PORTO PORTO Project and construction of Underground d stations s and tunnels (TBM and NATM) in heterogeneous masses for Metro do Porto. António Viana da Fonseca (viana@fe.up.pt) António Topa Gomes (atgomes@fe.up.pt) 1
Metro do Porto Project and construction System of Light Metro of the Metropolitan Area of Porto Metro do Porto The Project INDEX Geological Conditions Tunnels: -TBM(sellection and adaptations) and other solutions - Monitoring and Control Tunnels Underground stations: - Cut and Cover: active support or unsupported shafts (arch effects) - Cavern with access shafts (unsupported) and mining by NATM Building Risk Analysis: - Surveying Procedures (limits and alerts; reactions and solutions) 2
Metro do Porto And there has been a POPULAR MYTH An underground metro would never be a reality in Porto!!! The granite is impenetrable?... Metro do Porto The Project 3
Metro do Porto. Routes Reconvertion of more than 50Km of existing lines. Construction of 13 km of surface new lines. Construction of 7 Km of tunneling new lines. Construction of 2 Principal Interface Structures. 74 Stations with decks of 70m length and 0,30m height. 11 Underground Stations. 19 Rehabilitation and modernization of existing Surface Stations. 44 New Surface Stations. Metro do Porto. Routes Frentes de obra Obra activas activas em em Jan/2001 Out/2001 FEV 2002 6 7 6 14 5 Line C Tunneling new lines 8 6 12 9 Legenda: Main Undergro ound Stations 11 15 10 4 1 - Túnel (Tuneladora) 2 - Est. Heroísmo 3 - Est. 24 de Agosto 4 - Trindade (D. Redes p/ Trincheira) 5 - Matosinhos - P.I. Via Rápida 6 - Matosinhos - Desvios Redes p/ Via 7 - PMO Guifões 8 - Ramal acesso PMO Guifões 9 - Maia (Desvios Redes e Plataforma) 13 3 2 1 Line S 4
Metro do Porto Geological Conditions Metro do Porto. Geological Conditions Distribution of Porto Granite Iberian Granites 5
Metro do Porto. Geological Conditions Geological complexity of the region Douro PTSZ River CIZ OMZ 1 2 3 4 5 6 CIZ Central Iberian Zone; OMZ Ossa-Morena Zone; PTSZ Porto-Tomar Shear Zone; (1) Cenozoic cover deposits; (2) Cambrian CIZ (Schist and Graywacke Complex); (3) Precambrian metassediments OMZ; (4) Madalena granite (late orogenic); (5) Ermesinde granite (hybrid sin-tectonic); (6) Porto granite (peraluminous sin-tectonic) Metro do Porto. Geological Conditions Prevailling conditions of Porto Granite - All Weathering Grades irregular geometry between weathered and sound rock mass 6
Metro do Porto. Geological Conditions Erratic profiles of highly weathered to sound granitic masses Metro do Porto. Geotechnical Characterisation SOIL RO OCK Geomechanical classification & characterization Fract. RQD N SPT Geomechanical Group Weathering (W) Fracturation (F) GSI NSPT G1 W1 F1-F2 65-85 - G2 W2 F2-F3 45-65 - G3 W3 F3-F4 30-45 - G4 W4 F4-F5 15-30 - G5 W5 n.a. - > 50 G6 W5/W6 n.a. n.a. < 50 G7 n.a. n.a. n.a. var. Ru (Mpa) (kn/m3) mb s Ed (GPa) G1 90-150 25-27 7.45 6.9E-2 35 G2 30-90 25-27 3.2 7.5E-3 10.7 G3 10-35 23-25 0.98 7.5E-4 1.0 G4 1-15 22-24 0.67 0 0.4 N SPT (kn/m3) c (Mpa) ( ) Ed (GPa) G5 > 50 19-21 0.01-0.05 32-36 0.05-0.20 G6 < 50 18-20 0-0.02 30-34 0.02-0.07 G7 variable 18-20 0 27-29 <0.05 7
Metro do Porto. Geotechnical Characterisation Number of boreholes (1st phase): classical (drilled) and DPR (continuous parameter recording) Drilled Boreholes Work Conventional rotary Parameters recording (DPR) Nº Comp.(m) Nº Comp.(m) LINE C 122 3522 18 592 LINE S 75 2068 11 288 LINE J 10 560 - - Stations Line 'C' 74 1164 - - Stations Line 'S' 117 3004 - - TOTAL 398 10318 29 880 26,4 m 10,5 m 17,0 m Metro do Porto. Geological Conditions vs operation mode Quality of Porto Granite and possible alternative EPB operation modes 1. Granitic mass sound or slightly weathered, no weathered material in the discontinuities. Operation mode-tbm OPEN mode 2. Granitic mass with very weathered material in fractures; these fractures may communicate with overlaying parts of completely weathered granite. 3. Very weathered or completely weathered granite (almost granular soil with little or no cohesion). 4. Very weathered or completely weathered granite with blocks of the rock core. CLOSED mode 5. Mixed conditions with both sound mass and completely weathered granite appearing in the face. In all cases the water table is above the tunnel crown 8
