Quantitative Verification of Some Standard Support Patterns in Japanese Tunneling Design Standards
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Rock bolting effect of standard support patterns of Japan Road Association, Japan Highway Public Corporation and Japanese National Railways in various ground conditions are analyzed quantitatively based on the interaction model of rock bolt and rock mass. Shortcrete plays an important effect in the reinforcing system and it works together with rock bolt. Rock bolting effect is improved by thicker shotcrete application in poor ground conditions but its effect is not significant in good ground condition. Rock bolt reinforcement is influenced by the shotcrete and the ground competency factor. Comparisons of the results show that the different standard support patterns do not vary significantly except some differences in rock bolt density parameters and its length. Support performances of all the standard support patterns show the agreement with design recommendation.
Quantitative Verification of Some Standard Support Patterns in Japanese Tunneling Design Standards
- 1. AA QQuuaannttiittaattiivvee VVeerriiffiiccaattiioonn ooff SSoommee SSttaannddaarrdd SSuuppppoorrtt PPaatttteerrnnss iinn JJaappaanneessee TTuunnnneelliinngg DDeessiiggnn SSttaannddaarrddss 22000055 DDeeppaarrttmmeenntt ooff CCiivviill aanndd SSttrruuccttuurraall EEnnggiinneeeerriinngg KKyyuusshhuu UUnniivveerrssiittyy,, FFuukkuuookkaa,, JJaappaann 九州大学大学院工学府 建設システム工学専攻 SSOONNYYOOKK DDEESSHH RRAAJJ
- 2. BBBBaaaacccckkkkggggrrrroooouuuunnnndddd aaaannnndddd PPPPuuuurrrrppppoooosssseeee BBaacckkggrroouunndd TTuunnnneelliinngg ddeessiiggnn iiss ssttiillll eemmppiirriiccaall oorr sseemmii-eemmppiirriiccaall. RReeiinnffoorrcciinngg eeffffeecctt ooff ssttaannddaarrdd ppaatttteerrnn iiss nnoott cclleeaarr. QQuuaannttiittaattiivvee aapppprrooaacchh ffoorr ddeessiiggnn mmooddiiffiiccaattiioonn PPuurrppoossee QQuuaannttiittaattiivvee vveerriiffiiccaattiioonn ooff ssuuppppoorrttiinngg eeffffeecctt:: ((1)) JJaappaann RRooaadd AAssssoocciiaattiioonn ((22)) JJaappaann HHiigghhwwaayy PPuubblliicc CCoorrppoorraattiioonn ((33)) JJaappaanneessee NNaattiioonnaall RRaaiillwwaayyss.
- 3. TThheeoorreettiiccaall bbaassiiss ooff tthhiiss ssttuuddyy QQuuaannttiittaattiivvee aannaallyyssiiss ooff tthhee ssttaannddaarrdd ssuuppppoorrtt ppaatttteerrnnss SSttuuddyy ppaarraammeetteerrss aanndd aassssuummppttiioonnss RReessuullttss CCoonncclluussiioonnss FFuuttuurree ssttuuddyy CCCCoooonnnntttteeeennnnttttssss
- 4. TTTThhhheeeeoooorrrreeeettttiiiiccccaaaallll bbbbaaaassssiiiissss ooooffff tttthhhheeee ssssttttuuuuddddyyyy EEllaassttiicc-ppllaassttiicc aannaallyyssiiss ((MMoohhrr-CCoouulloommbb tthheeoorryy)) SSttrraaiinn ssoofftteenn mmooddeell,, ddiillaattiioonn IInntteerraaccttiioonn bbeehhaavviioorr ooff rroocckk mmaassss aanndd rroocckk bboolltt:: ((CCoouupplliinngg aanndd ddeeccoouupplliinngg bbeehhaavviioorr)) w o symmetric O ra Rf Re Po Lz LT LT r L1 Plastic flow zone Soften zone Elastic zone r g r o u n d d i s t r i b u t i o n o f a x i a l f o r c e t u n n e l P m a x o p e n i n g r o c k b o l t Neutral point
- 5. Ranges of RRRaaannngggeeesss ooofff ddddeeeeffffoooorrrrmmmmaaaattttiiiioooonnnn mmmmoooodddduuuulllluuuussss Japan J apa n Ro Road ad As s o c ia Association t io n classes mass Japan J apa nHighway Highway Pu blic Co rpo P. ra t io n Corp. Rock Japanese J apa n e s e National Na t io n a l Ra ilways Railways 0 1000 2000 3000 Deformation modulus (MPa) 500 1000 1500 2000 2500 3000 B CI CII DI DII B CI CII DI DII III N II N I N I S I L Ro c k ma s s c la s s De f o rma t io n mo du lu s Em (GPa )
- 6. Study parameters SSStttuuudddyyy pppaaarrraaammmeeettteeerrrsss aaaannnndddd ccccaaaasssseeee aaaarrrrrrrraaaannnnggggeeeemmmmeeeennnnttttssss β= 0 ～ 1.0 Em = deformation modulus of rock mass σc = axial strength Srp = Competency factor (=σc/γH) γ = density of rock H = overburden depth β = rock bolt density parameter (1 = 50×50 cm) Em=200σc Srp = 0.1 ～ 2.0 2 / b a z t b = p r l r L L ra=tunnel radius, rb=radius of rock bolt , λ is friction coefficient Lz and Lt are rock bolt spacing.
