andrew axton, glng/ andreas lehr, thiess: constructing the gladstone narrows crossing tunnel
DESCRIPTION
Andrew Axton, Deputy Construction Manager, GLNG and Scott Connor, Senior Project Engineer, Narrows Marine Tunnel, Thiess delivered this presentation at the 2013 Australian Tunnelling conference. The two day conference is supported by the Australasian Tunnelling Society and brings together tunnelling leaders, engineers and industry experts to share best practice in tunnelling design, construction, safety and maintenance. The 2012 program focussed on updates from Australasia’s current and future projects, plus case studies from leading International projects - sharing best practice and lessons learnt from the forefront of the latest tunnelling projects. For more information about the event, please visit the conference website: http://www.informa.com.au/tunnellingconferenceTRANSCRIPT
Narrows Marine Crossing
REALISING A VISION BY INNOVATING EXCELLENCE
The 12th Australian Tunnelling Conference 21st November, 2013
Andrew Axton (GLNG) Scott Connor (Thiess)
GLNG PIPELINE
OVERVIEW The GLNG Pipeline is a 420 km long 1050 mm diameter gas transmission pipeline running from Fairview to Curtis Island, for the transportation of gas from fields in the Roma, Fairview and Arcadia Valley area across the Callide Range and across the Narrows Channel to Curtis Island.
PROJECT STATISTICS:
• 420 km’s
• 92 land deeds
• 265 Water Courses to cross
• 51 classed as major
• 2 State Development Areas (SDAs) to cross
• Run parallel with the other Proponents Pipelines
• Narrows crossing
• 3 camps
• 6 stockpile locations on the route
• 2 stockpile locations at the Ports
TYPICAL PIPELINE CONSTRUCTION SPREAD
CONSTRUCTION ACTIVITY
Clear and Grade Stringing Bending
Pipe Welding
Excavation / Trenching Lower In Bedding and Padding
Restoration / Rehabilitation
PIPELINE
Legend: Clearing Trenching Welding FJC Lowering Backfilling Rehabilitation
Watercourse crossings major
Trenching Across Mudflats
Offshore Trenching (Dredging)
Major Creek Crossing
ORIGINAL CROSSING
METHODOLOGY - TRENCHING
Concept: HDDs (4 drives) & Marine access
2ND ITERATION CROSSING
METHODOLOGY - HDD
3RD ITERATION CROSSING
METHODOLOGY - DIRECT PIPE
Tunnel / Pipeline
Receptor Pad
Launch Pad
Access Road
Mainland Trenched Pipeline
Minor Creek Crossings
TUNNEL CROSSING
METHODOLOGY
OTHER PROPONENTS
METHODOLOGY 1 OF 3
OTHER PROPONENTS
METHODOLOGY 2 OF 3
OTHER PROPONENTS
METHODOLOGY 3 OF 3
CONTRACT DATES
EPC PIPELINE CONTRACT AWARDED TO SAIPEM JUNE 2011
OPTIONEERING CROSSING METHODOLOGY JUNE 2011- MAY 2012
VARIATION GRANTED TO SAIPEM FOR TUNNEL- MAY 2012
SAIPEM AWARD TUNNELLING CONTRACT TO THIESS- SEPTEMBER 2012
GLNG FORMED ‘OWNER’S ENGINEERING TEAM’ (GHD) TO OVERSEE CONSTRUCTION
THIESS COMMENCED CONSTRUCTION OCTOBER 2012
Handover to Andreas
• Early 2012, contacted to discuss options for a SUBTERRANEAN CROSSING
• HDD vs. DP vs. TBM
• Highest safety and environmental standards
• Minimal footprint
• 42 year operational life
• Fast track delivery
• Integrated project partner
UNDERSTANDING THE VISION
• Start tunnelling within 12 months of feasibility study
• Minimal geotech / bathymetry data available
• Extremely compressed design, procurement and construction schedule
• Developing a “best-for-project” solution
EARLY CHALLENGES
INITIALLY PROPOSED: Alignment • Maintain 2d cover except at
entry/exit locations • Minimise grade • Minimise length The problem? Too little
geotech Site layout • Shaft operation with gantry
crane • Pipes stringed on adjacent site
and fed into tunnel via 1:7 ramp (constructed on critical path)
The problem? Slow and riskier operation
REALISING THE VISION CHALLENGES OF
TURNING AN IDEA INTO ‘READY TO BORE’ IN
12 MONTHS
• Early assessment conducted o Single-beam bathymetry
o Continuous seismic profiling (CSP)
o Underwater seismic refraction (USR)
o Land seismic refraction (LSR)
• Borehole drilling on mainland site
• Later marine investigation
• Final revalidation of all design assumptions after g.I. Complete (GDR)
REALISING THE VISION OVERCOMING THE GEOTECH
CHALLENGE
Composite seismic section beneath channel
CSP Section beneath mudflats
REALISING THE VISION FINAL GEOTECH BASELINE
THE SOLUTION?
