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Northwest Trunk Presentation
NORTHWEST TRUNK TRENCHLESS SCUGOG RIVER CROSSING – CONTRACT 1 BY: SEAMUS TYNAN P.ENG WARD AND BURKE MICROTUNNELLING LTD 28th August 2014 PRESENTATION OUTLINE 1. Project Overview • • • Location Geology Construction Approach 2. Microtunnelling - Methodology • • • • • • • Overview of System AVN Microtunnelling Machine Slurry Separation Plant Concrete Microtunnelling Pipe Interjacking Stations (IJS) Lubrication TBM Guidance Systems 3. Shaft Construction Methodology 4. Installation of Concrete Pressure Pipe and Grouting 5. Case Studies 6. Key Project Risks & Mitigation Measures 7. Questions PROJECT GEOLOGY SOIL DESCRIPTION - Till: Silt to Silty Clay,Clasts, - - Cobbles & Boulders - Bedrock: Ottawa / Shadow Lake Formation CONSTRUCTION SCOPE Reception Shaft 6m Ø Caisson 14m Deep Launch Shaft 9m Ø Caisson 13.2m Deep 2.0 MICROTUNNELLING - OVERVIEW 3D Schematic What Characterizes Microtunnelling • Trenchless construction • Pipe Jacking • Remotely controlled execution • Minimized excavated material • No requirement for dewatering • Often the most efficient method of pipe installation 6 Applications & Benefits • No Requirement for Dewatering – Environmentally Friendly and less surface disruption • Smaller shaft sizes – Smaller working footprint • Ability to stabilize the cutting face with slurry pressure. Very low risk of surface settlement as a result. Ideal for major highways and rail crossings • Remote Operation – No Requirement for physical work in the tunnel providing superior Health and Safety benefits • Extremely accurate alignments with tolerances of +/- 25mm achievable • Curved Alignments Possible in both horizontal and vertical plane • Ability to break down cobbles and boulders due to advancements in cutting head design and TBM torque increases • Applicable to a large range of sizes, 600mm to 3000mm ID (typical) 7 Applications & Benefits Continued • Can be used as a conduit for water mains, gas & oil lines, jet fuel lines and as a product tunnel for sewer and drainage lines . Direct Installation of product pipe for Sanitary Sewers • Minimizes surface disruption – two working locations • Inherent strength of lining – concrete is the strongest lining available • Minimal reinstatement required 8 Typical Tunnel Drive Lengths • Dependent on the TBM size & geology but a general guide:• AVN600 – max drive length – 170m – 30 inch outside diameter • AVN900 – max drive length – 300m – 43 inch outside diameter • AVN1200 – max drive length – 800m – 56 inch outside diameter • AVN1500 – max drive length – 800m – 69 inch outside diameter • AVN1800 – max drive length – 1200m – 81 inch outside diameter • AVN2000 – max drive length – 2000m – 91 inch outside diameter • AVN2400 – max drive length – 3000m – 107 inch outside diameter 9 AVN1500 HERRENKNECHT MTBM 10 Technical Considerations • No dewatering of the existing ground water is required • Drives of several hundred meters are readily achievable • Accuracies of ~40mm are easily achieved • Ground support provided immediately after excavation • Can excavate through cohesive & non cohesive soil as well as rock • Method most suitable to poor ground conditions 11 3.0 MICROTUNNELLING – SLURRY SEPARATION PLANT Separation Systems • Primary solids removal >3mm • Secondary solids removal >45μm • Tertiary treatment - centrifuge Slurry • Main purposes are to act as transport medium for cuttings, & provide face stability • Main slurry parameters that need to be checked regularly are:• Slurry density – mud balance • Viscosity – marsh funnel • Sand content – sand content kit • SG of slurry < 1.3 – otherwise saturation is reached • Separation System must be able to cope with accumulation of ultrafine