- 7. Study Parameters o SSStttuuudddyyy PPPaaarrraaammmeeettteeerrrsss oooffff JJJJaaaappppaaaannnn RRRRooooaaaadddd AAAAssssssssoooocccciiiiaaaattttiiiioooonnnn (a) Tunnel radius = 6.25 m ( 4.25 ~ 6.25 m) Support pattern no t'c (m) L β z L (m) t Support L (m) (m) class Rock class B B 3 1.5 2 0.094 0.05 JA1-Pt1 C 3 1.5 1.5 0.128 0.1 JA1-Pt2 I CI C 3 1.5 1.2 0.16 0.1 JA1-Pt3 II ーa CII C 3 1.5 1.2 0.16 0.15 JA1-Pt4 II-b D 3 1.2 1 0.236 0.21 JA1-Pt5 I-a DI D 4 1.2 1 0.21 JA1-Pt6 I-b D 4 1.2 <1.0 >0.236 >0.28 JA1-Pt7 II DII
- 8. Study Parameters SSStttuuudddyyy PPPaaarrraaammmeeettteeerrrsss ooooffff JJJJaaaappppaaaannnn HHHHiiiigggghhhhwwwwaaaayyyy PPPP.... CCCCoooorrrrpppp.... Tunnel radius = 5.1 m Support pattern no t'c β (m) Lz (m) Lt Support L (m) (m) class Rock class B B-a 3 1.5 2 0.094 0.05 JH-Pt1 C 3 1.5 1.5 0.128 0.1 JH-Pt2 I CI C 3 1.5 1.2 0.16 0.1 JH-Pt3 II ーa CII C 3 1.2 1.2 0.2 0.15 JH-Pt4 II-b D 3 1.2 1 0.24 0.21 JH-Pt5 I-a DI D 4 1.2 1 0.24 0.21 JH-Pt6 I-b D 4 1.2 <1.0 >0.24 >0.28 JH-Pt7 II DII
- 9. Study Parameters SSStttuuudddyyy PPPaaarrraaammmeeettteeerrrsss ooooffff JJJJaaaappppaaaannnn NNNNaaaattttiiiioooonnnnaaaallll RRRRaaaaiiiillllwwwwaaaayyyyssss Support pattern no t'c L β (m) z L (m) t Support L (m) (m) class III 2 3.9 1.5 0.052 0.1 JR1-Pt1 N II 3 3 1.5 0.068 0.1 JR1-Pt2 N I 3 1.9 1 0.163 0.21 JR1-Pt3 N I 3 1.2 1 0.258 0.25 JR1-Pt4 S I 4 1.2 1 0.258 0.25 JR1-Pt5 S I 3 2.3 1 0.134 0.28 JR1-Pt6 L III 2 3 1.5 0.068 0.1 JR2-Pt1 N II 3 2.3 1.5 0.089 0.1 JR2-Pt2 N I 3 1.6 1 0.193 0.21 JR2-Pt3 N I 3 1.1 1 0.281 0.25 JR2-Pt4 S I 4 1.1 1 0.281 0.25 JR2-Pt5 S I 3 1.9 1 0.163 0.28 JR2-Pt6 L
- 10. IIIInnnnfffflllluuuueeeennnncccceeee ooooffff sssshhhhoooottttccccrrrreeeetttteeee tttthhhhiiiicccckkkknnnneeeessssssss JA1-Pt1: t'c = 0.05 m and L=3.0 m JA1-Pt2: t'c = 0.1 m and L=3.0 m 0.25 0.2 0.15 0.1 0.05 0 0 0.2 0.4 0.6 0.8 1 De s ns it y o f ro c k bo lt β St ra in (Ura/ ra ) Srp=0.1 Srp=0.1~1.2 0.25 0.2 0.15 0.1 0.05 0 0 0.2 0.4 0.6 0.8 1 De s n s it y o f ro c k bo lt (β ) St ra in (Ura/ ra ) Srp=0.1 Srp=0.1~1.2
- 11. IIIInnnnfffflllluuuueeeennnncccceeee ooooffff RRRRoooocccckkkk bbbboooolllltttt lllleeeennnnggggtttthhhh JA1-Pt5: rraa ==66..2255 mm, tt''cc == 00..2211 mm and LL==33..00 mm Em=0~600 MPa JA1-Pt6: rraa ==66..2255 mm,, tt''cc == 00..2211 mm and LL==44..00 mm 0.1 0.08 0.06 0.04 0.02 0.1 0.08 0.06 0.04 0.02 0 0 0.2 0.4 0.6 0.8 1 De n s it y o f ro c k bo lt β St ra in Ura/ ra Srp=0.1 Srp=0.1~1.2 0 0 0.2 0.4 0.6 0.8 1 De n s it y o f ro c k bo lt β St ra in Ura/ ra 00..2244 Srp=0.1 Srp=0.1~1.2