Metro do Porto. Campanhã Station - Assessment of Geology Line S (underground) g7 g6 g5 g4 g3 g2 Metro do Porto. Campanhã Station - Assessment of Geology Line C (underground) g7 g6 g5 g4 g3 g2 9
Metro do Porto. Geological Conditions The Geological Model Features in weathered masses of granitic and other igneous rocks. R. Fell et al. 1992 Weathering profile Begonha and Braga, 2002 Metro do Porto. Geological Conditions Geology of Porto Granite All Weathering Grades 10
Metro do Porto. Geological Conditions Weathered Granite (left) underlaying Sound Granite (right) in Places Metro do Porto. Geological Conditions fresh granite weathered granite 11
Metro do Porto. Geological Conditions Diverse weathering Multiple solutions Metro do Porto. Geological Conditions Multiple solutions 12
Metro do Porto. Geological Conditions Mixed solutions Metro do Porto. Geological Conditions Same station, North Side versus South Side Unsupported shafts: the importance of water level lowering 13
Metro do Porto. Geological Conditions North Side: Preparing the breakthrough of TBM Jet-Grouting Type II South Side Preparing the intrusion of the TBM - nails of fibreglass Tunnels TUNNELING BORING MACHINE Earth Pressure Balance 14
Metro do Porto. Geological Conditions for TUNNELING Tunneling - assesment of geology Predicted geology for the Heroismo mined station, assessment by Transmetro Tunnels. Geological and Geotechnical Conditions Geological mapping at the face 15
B A C D D A C B A C D D A C Metro do Porto. Tunnel geometry Geometry F+T MV LV INTERNAL GABARIT MINIMUM CURVES RADIOS MAXIMUM SCALES - TBM 1: 7,80 m - Horizontal: 200 m - Scale: 140 mm - TBM 2: 8,00 m - Vertical: 500 m Gabarit: Gabarit taking the vehicule dynamics, Catenarie, Free passage (0.70m), tubes for cables, Via (STEDEF type), Signals, Ilumination Tunnels. TBM - project Project conditions Tunneling internal diameter: 7.8 8.0m Lined with a tapered universal ring: 1.4m long and 300mm thick Consisting of : 6+1 pre-cast, reinforced concrete segments The tappered rings allow: a minimum radius of 200m 16
Tunnels. TBM (EPB) - Ring Support Supportin rings a PUZZLE!!! Tunnels. TBM (EPB) - Ring Support 17
Tunnels. TBM Earth Pressure Balance (EPB) Project conditions Overburden thickness ranges: 10m 30m With a minimum value of: 3m 4m underneath sensitive buildings (more than 2000 buildings in the influence zone) A complex geologic ambient: Weathered Granite Metro do Porto. Geological Conditions Porto Weathered Granite Weathered Granito do Porto exhibits a METASTABLE structure, which can accentuate a potential for collapse, depending on the high porosity and reduced cohesive strength of the loosed/leached residual soil. 18
Metro do Porto. TBM - Geological Conditions Porto Weathered Granite Weathered Granito do Porto exhibits a METASTABLE structure, which can accentuate a potential for collapse, depending on the high porosity and reduced cohesive strength of the loosed/leached residual soil. The water table is located 10-25m above the tunnel, rarely following the shape of the surface topography. Metro do Porto. TBM - Geological Conditions Porto Weathered Granite Weathered Granito do Porto exhibits a METASTABLE structure, which can accentuate a potential for collapse, depending on the high porosity and reduced cohesive strength of the loosed/leached residual soil. The water table is located 10-25m above the tunnel, rarely following the shape of the surface topography. ADITIONALLY: a large number of old wells and minas (old and small handmade water tunnels), with no register...). The vast number of these elements have modified the hydro-geological characteristics of the ground; so, the water MOVES NOT ONLY IN THE POROUS MEDIUM AND FRACTURES, but ALSO ALONG THESE CHANNELS (MINAS...). 19
