urban soft ground tunnelling - hoixaydunghcm.vn soft ground... · • tunnelling at shallow depth...
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Introduction to Soft Ground Introduction to Soft Ground Introduction to Soft Ground Introduction to Soft Ground Tunnelling in Urban Tunnelling in Urban
EnvironmentEnvironmentDr. Noppadol PhienwejDr. Noppadol Phienwej
Geotechnical and GeoGeotechnical and Geo--environmental Engineeringenvironmental EngineeringSchool of Engineering and TechnologySchool of Engineering and Technology
Asian Institute of TechnologyAsian Institute of Technologygygy
ITA Wh T l?ITA- Why Tunnel?• A country’s infrastructure is one of its main assets• A country s infrastructure is one of its main assets• Developed countries require a modern infrastructure
• Roadsil• Railways
• Power• Communications• Water• Wastewater• Gas• Gas
• Congestion above and at surface level in urban metropolis, where space is at a premium, means
i d h d i h l i bl igoing under the ground is the only viable option
Infrastructures in Modern Urban Area
Underground Space Utilization in Urban Business Area
For Better Environment
Characteristics and Constraints of Characteristics and Constraints of Urban Tunnelling
• Tunnelling at shallow depth – Mostly soft ground tunnelling• High risk due to soft ground and groundwater
Construction in congestion area Traffic disturbance• Construction in congestion area – Traffic disturbance• Tunnelling at close proximity to existing buildings and
utilities- space constraints• Need to minimize damages to existing structures and third
parties• Need to control minimize movementsNeed to control minimize movements• Many parties involving- Work coordination
TUNNEL GROUNDS
•• ROCK TUNNELROCK TUNNEL
•• SOFT GROUND TUNNELSOFT GROUND TUNNEL
Rock Tunnelling
Rock Tunnelling
Rock Tunnelling – Investigation, Design & Construction
W EW E Geotechnical Longitudinal Section
-0,40
-0,30GG+
F
0 0 0 0 0 0 0 0 0 0 0
-0,20
-0,10
0,00
EDCBA
1150
1170
1190
1210
1230
1250
1270
1290
1310
1330
1350
Station [m]
Egnatia Motorway, Anilio Tunnel (Greece)
Rock Tunnel Excavation
Drill & BlastDrill & Blast
Rock Tunnel Boring Machine
Rock Tunnel Boring Machine
Soft Ground Tunnelling
Soft Ground TunnellingWhat is soft ground?
gg
Soft ground consists of various mixtures of sand, silt d land clay.
It can be described as firm raveling squeezing runningIt can be described as firm, raveling, squeezing, running flowing or swelling.
In all types of tunnelling, face stability is the primary goal, this is followed by ground movement controlcontrol.
Ground Movement
Soft Ground TunnellingGround Movement
Face StabilityFace Stability
Tunnel Collapse
M4 metroline crossing Huangpu River in Shanghai
Methods of Tunnel Methods of Tunnel Construction in Soft Ground
• Cut & Cover Construction• Tunnelling
–Shield Tunnellingg–Non-Shield Tunnelling – Shotcrete &
steel arch• Pipe Jacking (Micro Tunnelling)
Methods of Tunnel C t ti i S ft G dConstruction in Soft Ground
Cut and Cover for MRT
Singapore Hong Kong
Stuttgart, Germany
CUT AND COVER TUNNELCUT AND COVER TUNNEL
DIAPHRAGM WALLDIAPHRAGM WALLDIAPHRAGM WALLDIAPHRAGM WALL
BANGKOK MRT
PILE SUPPORTED STRUCTURE
SHIELD SHIELD TUNNELINGTUNNELING
Shield TunnellingShield Tunnelling
