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1 PLEASE DOWNLOAD THE FULL PRESENTATION AT NEXT: CALLS FOR TENDERS HISTORY BENCHMARKING: THE GOTTHARD TUNNEL TELT: WHO WE ARE THE PROJECT

2 GEOLOGICAL FRAMEWORK The Lyon Turin Base Tunnel crosses the Alps from West to East intersecting several geological zones. Lyon-Turin

3 GEOLOGICAL OVERVIEW Mont Cenis Base Tunnel: 57,5 Km under the Alps These geological zones are not clearly separated as they are the result of multiple geological phenomena occurred over the past 100 million years, which also explains for the geological complexity of the region.

4 GEOLOGICAL OVERVIEW How the Alps were formed The Alps arose as a result of the collision of the African and European tectonic plates, in which the western part of the Tethys Ocean, that was formerly in between these continents, disappeared. THE GEOLOGICAL COMPLEXITY OF THE MONT CENIS BASE TUNNEL AREA DEPENDS ON THE ORIGIN OF THE ALPS

5 GEOLOGICAL OVERVIEW Geological Uncertainties about the project ABOUT GEOLOGY Presence of faults Zones difficult to be investigated Anisotropy ABOUT HYDROGEOLOGY Water bearing layer Water circulation Natural Heat Risk of karst phenomena ABOUT GEOTECHNICS Heterogeneity of the formation High Overburdens Z. Ultra-dauphinoise Z. Sub-briançonnaise Z. Houillère briançonnaise Z. briançonnaise centrale Soubassement Z. piémontaise Socle briançonnais Massif d Ambin Z. piémontaise

6 SUMMARY OF COMPLETED SURVEYS Kind of surveys Total TOTAL AMOUNT LENGHT (km) AMOUNT LENGHT (km) AMOUNT LENGHT (km) AMOUNT LENGHT (km) FOR EACH KM (57 km) Traditional Surveys 69 10, , , ,3 Directional Surveys ,8 1,0 Vertical seismic profile 6 3, , , ,1 2,3 Seismic Excavation Profiling ,6 1,5 Survey shafts ,04 Exploratory Tunnel 2 2,4 4 13,5 => 27,0 4 16,0 => 29,4 5 16,0 => 29,4 0,3 => 0,5 NOT INCLUDING WINZES AND COMPLETED WORKS SURVEY ,1 km SEISMIC ,7 km

7 SUMMARY OF COMPLETED SURVEYS Access adits and Exploratory Tunnels Tunnel SMP4 Saint-Martin-La-Porte La Praz (2 400 m m ongoing) (2 480 m) => à terme Villarodin-Bourget/Modane (4 036 m) La Maddalena m Works Saint Martin la Porte COMPLETED ACTION Investigation of the «Houillère Briançonnaise» Zone : coalfield area with schists rocks La Praz Villarodin-Bourget / Modane La Maddalena Knowledge of the East Houillère Briançonnaise Zone and water inflows Confirmation of right safety station site. Tests for treatment of excavated material. Investigation of Ambin Massif with high topographic overburdens

8 LA MADDALENA EXPLORATORY TUNNEL MILAN La Maddalena site TURIN Il Cunicolo Geognostico della Maddalena 4

9 The exploratory tunnel of La Maddalena in Chiomonte Excavated Portion 7 KM Plan of the Gallery Worksite Deposit Full lenght 7597 m Start of construction works April 16 th 2012 Start of the excavations January 2013 Phase 1 excavations D&B (jan 2013 jull 2013) 198 m Phase of istallation TBM (august 2013 oct 2013) Phase 2 excavations TBM (from 2013) 7000 m MODANE

10 LA MADDALENA site (Chiomonte) is in the Italian region Piedmont close to Turin (Northern Italy) LA MADDALENA EXPLORATORY TUNNEL History : Start of excavations Jan-Jul 2013: Phase 1 traditional excavation : Phase 2 excavation wirh TBM 2012: Start of construction works 2011: Building of the construction site 5

11 LA MADDALENA EXPLORATORY TUNNEL Objectives of the study Investigation of the Ambin Massif. Use of mechanized excavation (the three tunnels on the French side were completed with conventional methods). Excavation under the highest overburden expected (greater than 2,000 m).