Tunnels. TBM TUNNELING BORING MACHINE Selection Criteria Tunnels. Geology vs Tunneling Boring Machine Geology - Criteria for Selection of TBM (Babendererd et al 2004) Unilat. compr. MPa Rock Strength Rock Structure Water Ingress cohesion Cu KN/m² Face Support Shield Lining Install. Jointing RQD Distanc e Grain size < 0.02 mm < 0.06 mm Face Support Shield Lining Install. Volume per 30m³ Consequences on 100 > 250 - - - - - > 2 m - - unlimited pump capacity 90 % 250 90 20 2.0 behind - - - - - - behind TBM unlimited pump capacity TBM 100 75 % 0.6 m 100-50 - behind TBM 75 0.6 - - 50 % 0.2 m - possible behind TBM > 20 l/s pump capacity Rock 50-25 - recom. behind TBM 50 0.2 - - 25 % 0.06 m possibly mech. recom. in TBM area > 10 l/s face support 25-5 - recom. < 25 % < 0.06 m mech. required under shield > 5 l/s face support 5-1 recom. required under shield < 25 % < 0.06 m mech., possibly required under shield > 2 l/s methodology EPB/Slurry < 1 > 30 - required under shield < 25 % < 0.06 m vary mech., possibly required under shield > 2 l/s methodology EPB/Slurry Soil 30 mech., under - recom. required > 30 % possibly required under shield > 2 l/s methodology shield 10 EPB/Slurry 10 under shield under shield EPB / - recom. required immed. > 20 % < 50 % required immed. > 2 l/s methodology 5 grout. Slurry grout. under shield 5 under shield immed. EPB / - required required grout. > 10 % < 30 % required immed. > 2 l/s methodology Slurry 1 grout. under shield under shield immed. EPB / 0 required required grout. > 10 % < 20 % required immed. > 2 l/s methodology Slurry grout. 20
Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to the extreme variability, EPB s OPERATED IN CLOSED MODE. Tunnels. Geology vs Tunneling Boring Machine Geology Weathered Granite Different Cohesion Different Permeability!... 21
Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: 22
Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: - face support pressure; - apparent density of the muck in the chamber; - weight to be extracted a each ring; - longitudinal grouting pressure and volume; and, - aditional bentonite slurry injection volume and pressure. Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: - face support pressure; - apparent density of the muck in the chamber; - weight to be extracted a each ring; - longitudinal grouting pressure and volume; and, - aditional bentonite slurry injection volume and pressure. 23
Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: - face support pressure; - apparent density of the muck in the chamber; - weight to be extracted a each ring; - longitudinal grouting pressure and volume; and, - aditional bentonite slurry injection volume and pressure. Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: - face support pressure; - apparent density of the muck in the chamber; - weight to be extracted a each ring; - longitudinal grouting pressure and volume; and, - aditional bentonite slurry injection volume and pressure. 24
