a l o n g a l o n g i t u d i n a lt u n n e l s e c ti o n . T h i s i n f o r m a t i o n m a y b e p a r t o f t h e te n d e r i n gd o c u m e n t s a n d s h o u l d b e a m e n d e d w i t h o n g o i n g t u n n e l li n g .B y g a t h e r i n g t h e d a t a a c t u a ll y e n c o u n t e r e d a l o n g t h e tu n n e ll i n e in a s i m i l a r t a b le , a c o m p a r i s o n c a n b e m a d e b e t w e e np r e d i c t e d a n d a c t u a l t u n n e l l i n g c o n d i t i o n s . [ ]

Braunschweig, West Germany: Ber ichte lns l i tu t tuJ Sta l ik .Techn ica l Un ive r s i ty o f Braunschwe ig .

C,es ta , P. 1986. Rec om me nda t ions Iol use ot t i le conw~rgl 'm¢' -conf inemen t me thod .Tu n n e l s O u v r a g e s S o u t e r r a i n s73: 18-39.

In t e rna t iona l Soc ie ty o f Rock Mechan ic s Comm iss ion onClass i f ica t ion of Rocks and R ock Masses . 1981.ln t . ] . t lockM e c h a n i c s M i n i n g S c i .18:85-110.

In t e rna t iona l Soc ie ty o f Rock Mechan ic s . 1975 . ISRM Recom mend a-t ions on s i te invest igat ion techniques .

In t e rna t iona l Tu nne l l i ng Assoc ia t ion Wo rk ing Group on S t ruc tu ra lDesign of Tun nels . 1982.A d v a n c e s Tu n n e l l . Te c h n o l . S u b s u r [ a c eUse 2(3): 153-228.

Refe r en c e sErdman n , J . 1983. Com par i son o f two-d imens iona l and deve lopm en t

o f t h ree -d imens iona l des ign me thods fo r t unne l s ( i n German) .

N o t eISee, for example , t i le Swiss SIA Do kum ent 260 or the corresp ondin gU.S.-ASCE Code.

Appendix . nternational and National Recommendations on Structural Design o/T un nel s.

I S R M r e c o m m e n d a t i o n s o n s it e i n v e s t ig a t i o n t e c h n i q u e s ,J u l y 1 9 7 5 .

D o c u m e n t N o . 2 - - S u g g e s t e d M e t h o d s fo r R o c k B o lt Te s d n g

A u s t r a l i a

A u s ~ i a

Aus t ra l i an S tandard 1726 - S .A.A. S i t e Inves t iga t ion Code .

A u s t r a l i an S t a n d a r d 1 2 8 9 - M e t h o d s o / Te s t i n g S o i l s [ o r E n g i n e e r i n g P u r p o s e s .

France T t m n el s a O ~ g e s S l a e d a l I u u e ~ J t a h t l ~ , p p . $ 2 - 1 2 ~ :

9 4 8 T U N N E L L I N G A N D U N D E R G R O U N D S PA C E T E C H N O L O G Y V o l u m e 3 , N u m b e r 3 , 1 9 88


13/13

Pr6 ~zntation de la m&hode de construction des tunnel avec sout~nement

JapanTunnel Engineering Committee,Japan Society of Civil Engineering,Japan Tunnelling Association

Switzerland

United Kingdom

Recommandat ions sur les conditions d'emplo i du boul onnage (Recommenda-tions for conditions of the use of bolting).

Tunnels et Ouvrages Souterrains 73 ( J a n . / F e b . 1 9 8 6 ), p p . 1 8 - 3 8 :Recommendations for use of the convergence-confinement method.

Tunnels et Ouvrages Souterrains 67 (Jan./Feb. 1985) , pp. 32-43:Reco mman dati ons relatives au choi x d'un type de sout~nement en galerie(Recommendations for the selection of tunnel support).

Tunne ls et Ouvrages (1984), pp. 80-97: Recommand atio ns relatives ~ l'empl oides citres dans la construction des ouvrages souterrains (Recommendations onthe use of steel arches as temporar y sup port in tunnel structures).

Standard Specifications for Tunnel s:

Mountain Tunnelling Method. Nov. 1986.

Shield Tun nel lin g Method. Jun e 1986.

Cut-and-cover Method. Ju ne 1986.

Recomma ndatio n SIA No. 199: Etude du massif rocheux po ur les travauxsouterrains. 1975. (Also in Germa n)

Norm e SIA No. 198: Tra vaux souterrains (avancement ~ l'explosif). 1975. (Alsoin German)

Recommandation SIA No. 198/1: Construction de tunnels et de galeries e nrocher au moyen de tunneliers. 1985. (Also in Ger man)

British S tandar d 1377. Methods of test for soils for civil engineerin g purposes,British Standards Institution, 1975.

British S tandard 5930, Code of Practice for site investigati ons, British S tandardsInstitution, 1981.

Craig, R. N. and Mu ir Wood, A. M. A review of tunnel l ining practice in theUnited Kingdom. T RR L Supplementary Report 335, 1978.

Tunne lli ng Waterproofing. CI RIA Report 81, 1979.

Dumbleton, M .tunnels. TRRL

Vol ume 3, Number 3, 1988 TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 249

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Tunnel Design Guidelines Paper