solids • Conventional screening & cyclone methods fail to remove clay fraction leading to a successive densification of the slurry 13 Jacking Pipes 14 Jacking Pipes – Joint Detail Example for 1500mm ID Pipe • 1.800m OD concrete pipe (56 inch OD), 60MPa concrete • Can withstand axial load of 11,000kN (1100 Tonnes) (different for each size pipe) • Ultimate line load of 180kN/m (unconfined, different for each size pipe) • Waterproof joint – dry internal tunnel 15 MICROTUNNELLING – 1800mm OD CONCRETE MICROTUNNELLING PIPE VIEW INSIDE CONVENTIONAL ROCK BORE TUNNEL MICROTUNNELLING – VIEW INSIDE 1800mm OD MICROTUNNEL Intermediate Interjack Stations • Used to limit the stresses applied to pipes and thrust wall • Used when jacking frame cannot provide enough thrust for tunnel length • A number of interjacks can be used per tunnel to achieve the desired length 19 Intermediate Interjack Stations 20 Jacking Pipes – Lubrication Pipes • Typically every 6th pipe 21 MICROTUNNELLING - LUBRICATION Jacking Pipes – Effect of Lubrication • Case Studies • Keswick – 340m compound curved tunnel • 1.43m concrete pipe, silty sandy material • Tunnel surface area = 1530m2, push through force = 640kN • Tunnel interface friction = 0.42kN/m2 = 0.42kPa (NO INTERJACK REQUIRED) • Elgin Mills – tunnel length 740m • 1.800mm OD concrete pipe, sandy silty clayey material • Tunnel surface area 4138m2, push through force = 1275kN • Tunnel interface friction = 0.31kN/m2 = 0.31kPa (NO INTERJACK REQUIRED) Bentonite Lubrication • Viscosity measured using marsh funnel • Measures time to pass 946ml through venturi • Crude measure but good site test • Base measurement is water at 26 seconds 23 Tunnel Alignment • Straight alignment – laser guidance good up to ~ 250m (820 ft) • Operate on line of sight – laser placed in starting shaft • Can keep line and grade within ~ 25mm • Ideal for gravity storm and sewer lines – any straight tunnel 24 Tunnel Alignment 25 Curved Tunnel Alignments • Robotic Total Station Guidance System Running Inside Tunnel • Horizontally curved tunnel to eliminate additional shaft in difficult ground 26 3.CONSTRUCTION OF SHAFTS TUNNELLING SHAFT CONSTRUCTION – CAISSON SINKING 2 Shafts Required On Scugog Project ― ― ― ― ― ― ― Minimal Surface Set-Up Time Monolithic Construction NO – DEWATERING Required QA/QC Approved Materials - Concrete Efficient Design – Ward and Burke Microtunnelling Ltd Meets Canadian Foundation Engineering Manual and CSA Standards Incorporates O.Reg Safety Requirements, Ladder Access Etc. CONSTRUCTION OF SHAFTS CONSTRUCTION OF SHAFTS CONSTRUCTION SEQUENCE FOR CONCRETE LINED SHAFT CONSTRUCTION SEQUENCE FOR CONCRETE CAISSON SHAFT CONSTRUCTION SEQUENCE FOR CONCRETE CAISSON SHAFT Installation of Safety Systems 5.0 INSTALLATION OF CONCRETE PRESSURE PIPE AND GROUTING Use of Microtunnelling Pipe as Secondary Liner • Concrete jacking pipe used as product pipe for storm & sewer applications • Completed waterproof tunnel • Also used as secondary liner for utilities – casing and carrier • To date:- water, electrical, jet fuel lines, gas lines, telecommunications etc. • Multiple services can be installed in the same tunnel to maximize use of space • Annular area between utilities & concrete pipe can be grouted or remain open • Utilities installed from one side and then pushed into tunnel on “spiders” 4.0 INSTALLATION OF CONCRETE PRESSURE PIPE AND GROUTING Custom Pipe “Spiders” 4.0 INSTALLATION OF CONCRETE PRESSURE PIPE AND GROUTING Lowering CPP into specially designed hydraulic jacking frame CPP watermain being installed complete with grouting hose. 4.0 INSTALLATION OF CONCRETE PRESSURE PIPE AND GROUTING Jacking frame with 200T/450T Capacity 4.0 INSTALLATION OF CONCRETE PRESSURE PIPE AND GROUTING ANNULUS GROUTING 5.0 CASE