Metro do Porto. TBM - Design Tunneling Design Approach TBM Advance Plan Due to extreme variability, the EPB s OPERATED IN CLOSED MODE. A special care to avoid any excessive displacements or subsidence due to volume loss ahead, above and behind implied a PAT ( Plan of Advance of TBM ), which included, in adition to design information, a report on the evaluation of the TBM working parameters, containing the definition of the reference value and the relevant operational range for: - face support pressure; - apparent density of the muck in the chamber; - weight to be extracted a each ring; - longitudinal grouting pressure and volume; and, - aditional bentonite slurry injection volume and pressure. Tunnels. TBM Earth Pressure Balance (EPB) EPB Characteristics Injection of Conditioning Additives into Tool Gap Cutter Head Diam.: 8.74 8.94m Max. Tunneling Thrust Force: 70,613 kn Max. Cutterhead Thrust Force: 22,200 kn Max. Cutterhead Torque: 12,900 kn Breakaway Torque: 15,000 kn Total Installed Power: Approx. 4 MW 25
Tunnels. Criteria for selection of TBM Selection of TBM Type of Face Support: (1) Pressurized Slurry Tunnels. Criteria for selection of TBM Selection of TBM Type of Face Support: (2) Pressurized Earth Paste (EPB) Fill Weathered Granite Working Chamber Additives Screw Conveyer Cutter Head Pressure Cells 26
Tunnels. Criteria for selection of TBM Range of Slurry- and EPB- TBM Application Considering Grain-size Distribution Ton Schluff Sand Kies Steine Blöcke fein mittel grob fein mittel grob fein mittel grob [ % ] 100 8 4 2 3 6 5 1 90 80 70 60 50 40 30 Slurry-TBM drives 1. Lyon 2. Hamburg 3. Grauholztunnel 4. Wesertunnel 5. Zürich, Hermetschloo-Werdhölzli 6. Zürich, Thalwil 7. Portland, Gravel Alluvium 8. Wittenberg (polymer suspension) 7 20 10 0 0,006 0,02 0,2 0,63 6,3 20 100 0,002 0,06 2 63 200 1000 100 90 80 11 9 10 70 60 50 40 30 EPB-TBM drives 9. Essen, U-Bahn Los 32/33 10. Milano, Passante Ferroviario 11. Metro Porto 20 10 0 0,006 0,02 0,2 0,63 6,3 20 100 0,002 0,06 2 63 200 Grain-size [mm] 1000 Tunnels. Criteria for selection of TBM Slurry limitation High content of fines < 0,06 mm requires expensive separation process EPB limitation High permeability k > 10 - ³ requires intensive conditioning 27
Tunnels. TBM Earth Pressure Balance (EPB) Monitoring of the EPB machine Tunnels. TBM Earth Pressure Balance (EPB) Control of Excavated Material (weight) Reaction procedure : 28
Tunnels. TBM (EPB) - Emergency In an emergency situation Unpredictable situation occurs The responsible engineer is called The instructions are implemented O.K.? The excavation proceeds Meanwhile: The foreman is called Emergency Procedure The supervisor and manager are advised Emergency Procedure Tunnels. TBM (EPB) - Emergency 29
Tunnels. TBM (EPB) Failure! Two Major Accidents!... Tunnels. TBM (EPB) Failure! The second, in 12 Jan. 2001, was dramatic!... A sink hole was induced after 30m of the passing of the face. A house was swallowed and an old lady was killed!... 30
Tunnels. TBM (EPB) Solution From the problem to the solution! Panel Specialists A. Cardoso (FEUP) S. Babendererde E. Hoek P. Marinos (NTUA) Tunnels. TBM (EPB) - Classical Geological Risks The special case of Porto Requirements for Closed Mode Weathered Granite in all stages with variable cohesion and variable permeability Classical EPB- TBM Process Risks - No sensitive control instrumentation - Overcharge of TBM operator for decisions to adapt operation procedure to changed ground conditions 31
Tunnels. TBM (EPB) - Classical Classical EPB - TBM Operation mode Criteria? Muck extraction Open mode? via belt conveyor open mode semi open mode closed mode Muck extraction via screw conveyor not clearly defined Closed mode? Tunnels. TBM (EPB) - Classical Classical EPB - TBM Control instrumentation not sensitive enough to react on frequent changes of geotechnical properties in heterogeneous geology. Operation Panel Process steering by operator without reliable automatism 32
Tunnels. TBM (EPBm) - Face Support Earth Press sures Sensors: (7+2) and (9+2) Tunnels. TBM (EPBm) - Face Support Transfer of Support Pressure 33