12 LA MADDALENA EXPORATORY TUNNEL Method of excavation FIRST 200 M WITH TRADITIONAL TUNNELLING TECHNOLOGY m WITH TUNNEL BORING MACHINE THE GLACIOFLUVIAL DEPOSITS AND CARBONATE SCHIST ROCKS METODO MECCANIZZATO con TBM aperta 9

13 LA MADDALENA EXPORATORY TUNNEL TBM technical sheet Beam ROBBINS TIPO Main Beam 6,30 m diameter cutters 7 motors 315 kw Being unshielded, the main beam TBM allowed direct observation of the rock face along the alignment, an important advantage considering the main scope of the tunnel, which was of geological and geomechanical investigation. 11

14 LA MADDALENA EXPORATORY TUNNEL Rock Mass Conditions 0 m > 200 m Approximately 100 m of tunnel were excavated in the glaciofluvial deposits, soils with a silty matrix containing blocks. In these soils, tunnelling took place by mechanical excavation under a steel umbrella arch over the tunnel crown and behind fibreglass reinforcement beyond the tunnel face. sci do gi ca THE INITIAL 200 M GROUND CONDITIONS WERE UNSUITABLE FOR MAIN BEAM TBM. fg 12

15 LA MADDALENA EXPORATORY TUNNEL Rock Mass Conditions 200 m < m Starting from chainage excavation took place only in the formations of the domed structure of the Ambin Massif. More specifically: up to ch aplitic gneiss of the Ambin Complex (AMC) from ch and up to the transition zone (AMD) from ch to the end of the tunnel alignment, grey mica schist and minute gneiss of the Clarea Complex (CL) Cl AMD AMC

16 LA MADDALENA EXPORATORY TUNNEL Hydrogeological Conditions THE RECORDED VALUES WERE LOWER THAN THE EXPECTED MINIMUM AND MAXIMUM STABLE INFLOWS. ESTIMATED FLOW RATE MEASURED FLOW RATE Only dry Quaternaty Deposits were crossed and no karst conduits were intercepted in the Hydrogeological Unit 1 (Carniole). Water inflow began only at ch when the Hydrogeological Unit 5 (Gneiss and Micaschists) was crossed by excavation. 13

17 LA MADDALENA EXPORATORY TUNNEL Rock Mass Quality The rock mass was of excellent quality, with RMR (Bieniawski 1989 [1]) reaching 98, but very abrasive, strong (250 MPa uniaxial compressive strength) and hard. 6% (RMR I class) excellent quality 6% I 1% IV 42% (RMR II class ) 42% good quality II 51% (RMR 51 % III class) III medium quality 15

18 LA MADDALENA EXPORATORY TUNNEL Spalling and rockburst problems encountered over m In December 2015 at km 4.2 the most evident episode of rockburst occurred. The rock mass experienced a sudden brittle failure at tunnel crown and invert with a depth of damage (development of fractures) of m, which produced bulking behind supports and bending of the steel ribs for a tunnel length of m. There was no important release of kinetic energy and the event is to be considered of mild rockburst known as BULKING WITHOUT EJECTION 16

19 LA MADDALENA EXPORATORY TUNNEL Lesson Learned The level of knowledge relating to the Ambin Massif has increased. Pont Ventoux Tunnel Reaching an exceptionally high 2,000 m, rockburst remained mild, with dilatant fracturing, but without evident release of kinetic energy. Confirmation of TBM method Maddalena Base Tunnel Clarea Maddalena Base Tunnel 18

20 SAINT-MARTIN-LA-PORTE

21 SAINT-MARTIN-LA-PORTE History: : Phase 1 SAINT-MARTIN-LA- PORTE area is in the French region Savoy (Southern France) 2007: Villarodin- Bourget Winze completed 2009: La Praz Winze Completed 2010: SMLP Winze completed 2015: Phase 2: excavation with TBM and completion of the access to the base tunnel 5