Shield TunnellingShield Tunnelling
Reinforced Concrete Segmental Lining
RC S t l RiRC Segmental Rings
Pipe Jacking (Micro Tunnelling)Pipe Jacking (Micro Tunnelling)
Thrust Shaft
S Control Container
Lubricant Preparation Plant
Th t W llITE
Control Container Thrust Wall
Jacking
LAYO
gPipeEntrance Ring
(Soft Eye)
OUTE Base SlabE
Jacking FrameTBM
PPIPEJJACKING
TBM and first pipe placed on jacking frame and ready to commence excavation through the soft eye
PPIPEJJACKING
TBM commences excavation and both pipe and machine togetherboth, pipe and machine together are pushed through the soft eye into the ground by the jacking cylinders
PPIPEJJACKING
Excavation is stopped, jacking pp , j gcylinders are moved backward so that the next pipe can be placed behind the string
PPIPEJJACKING
Then the jacking cylinders are again
d ti htl i tpressed tightly against the pipe end, ready to push the whole line forward
PPIPEJJACKING
PPIPEJJACKING
PPIPEJJACKING
PPIPEJJACKING
Jacking Operation - EPB 1500, 2600 and AVN 1200
PPIPEJJACKING
Shields for Pipe JackingShields for Pipe Jacking
World Record Breaking Pipe Jacking World Record Breaking Pipe Jacking Works in BangkokWorks in Bangkokgg
Shield TunnellingShield TunnellingShield TunnellingShield Tunnelling
Shield TypesShield Types
Slurry ShieldSlurry Shield
EPB Shield
General arrangement – EPB Shield Machine
Non-Shield TunnellingC ti l M th dConventional Method
Non-Shield Tunnelling
Shotcrete + Steel latticeSoil ImprovementSoil Improvement
NATM
FIRST ROAD TUNNELFIRST ROAD TUNNEL
BETONG YALABETONG, YALA
TUNNEL WITH SHOTCRETE AND STEEL ARCH
Invert Shotcreting
SEQUENTIAL EXCAVATIONSEQUENTIAL EXCAVATION
SEQUENTIAL EXCAVATIONSEQUENTIAL EXCAVATION
UNSTABLE GROUND
ROOF SPILINGROOF SPILING
FOREPOLING
When there are stability problem of ground
Umbrella Roof Method
PIPE JACKED ROOFPIPE JACKED ROOF
Freezing method was used to remove the old structure and build new structureand build new structure
Freezing pipes needed toneeded to freeze the ground under the pre-
Old structure
the preexisting tunnel. It could not be installed from
New structurethe road.
Therefore, the curve boring
Extent of frozen
curve boring method was adopted.
ground
INTERVENTION SHAFT EXCAVATION
Soft Clay
Stiff Clay
Sand
TUNNEL PORTALS AND SHAFTS
TUNNEL PORTAL TUNNEL PORTAL –– Slope StabilitySlope Stability
Permanent Shaft Sinking
Completed Shaft from tunnel level
Irregular Shape Shaft
TUNNEL SUPPORTTUNNEL SUPPORT
Cross section showing primary and secondaryCross section showing primary and secondary lining, after Hughes (1987)
DESIGN PRINCIPLESPRIMARY LINING OF SHOTCRETE INSTALLED CLOSE BEHIND
FACE AS EXCAVATION PROCEEDS TO MINIMISE GROUND RELAXATIONRELAXATION
•thin shell design approach ( limited moment capacity)
•applied loads less than full overburden due to negative pore pressure leading to arching support
•time dependent build up of loads
•allow for stress concentrations from nearby tunnels
•limited duration of use before secondary lining cast
includes load factor of 1 4•includes load factor of 1.4
•structural analysis using bedded beam model
Installed Segmented Rings Behind Shield Tail Skin
Segmental Lining
Primary Grouting After Segment Erection
Cement / Bentonite
Sodium Silicate
Grouting Material gels within 8 Sec.