Tunnels. TBM (EPBm) - Modified SPECIAL FEATURES OF EPBM The following modifications were made to the configuration: Tunnels. TBM (EPBm) - Modified SPECIAL FEATURES OF EPBM The following modifications were made to the configuration: SET UP OF AN ACTIVE SECONDARY FACE SUPPORT (SFSS): an automatic SYSTEM that pumps bentonite slurry into the excavation chamber, whenever the pressure drops below a preset value; 34
Tunnels. TBM (EPBm) - Modified SPECIAL FEATURES OF EPBM The following modifications were made to the configuration: SET UP OF AN ACTIVE SECONDARY FACE SUPPORT (SFSS): an automatic SYSTEM that pumps bentonite slurry into the excavation chamber, whenever the pressure drops below a preset value; INSTALATION OF AN EMERGENCY DOUBLE PISTON PUMP (EDPP) AFTER THE SCREW CONVEY, in order to deal with the liquid muck and uncontrollable support pressure oscillations; Tunnels. TBM (EPBm) - Modified SPECIAL FEATURES OF EPBM The following modifications were made to the configuration: SET UP OF AN ACTIVE SECONDARY FACE SUPPORT (SFSS): an automatic SYSTEM that pumps bentonite slurry into the excavation chamber, whenever the pressure drops below a preset value; INSTALATION OF AN EMERGENCY DOUBLE PISTON PUMP (EDPP) AFTER THE SCREW CONVEY, in order to deal with the liquid muck and uncontrollable support pressure oscillations; INSTALATION OF A SECOND BELT SCALE, in order to cross-check results of the first scale; and 35
Tunnels. TBM (EPBm) - Modified SIGNIFICANT ADJUSTMENTS TO THE DRIVING SOFTWARE THREE AUTOMATIC ALARM SYSTEMS: Tunnels. TBM (EPBm) - Modified SIGNIFICANT ADJUSTMENTS TO THE DRIVING SOFWARE THREE AUTOMATIC ALARM SYSTEMS: 1. EXCEEDING THE EXTRACTED WEIGHT upper limit, automatically stops the advance; 36
Tunnels. TBM (EPBm) - Modified SIGNIFICANT ADJUSTMENTS TO THE DRIVING SOFWARE THREE AUTOMATIC ALARM SYSTEMS: 1. EXCEEDING THE EXTRACTED WEIGHT upper limit, automatically stops the advance; 2. EXCEEDING THE FACE SUPPORT PRESSURE lower limit, automatically switches on the SFSS; Tunnels. TBM (EPBm) - Modified SIGNIFICANT ADJUSTMENTS TO THE DRIVING SOFWARE THREE AUTOMATIC ALARM SYSTEMS: 1. EXCEEDING THE EXTRACTED WEIGHT upper limit, automatically stops the advance; 2. EXCEEDING THE FACE SUPPORT PRESSURE lower limit, automatically switches on the SFSS; 3. EXCEEDING THE APPARENT DENSITY OF THE MUCK lower limit; AND 37
Tunnels. TBM (EPBm) - Modified SIGNIFICANT ADJUSTMENTS TO THE DRIVING SOFWARE THREE AUTOMATIC ALARM SYSTEMS: 1. EXCEEDING THE EXTRACTED WEIGHT upper limit, automatically stops the advance; 2. EXCEEDING THE FACE SUPPORT PRESSURE lower limit, automatically switches on the SFSS; 3. EXCEEDING THE APPARENT DENSITY OF THE MUCK lower limit; AND the KEY POINT is the utilization of CONTINUOUS ANALYSIS OF THE TBM PERFORMANCE (REAL TIME and BACK-ANALYSIS) Tunnels. TBM (EPBm) - Face Support The solution for Metro do Porto TBM Additive Face Support System Sensitive crown area prone to unintended pressure drop Additional slurry injection system Drops of predetermined support pressure will be automatically compensated by slurry injection. 38
Tunnels. TBM (EPBm) - Face Support The solution for Metro do Porto TBM - EPBM Secondary Face Support System (SFSS) Suspension Container Pressure Control Tunnels. TBM Earth Pressure Balance (EPBm) Modified operation of the EPBM machine with an Active Secondary Face Support System d (9+2) es Sensors: (7+2) and Earth Pressure Scheme from Babendererde, Cardoso, Hoek, Marinos, report to Metro do Porto, 2001 39
Tunnels. TBM Earth Pressure Balance (EPBm) Porto EPBM Tunnels. TBM Earth Pressure Balance (EPBm) 40
Tunnels. TBM Earth Pressure Balance (EPBm) Combined Tool Arrangement Disks and Shave Bits Tunnels. TBM (EPBm) - Face Support Control of the extracted muck weight The TBM incorporates a conveyor belt system for the removal; The Weight was measured by using TWO BELT SCALES Proved an accuracy of 3-4%; 41