22 SAINT-MARTIN-LA-PORTE Overall view 3a 3b 1 Exploratory Tunnel 2 Completed Ongoing 4 Saint Martin la Porte 9 km TBM EXCAVATION La Praz FromTBM the early 2015 to the present: Part 3a: new inclined access adit Part 1 TMB assembly room Part 3b: part of the South-Tube of the Base Tunnel through the so-called productive coalfield by conventional methods in order to reach the future base tunnel alignment. Part 4 TBM dismantling room Part 2 Ongoing excavation along the base tunnel alignment

23 SAINT-MARTIN-LA-PORTE Objectives of the study Check and improve the available geological and geomechanical models. Gain insights into conventional versus mechanized (TBM) excavation of the Base Tunnel. Understand the response in difficult conditions, in particular in the Carboniferous Formation. Identify potential karst zones and underwater flow around the Base Tunnel. Test different products for waterproofing/improvement of the ground in problematic zones.

24 SAINT-MARTIN-LA-PORTE Method of excavation: TBM «Federica» The TMB used to excavate this gallery was designed to cope with the particular geological constraints of the zone. Built in France, by NFM Technologies du Creusot (Saône-et-Loire), it has a cutting head of metres in diameter and 76 cutting disks, and a power output of 5 megawatts, the equivalent of eight F1 engines. The TBM advances on average 350 metres/month.

25 SAINT-MARTIN-LA-PORTE Saint-Martin-La-Porte access adit The excavation of the Saint Martin La Porte access adit started in March 2003 with a design length of about 2000 m and was completed at the end of m 10 m

26 SAINT-MARTIN-LA-PORTE Saint-Martin-La-Porte access adit: Difficulties Experienced Following the large convergences occurred between chainage 1200 and 1550 m, the alignment of the tunnel initially chosen was modified. The intent was to better accommodate the rock mass anisotropic conditions encountered and the junction with the Base Tunnel. The Briançonnaise zone is characterised by the presence of coal and sandstone. In some places, the rock mass is intersected by water bearing faulted geological features.

27 SAINT-MARTIN-LA-PORTE Saint-Martin-La-Porte access adit: Phases of excavation FRONT ZONE INTERMEDIATE ZONE CREEP ZONE DISTANCE FROM THE TUNNEL FACE: Face pre-reinforcement 0 m m m m m FLEXIBLE RETAINING STRUCTURES SEMI-RIGID RETAINING STRUCTURES CAST-IN-SITU LINING PHASE 1 Phase 2-25 m Phase 3-80 m

28 SAINT-MARTIN-LA-PORTE La Praz access adit Hydrogeological characterization: m: water inflows > 15 l s Base tunnel level: low flows (<5l/s) =>Test of Consolidation Treatment through Injections of Expanding Resins => Permeability reduction and protection of water resources => Base tunnel geological section up to date (2008)

29 SAINT-MARTIN-LA-PORTE Exploratory Tunnel Difficulties Experienced After 300m of excavation Federica met benches of sandstones of metric thickness with fractures (intercalated with schists) provoking the separation of blocks to the front and the progression of the cutter; the ribbon conveyor has not been able in some points to evacuate some blocks of great dimension. These elements caused the stop of the TBM for some days.

30 SAINT-MARTIN-LA-PORTE Exploratory Tunnel Solutions Injections of poliuretanic foam expansive in front of the tunnel face to cover the voids Injections of bi-component resin to consolidate the material core Boring works This case is a CLEAR EXAMPLE OF THE EXPLORATORY TUNNEL IMPORTANCE.

31 SAINT-MARTIN-LA-PORTE Lesson Learned The level of knowledge of the so called the Carboniferous Formation, Zone Houillère Briançonnaise-Unité des Encombres has increased. Confirmation of the innovative yielding support system implemented with a near circular cross section Confirmation of TBM method 18