STUDIES River Dargle Crossing - Bray Project Brief • • • Provide a system to transport sewage from Bray pump station to the newly constructed treatment works 600 and 800mm id pumped rising mains were needed to fulfil all hydraulic requirements Pipeline route crossing the River Dargle. Bray Pump Station River Dargle Direction to new treatment works • Construction Constraints Geotechnical • • Proximity of Structures and services • • • • • Soft medium plasticy clay with low undrained shear strengths (Su < 30 kPa for over 15m deep) Main East coast railway 10m from works area with 98 trains passing daily Two deep retaining walls each side of the River Dargle Existing pump station and sea outfall. Gas main and fibre optic eircom cable in works area. Working pressures of rising main • System needed to withstand pressures > 7.5 bar Bray Pump Station 6m High Retaining wall 4m High Retaining wall Main East Coast Rail Line Bridge Gas and Fibre Optic Lines Design Solution • In situ caisson and microtunnel construction • • In situ caissons sunk in the wet would prevent the possibility of basal heave, lateral ground deformation, and surface settlements. The in situ caissons could provide the tensile anchor block resistance for the rising main pipework where a segmental shaft system would have failed. The microtunnel construction would prevent damage to the existing retaining walls, rail line, sea outfall, and existing pump station. Construction of 7m id x 10 m deep launch caisson • Site Clearance, cutting shoe positioning, and steel fixing Construction of 7m id x 10 m deep launch caisson • Fixing of guide/jacking collar Construction of 7m id x 10 m deep launch caisson • Sinking in the wet to prevent basal heave, lateral ground deformation, and surface settlement – – – Sinking of fifth lift, 8-10m deep. A Kobelco 235 with clam shell used for excavation 4 no. 100T hollow jacks used to sink caisson with excavation process simultaenously Construction of 7m id x 10 m deep launch caisson • Plugging in the wet – Concrete delivered to the formation via tremie pipe. Construction of 5m id x 12.1 m deep reception caisson • Site clearance, cutting shoe positioning, and shuttering Construction of 5m id x 12.1 m deep reception caisson • Construction of guide/jacking collar Construction of 5m id x 12.1 m deep reception caisson • Sinking caisson in the wet – – A CAT 328 with clam shell was used to excavate inside caisson 4 no. 100T hollow jacks were used to sink caisson as excavation progressed 1200 id Tunnel Construction with Tunnel Boring Machine • Launch eye construction 1200 id Tunnel Construction with Tunnel Boring Machine • Jacking frame installation 1200 id Tunnel Construction with Tunnel Boring Machine • Jacking Pipe installation 1200 id Tunnel Construction with Tunnel Boring Machine • Separation of clay using separation equipment 1200 id Tunnel Construction with Tunnel Boring Machine • Reception of Tunnel Boring Machine 1200 id Tunnel Construction with Tunnel Boring Machine • Launch of Tunnel Boring Machine for 2nd Tunnel Installation of Ductile Iron Rising Main Pipework 5.0 KEY PROJECT RISKS AND MITIGATION MEASURES • • • • • • No Requirement for Dewatering – Environmentally Friendly and less surface disruption Vibration – No Vibration Inducing Equipment Used During Construction Settlement – Controlled Rate of Advance, Pressurised Face Cobbles/Boulders – Mixed Face Cutterhead Frac Out – Pre Engineered Drive Assessment, Filter Cake, Contingency Plans Alignment – ELS or Gyro TBM Guidance Systems • • • • Lubrication Migration – Precise Control of Injection Rate Shaft Construction Through Flowing Soils – Wet Caisson System Risk Assessments – FLRA, Toolbox Talks Application of Ward and Burke + OSHA on all Sites. QUESTIONS?