Integrated site layout
• Turn shaft into 400m decline
• Pipe stringing adjacent to decline
• Rapid TBM rolling stock support without rushing
• Rapid pipe install
REALISING THE VISION INTEGRATING THE
SOLUTION TO INCREASE EFFICIENCY
Final Integrated Site Layout – Tunnelling and Pipe Install
Original “Tunnelling Dedicated” Site
Concept Integrated solution
Fully integrated launch shaft design • Improved TBM launch • Improved TBM production • Improved pipe installation • Safer • TBM thrust foundations combined with pipe thruster
REALISING THE VISION INTEGRATING THE
SOLUTION Concept
Integrated solution
REALISING THE VISION CLIENT/CONTRACTOR
INTEGRATED SOLUTION
• Conservative approach – adjusted as data arrived
• Experienced designers familiar with the scope
• Collaborative design reviews
• Continual refinement
• Alignment example o Used initial data to drop
concept alignment
o Used final borehole to raise exit point
REALISING THE VISION OVERCOMING THE DESIGN
‘NO TIME, NO DATA’ CHALLENGE
8m
3m
Example: Alignment
Low-point BEFORE
Low-point AFTER
350m
• Procured and reconditioned 4.05m EPB TBM (herrenknecht) and matching moulds
• Selective approach to early procurement of critical items – eg, new TBM cutterhead, additional TBM capability (grouting, slurry mode), rolling stock, mould refurb.
• Offsite TBM commissioning, for quick build and launch on site
REALISING THE VISION OVERCOMING THE
PROCUREMENT CHALLENGE
As at November 2013 • 3600m complete • Traversed past low point - commenced incline to island • 125m/wk average vs 95m/wk target • Reception shaft complete
REALISING THE VISION PROGRESS TO DATE
REALISING THE VISION
EPB successful - geotech predominantly stiff sandy clay
• 300m traverse of fault – gravels
• Areas of high permeability
• Use of ground treatment chemicals critical: foam, polymer, bentonite
Communication is the key to delivering fast track project
CHALLENGES AND LESSONS LEARNT
TO DATE
Handback from Andreas
POST
BREAKTHROUGH
ACTIVITIES
• INSTALLATION OF FOC
• INITIAL FLOOD OF TUNNEL
• PIPE PUSHING OPERATION
• HYDRO-TESTING OF PIPE
• CONSTRUCTION OF END PLUGS
• SECONDARY FLOOD OF TUNNEL
• BACKFILL AND REINSTATEMENT
Typical Cross section (Operation)
FLOODING OF TUNNEL
• TUNNEL TO BE FILLED WITH SEAWATER
• OFFSHORE PUMPING FROM PONTOON ANCHORED TO SEABED
• EA AMENDMENT FOR EXTRACTION
• 3 DAY OPERATION • 40,000M3 • 250L/SEC PUMP RATE • SCREENING TO 1MM
PIPE PUSHING OPERATION
• FABRICATE PIPE STRINGS APPROXIMATELY 216M IN LENGTH
• THRUST INTO TUNNEL VIA PIPE ROLLERS
• 750 TONNE HERRENKNECHT PIPE THRUSTER
• 5M STROKE 6MIN STROKE TIME
• 1 MIN RETRACTION TIME
• 216M IN 6 HOURS
Roller-way Arrangement
Roller way arrangement - plan view and longitudinal section
Pipe Roller typical sections
Pipe launch head detail
PIPE INSTALLATION
AERIAL STRINGING YARD
Tunnel Centreline Triple Joint
Prefabrication Yard
GTP Right-of-Way
Service Crane Way
Offices Area
Welding Stations at
36m Centres
or Welding train
Pipe Thruster
Mainland Curtis Island
END PLUG DESIGN
STATS • MAINTAIN SEAWATER LEVEL INTO TUNNEL @RL-2.47M • 83.35M MAINLAND TUNNEL PLUG • 20M CURTIS ISLAND PLUG • 10MPA CONCRETE FLOWABLE FILL • 823M3 OF CONCRETE • 5 STAGE BACKFILL TO PREVENT FLOATATION
Mainland
BACKFILL AND REINSTATEMENT
Curtis Island
GLADSTONE’S LEGACY
• ASH FROM GLADSTONE POWER STATION OVER 30 YEARS RECLAIMED SECTION OF TIDAL MUD FLATS
• LAND GIFTED TO GLADSTONE REGIONAL FOR REHABILITATION
• TUNNEL SPOIL TO FORM 500MM CAPPING LAYER TO THE POND
• FUTURE RECREATIONAL OR SPORT FIELD USAGE
Fill Material Lime Guard Layer (min 5kg/m2)
Existing Ash
• THIESS CONTRACT – TIP AND GO
• GLNG FORMED A COST REIMBURSABLE CONTRACT WITH GRC TO ALLOW TIPPING TO COMMENCE
• CONTRACT COVERED TOPSOIL STRIPPING, DRYING, SPREADING AND COMPACTING TUNNEL SPOIL AND REPLACING THE TOPSOIL, READY FOR SEEDING
ASHPOND CAPPING
OCTOBER 2013
QUESTIONS?