Tunnels. TBM (EPBm) - Face Support Control of the extracted muck weight The TBM incorporates a conveyor belt system for the removal; The Weight was measured by using TWO BELT SCALES Proved an accuracy of 3-4%; HOWEVER, to adjust the reference value and the operation It was NECESSARY TO EXECUTE FREQUENT FACE MAPPING (under pressure by visualization) and to estimate the GROUND IN SITU DENSITY, at least every 15m (horizontal survey); Tunnels. TBM (EPBm) - Face Support Control of the extracted muck weight The TBM incorporates a conveyor belt system for the removal; The Weight was measured by using TWO BELT SCALES Proved an accuracy of 3-4%; HOWEVER, to adjust the reference value and the operation It was NECESSARY TO EXECUTE FREQUENT FACE MAPPING (under pressure by visualization) and to estimate the GROUND IN SITU DENSITY, at least every 15m (horizontal survey); Also, necessary to SUBSTRACT the weight of the CONDITIONING AGENTS ADDED during excavation (average 20-30m 3 of water with polymer)! 42
Tunnels. TBM (EPBm) - Face Support Control of the extracted muck weight The TBM incorporates a conveyor belt system for the removal; The Weight was measured by using TWO BELT SCALES Proved an accuracy of 3-4%; HOWEVER, to adjust the reference value and the operation It was NECESSARY TO EXECUTE FREQUENT FACE MAPPING (under pressure by visualization) and to estimate the GROUND IN SITU DENSITY, at least every 15m (horizontal survey); Also, necessary to SUBSTRACT the weight of the CONDITIONING AGENTS ADDED during excavation (average 20-30m 3 of water with polymer)! ADITIONAL CONDITION: tunnel with very tight curves (R=200m) => the balances were not correctly loaded (<accuracy) Tunnels. TBM (EPBm) - Face Support Installation for Conditioning injection Injection of Additives Foam generator 43
Tunnels. TBM (EPBm) - Face Support Management of face support pressure As important as the weight control, this PARAMOUNT factor was: Assured by IMPOSING A MINIMUM EFFECTIVE PRESSURE; ie, the support pressure SHOULD BE TRANSMITTED from the bulkhead to the face VIA SOLID PARTICLE and NOT ONLY through the pore pressure or compressed air. Natural Ground: Clay as Support Medium Tunnels. TBM (EPBm) - Face Support Management of face support pressure As important as the weight control, this PARAMOUNT factor was: Assured by IMPOSING A MINIMUM EFFECTIVE PRESSURE; ie, the support pressure SHOULD BE TRANSMITTED from the bulkhead to the face VIA SOLID PARTICLE and NOT ONLY through the pore pressure or compressed air. CONSEQUENCE: CHAMBER MUST ALWAYS BE FULL OF SOLID MIXTURE with adequate density (around 14kN/m 3 ) As additional safety measure, THE REFERENCE SUPPORT PRESSURE WAS DEFINED AND MEASURED AT THE TOP OF THE BULKHEAD (1m below the tunnel crown), so that the other pressures were higher 44
Tunnels. TBM (EPBm) - Face Support Face with Gravel and Stones - Conditioning is required Tunnels. TBM (EPBm) - Face Support Management of face support pressure (cont.) The density of the muck was evaluated systematically by measuring pressures at different bulkhead heights (dividing the difference in pressure by the height between monitoring points). Elements of Face Pressure Even with all this management care instantaneous density figures fluctuated significantly (apparent!!!) 45
Tunnels. TBM (EPBm) - Face Support Control of Support Pressure and extracted muck weight Earth Pressure es Sensors: (7+2) and (9+2) Cutter Head Rotation Pressurized Earth Paste Additives Advance Force Pressure Cells Screw Conveyor Rotation Tunnels. TBM (EPBm) - Face Support Conditioning agents Both polymer and foam have proved to work successfully! POLYMERS couldn t help to reduce the very high tool-wear rate FOAM greatly reduced the wear rate, BUT required more complex and smoother operation of the screw conveyor. Excessive wear 46