- 12. Comparison of tunnel CCCooommmpppaaarrriiisssooonnn ooofff tttuuunnnnnneeelll wwwwaaaallllllll ddddiiiissssppppllllaaaacccceeeemmmmeeeennnntttt 350 300 250 200 150 100 50 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 .1 1.2 Comp e t e nc y fa c t or (Srp ) Dis p la c e me nt (c m) St an da rd Su ppo rt (J A1 - Pt7) No s uppo rt 50 45 Dis pa lc e me nt (c m) St an da rd Su ppo rt (J A1 - Pt7) 40 35 30 25 20 15 10 5 0 Sh o rt c re t e o n ly 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 .1 1 .2 Comp e t e nc y fa c to r (Srp) DDiissppllaacceemmeenntt rreessttrraaiinneedd bbyy rroocckk bboolltt
- 13. IIIInnnnfffflllluuuueeeennnncccceeee ooooffff RRRRoooocccckkkk bbbboooolllltttt lllleeeennnnggggtttthhhh JH-Pt5: rraa ==55..11 mm, tt''cc == 00..2211 mm and LL==33..00 mm JH-Pt6: rraa ==55..11 mm, tt''cc == 00..2211 mm and LL==44..00 mm 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Srp=0.1 0 0.2 0.4 0.6 0.8 1 De ns ity o f roc k bo lt β St ra in (Ura/ ra ) 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0 0.2 0.4 0.6 0.8 1 De ns ity of ro c k bo lt β St ra in (Ura/ ra ) Srp=0.2 Srp=0.1 Srp=0.2 Srp=0.1~1.2 Srp=0.1~1.2
- 14. Comparison of CCCooommmpppaaarrriiisssooonnn ooofff DDDDiiiiffffffffeeeerrrreeeennnntttt SSSSttttaaaannnnddddaaaarrrrdddd SSSSuuuuppppppppoooorrrrttttssss Em (MPa) t'c (m) Length of rock bolt 2 m 3 m 4 m 6 m 600 ~ 3000 0.05 JA1-Pt1 (B) 600 ~ 1200 JH-Pt1 (B) 600 ~ 3000 0.1 JA2-Pt1 (B) 300 ~ 1200 80 ~ 1200 JR1-Pt1 (IIIN) JR2-Pt1 (IIIN) JA1-Pt2 (CI) JA1-Pt3 (CII) 80 ~ 600 JH-Pt2 (CI) JH-Pt3 (CII) JR1-Pt2 (IIN) JR2-Pt2 (IIN) 300 ~ 1200 0.15 JA2-Pt2 (CI) 80 ~ 1200 JA1-Pt4 (CII) 80 ~ 600 JH-Pt4 (CII)
- 15. Continued….. 20 ~ 600 0.21 JA1-Pt5 (DI) JA1-Pt6 (DI) 80 ~ 300 JH-Pt5 (DI) 80 ~ 1200 JA2-Pt3 (CII) 80 ~ 300 JR1-Pt3 (IN) JR2-Pt3 (IN) JH-Pt6 (DI) 80 ~ 300 0.25 JR1-Pt4 (IS) JR2-Pt4 (IS) JR1-Pt5 (IS) JR2-Pt5 (IS) 0~ 600 0.28 JA2-Pt4 (DI) 0~ 300 JR1-Pt6 (IL) JR2-Pt6 (IL) JA1-Pt7 (DII) JH-Pt7 (DII) 0~ 600 0.38 JA2-Pt5 (DII)
- 16. Comparison CCCooommmpppaaarrriiisssooonnn ooooffff ssssuuuuppppppppoooorrrrttttiiiinnnngggg eeeeffffffffeeeeccccttttssss JA1-Pt2 & JH-Pt2, β=0.13 JA1-Pt3 & JH-Pt3, β=0.16 JR1-Pt2, β=0.07 JR2-Pt2, β=0.09 Srp=0.6 Srp=0.4 Srp=1.2 Srp=0.8
- 17. Comparison CCCooommmpppaaarrriiisssooonnn ooooffff ssssuuuuppppppppoooorrrrttttiiiinnnngggg eeeeffffffffeeeeccccttttssss JA1-Pt5 &JH-Pt5, β=0.24 JR1-Pt3, β=0.16 JR2-Pt3, β=0.19 Srp=0.4 Srp=0.6 Srp=0.8 Srp=1.2