Ring Deformation+Pressure
OBSTRUCTIONOBSTRUCTION
Difficulties in Tunnelling and Effects on Building Foundation
BUILDING PROTECTION PRINCIPLESBUILDING PROTECTION PRINCIPLESBUILDING PROTECTION PRINCIPLESBUILDING PROTECTION PRINCIPLES
DESIGN & CONSTRUCTION METHODSDESIGN & CONSTRUCTION METHODS DESIGN & CONSTRUCTION METHODS DESIGN & CONSTRUCTION METHODS TO MINIMISE GROUND MOVEMENTS TO MINIMISE GROUND MOVEMENTS PREDICTION OF MOVEMENTS REQUIREDPREDICTION OF MOVEMENTS REQUIRED BUILDING CONDITION SURVEYBUILDING CONDITION SURVEY 22nd & nd & 33rd STAGE ASSESSMENT IF REQUIREDrd STAGE ASSESSMENT IF REQUIRED ALERT LEVELS IDENTIFIED BEFOREHANDALERT LEVELS IDENTIFIED BEFOREHAND BUILDING PROTECTION IF REQUIREDBUILDING PROTECTION IF REQUIRED
INSTRUMENTATION & MONITORINGINSTRUMENTATION & MONITORING INSTRUMENTATION & MONITORINGINSTRUMENTATION & MONITORING
BUILDING DAMAGEBUILDING DAMAGE
Building response to ground movement
6.3 m outer-diameterSingle TrackSingle Track
TUNNEL–PILE RELATIVE POSITIONSUMMARYSUMMARY
Angel Underground Station, LondonExisting MRT North-East Line C704, Singapore
MTR Island Line, Hong KongMRTA Subway, BangkokElectric Power Tunnel, Japan
Existing super-
structure
Type 1
Tunnel45o
Type 2
MRT Circle Line C825, SingaporeC bl T l L dType
3Type
4
Tokyo Subway Line 7, JapanJ bil Li E t i L d
North/South Metroline, Amsterdam
Cable Tunnel, London
Jubilee Line Extension, LondonChannel Tunnel Rail Link 2, LondonMRT Circle Line C825, Singapore
TUNNELLING NEAR TO PILE FOUNDATION
Columns
BuildingNegative skin friction (NSF)
Downdrag
Pile cap
Tunnelling in progress
Soil movementNSF
Resisting force
Lateral
Pilesdeflection
Transverse Settlement Trough due to Tunnel BoringLocation:Settlement Array, CS-9A (SS-9-1A-T )
Underground South Structures : Petchaburi Station to Rama IX Station
10
-5
0
5 9-1- 9-1- 9-1- 9-1- 9-1- 9-1-F 9-1- 9-1- 9-1-I 9-1-J 9-1- 9-1-L 9-1- 9-1- 9-1- 9-1- 9-1- 9-1- 9-1- 9-1-T
-25
-20
-15
-10
t, m
m
Instrumentation or Reading Error
-40
-35
-30
Sett
lem
ent
PeckNB i factor 9 22 m
-55
-50
-45
NB SB
1st 2ndNB i-factor = 9.22 mSB i-factor = 9.62 mVs = 2%
-600 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Distance, m
-8m(NB) 0m(NB) +8m(NB) +38m(NB)79 (NB)/0 (SB) 90 (NB)/ 30 (SB) 122 (NB)/ 67 (SB) 172 (NB)/ 125 (SB)
Figure 5.18: Transverse Settlement Trough due to Tunnel Boring (Parallel Running)
+79m(NB)/0m(SB) +90m(NB)/+30m(SB) +122m(NB)/+67m(SB) +172m(NB)/+125m(SB)+688m(NB)/+430m(SB) +715m(NB/SB) Peck's
Vertical Movement Contour for Twin Tunnels (Case 3)
Loganathan and Poulos (1998)’s method
E=5,000 kNlm^2 E=5,000 kNlm^2
E=4,300 kNlm^2 E=4,300 kNlm^2
E=68,170 kNlm^2 E=400,000 kNlm^2
Plastic PointPlastic Point
Yield Point
RESPONSE OF PILE FOUNDATION TO TUNNELLINGTO TUNNELLING
• Pile lateral deflection and bending moment– Transversely (Perpendicular to tunnel advancing
direction)– Longitudinally (Parallel to tunnel advancing direction)
• Tensile force in pile– Possible near pile head depending on the type of restraint
• Dragload (additional axial force) in pile– Above tunnel springline or invert level
• Pile settlement– Due to downdrag
• The type of response depends on the tunnel-pile relative position
Bangkok Tunnelling Experiences
RISK IN TUNNEL CONSTRUCTIONRISK IN TUNNEL CONSTRUCTION
Causes of Soft Ground Tunnel CollapsesCauses of Soft Ground Tunnel CollapsesCauses of Soft Ground Tunnel CollapsesCauses of Soft Ground Tunnel Collapses
RISK IN TUNNEL CONSTRUCTIONRISK IN TUNNEL CONSTRUCTION
• Considerably High• Inherent Uncertainty in Geological • Inherent Uncertainty in Geological
Condition (Variability in Ground Type & Groundwater)& Groundwater)
• Potential of Large-scale accidentsD t Thi d P t (U b • Damages to Third Party (Urban tunnelling)
Th k YThank You