Tunnels. TBM (EPBm) - Face Support Effects on Filtration of Different Conditioning Agents Limited filtration of water Pressurized earth paste Filter cake Conditioned with: Bentonite Slurry 96% water 4% solids Deep filtration of slurry Pores blocked by polymer bundle Polymer Slurry 99,8% water 0,2% pseudo solids High filtration of air and water Forces transferred grain to grain Foam 91% air 8,8% water 0,2% foaming agent (300-600 l air/m 3 soil) Tunnels. TBM (EPBm) - Face Support Earth Paste Conditioned with Foam Earth Paste when air Proper Conditioning diffused after TBM stop 47
Tunnels. TBM (EPBm) - Modified Face conditions and TBM parameters Analysis of the TBM operational parameters allows the detection ti of ground conditions (similarly il l to oil drilling or geotechnical investigations campaigns DPR...). Combination of CUTTER HEAD THRUST, ADVANCE SPEED and DISC WEAR Thanks to frequent face surveys, it was possible to CALIBRATE THE INTERPRETATION PARAMETRICAL ANSWER, to avoid systemathic survey of the face! Tunneling (TBM - EPBm) 2 Units working simultaneously 48
Tunnels. TBM (EPBm) - Modified It made possible to achieve very good results in TBM ADVANCE RATES AND PRODUCTION TBM operated 24-24h in six-day week, one of which was used to execute cutterhead maintenance under hyperbaric conditions, leading to: 1. Average daily production: 5 rings = 7m; 2. Best day (06/02/2002): 13 rings = 18.2m; 3. Best week (7-13 October 2002): 56 rings = 78.4m; 4. Best month (August 2003): 180 rings = 252m. VERY POSITIVE AND ABOVE THE USUAL STANDARD! Tunnels. TBM (EPBm) Starting trenches 49
Tunneling (TBM - EPBm) 2 TBM Working in Working out Tunnels NATM TUNNELS NATM 50
0.00 0.00 0.00 Tunnels NATM Tunnel J 300 m long Cross-section 30 m 2 Average Cover 18 m Relatively competent materials Tunnels NATM Tunnel J 51
Tunnels NATM Tunnel J Final Lining - Shotcrete Tunnels NATM Lapa Tunnel Rehabilitation of na existent tunnel - creation of a 50 cm thickness invert in the zone passing over tunnel J; - contact injection along the entire tunnel in order to guarantee the contact between the support and the ground; - lining recover by water under pressure and adding a thin shotcrete membrane reinforced with a wire mesh or total substitution of the existent lining; - Watertighness and drainage of the tunnel, collecting water in the leaking points. 52
Tunnels NATM Lapa Tunnel Tunnels NATM Lapa Tunnel 53
Cut & Cover Excavations CUT & COVER EXCAVATIONS Underground stations 54
Cut & Cover Stations 24 Agosto Station Diaphagm walls Universal solution for the tender phase Enormous difficulties for the construction Cut & Cover Stations 24 Agosto Station Diaphagm Wall Underpinned Diaphagm Wall Berlin type Wall 55
Cut & Cover Stations 24 Agosto Station Longitudinal Section Cut & Cover Stations 24 Agosto Station Cross Section 56
Cut & Cover Stations 24 Agosto Station Cross Section Cut & Cover Stations Solutions With Piles The smaller dimension allowed to pass over different materials New equipments have a great torque and can easily perforate W4 materials Initial concern with the water table position: Initial solutions were watertigh (in the walls) Drainage during construction 57
Cut & Cover Stations Trindade Station Cut & Cover Stations Aliados Station 58
Cut & Cover Stations Lima Station Cut & Cover Stations S. Bento Station 59
Cut & Cover Stations Water table lowering during excavation Settlements due to water table lowering were reduced (historic cyclic and seasonal variations) There was a significant gain in the soil stiffness and strength Working conditions were more favourable In any case, it was impossible to excavate without a bottom protection and guarantying that no water lowering would occur Cut & Cover Stations Water table lowering during excavation 60
Cut & Cover Stations Sequential Excavation Method Marquês Station Cut & Cover Stations Sequential Excavation Method Salgueiros Station 61