- 18. CCCCoooonnnncccclllluuuussssiiiioooonnnn ((((1111)))) Shortcrete ppllaayyss aann iimmppoorrttaanntt eeffffeecctt iinn tthhee rreeiinnffoorrcciinngg ssyysstteemm.. − IImmpprroovveemmeenntt ooff rroocckk bboollttiinngg eeffffeecctt ((SSrrpp<<00..44)) − NNoo ssiiggnniiffiiccaanntt iimmpprroovveemmeenntt ((SSrrpp>>00..88)) RRoocckk bboolltt lleennggtthh:: − uupp ttoo 66 mm,, iinnccrreeaasseess tthhee rroocckk bboollttiinngg eeffffeecctt iinn wweeaakk rroocckk mmaasssseess wwhheenn rraa==66..2255~~77 mm.. − nnoo ddiiffffeerreennccee iiss sseeeenn wwhheenn tthhee rroocckk bboolltt iiss lloonnggeerr tthhaann 33 mm ffoorr mmeeddiiuumm ssiizzee ttuunnnneell wwhheenn rraa==55..11 mm..
- 19. CCCCoooonnnncccclllluuuussssiiiioooonnnn ((((2222)))) Supporting patterns ooff JJHH iiss aallmmoosstt ssiimmiillaarr ttoo tthhaatt ooff JJRRAA.. IInn aa ggoooodd ggrroouunndd ccoonnddiittiioonn,, rroocckk bboolltt ddeennssiittyy ooff JJRR iiss ssmmaalllleerr tthhaann tthhaatt ooff JJHH//JJRRAA.. HHoowweevveerr,, tthheerree iiss nnoo ssiiggnniiffiiccaanntt ddiiffffeerreennccee ooff tthhee rroocckk bboollttiinngg eeffffeecctt.. IInn aa wweeaakk ggrroouunndd ccoonnddiittiioonn,, rroocckk bboolltt ddeennssiittyy ooff JJRR iiss llaarrggeerr tthhaann tthhaatt ooff JJHH//JJRRAA.. RReeiinnffoorrcciinngg eeffffeecctt ooff tthhee ppaatttteerrnn ooff JJRR iiss aa lliittttllee bbeetttteerr tthhaann tthhaatt ooff JJHH..
- 20. FFFFuuuuttttuuuurrrreeee ssssttttuuuuddddyyyy • Comprehensive verification with measured in-situ data • Consider gravity effect and try to include influence of in-situ stress ratio. • Study on shallow depth tunnel
- 21. TTHHAANNKK YYOOUU FFOORR YYOOUURR AATTTTEENNTTIIOONN
Editor's Notes
- #17: (JA1-Pt2 & JH-Pt2 = 300 ~ 1200 and 80 ~ 600 MPa ) ( JA1-Pt2 & JH-Pt3 = 80 ~ 1200 and 80 ~ 600 MPa ) (JR1-Pt2 & JR2-Pt2 = 80 ~ 600 MPa)
- #18: JA1-Pt5 &JH-Pt5 = 20 ~ 600 and 80 ~ 300 MPa JR1&2-Pt3 = 80 ~300 MPa
- #19: Shortcrete works together with rock bolt, and it plays an important effect in the reinforcing system. Rock bolt effect is significantly improved by shotcrete application in poor ground conditions (Srp&lt;0.4) but its effect is not significant when Srp&gt;0.8. Increase in rock bolt length up to 6 m, increases the rock bolting effect in weak rock masses when the tunnel radius is large (ra=6.25~7 m) but no difference is seen when the rock bolt is longer than 3 m for medium size tunnel (ra=5.1 m). Performance of different standard support patterns of JRA, JH and JNR do not vary significantly. Supporting patterns of JH is almost similar to that of JRA In a good ground condition, rock bolt density of JR is smaller than that of JH. However there is no significant difference of their reinforcing effect. In a weak ground condition, rock bolt density of JR is larger than that of JH. The reinforcing effect of the pattern of JR is a little better than that of JH.