Cut & Cover Stations Sequential Excavation Method Bolhão Station Cut & Cover Stations Sequential Excavation Method 62
Cut & Cover Stations Sequential Excavation Method Phase 0 Phase 1 Phase 2 2,0m 2,0m NF Phase 3 2,0m Phase 4 Phase 0 Surface preparation, water table lowering and cap beam construction Phase 1 Partial or total excavation of the first ring Phase 2 Shotcrete of the first ring Phase 3 till Final Phase Sucesive excavation of aring ollowed by immediate shotcreting until reaching the bottom of the excavation Last but one Phase Final Phase Raio H=20m Cut & Cover Stations Sequential Excavation Method 63
Cut & Cover Stations Salgueiros Station Cut & Cover Stations Salgueiros Station WP 15 WP 16 79.95 WP 2 WP 3 WP 14 WP 1 WP 4 0.60 R1.65 1.60 WP 5 38.27 25.40 Primary lining Final lining WP 13 WP 6 Well Points WP 12 WP 7 WP 11 WP 10 WP 9 WP 8 6.60 3.60 2.00 0.30 0.45 12.02 2.45 28.09 0.60 0.60 64
Cut & Cover stations Cut & Cover stations 65
Cut & Cover stations Cut & Cover stations 66
Mining stations MINING STATIONS Mining stations Lima Station Marquês Station 67
Mining stations Heroísmo Station Faria Guimarães station Mining stations Bolhão station 68
Mining stations Drainage during construction Final design support is Functionally watertight Several excavation phases Excavation in soil Lattice girder were adopted Excavation was performed generally under the protection of an umbrella formed by horizontal jet-grouting In Faria Guimarães face reinforcement was adopted Mining stations 69
Mining stations Heroísmo Station Mining stations Faria Guimarães Station 70
Mining stations Faria Guimarães Station Mining stations Faria Guimarães Station 71
Mining stations Heroísmo station Mining stations Heroísmo station 72
Mining stations Lima station sttion Mining stations Lima station 73
Mining stations Lima station Mining stations Lima station 74
Mining stations Marquês station Mining stations Bolhão station 75
Mining stations Bolhão station Mining stations Bolhão station 76
Mining stations Bolhão station Mining stations Bolhão station 77
Mining stations Faria Guimarães station Mining stations Faria Guimarães station 78
Mining stations Faria Guimarães station Mining stations Faria Guimarães station 79
Mining stations Faria Guimarães station Mining stations 10 mm 20 mm 30 mm 40 mm Faria Guimarães station 80
Mining stations TBM information Estação Lima Heroísmo Section (m 2 ) 62,8 62,8 Cover(m) 15 18 Maximum Settlment(mm) 9,3 8,1 Volume loss (%) 0,36 0,36 Inflexion point (m) 9,74 11,24 Mining stations NATM excavations Estação Heroísmo Marquês Section (m 2 ) 232 182 Cover(m) 13 18 Maximum Settlment(mm) 9,5 19,4 Volume loss (%) 0,32 0,49 Inflexion point (m) 14,7 18,2 81
Mining stations -50 NATM excavations Ajuste de Gauss - Marquês Distância ao eixo túnel (m) -40-30 -20-10 0 10 20 30 40 50 0 sentamento (mm) Ass 5 10 15 5 10 15 5 10 15 20 Medições Ajuste 20 20 Mining stations NATM excavations Rua de Faria Guimarães/Rua de Fonseca Cardoso - Lado Este Perfil longitudinal de assentamentos (alvos automáticos) 5,0 1596 A2.1 1597 15981599 1599 A2.1 A2.1A1.1 A2.1 1601 A1.1 1601 A2.1 1603 1602 A1.1 A1.1 1602 A2.1 1623 1624 A3.1 A1.1 Galeria Cais 1625 A1.1 1625 1626 A2.1 A1.1 1628 A1.1 1629 1629 A1.1 A2.1 1681 A1.1 Assentamento (mm) -5,0-15,0-25,0-35,0 Poço Faria Guimarães Poço Fonseca Cardoso -45,0-55,0-65,0 04/02/04 16/02/04 01/03/04 16/03/04 29/03/04 12/04/04 29/04/04 17/05/04 26/05/04 31/05/04 07/06/04 14/06/04 21/06/04 28/06/04 05/07/04 12/07/04 19/07/04 26/07/04 02/08/04 82
Acknowledgments: Metro do Porto and Normetro; Prof. Luís Ribeiro e Sousa; Prof. Paul Marinos; Dr. Siegmund Babendererde. OBRIGADO PELA VOSSA ATENÇÃO! THANK YOU FOR YOUR ATTENTION! António Viana da Fonseca & António Topa Gomes @ FEUP 2010Jornadas TÚNELES Y EXCAVACIONES EN GRANITO Abril 2010 83