FHI 32: FCC tunnel layout and transferline update Tuesday, 9 February 2016 CE Updates: Comparison of 100km Intersecting and Non-Intersecting options New interpretation of geology C. Cook (SMB), J. Osborne (SMB), Intersecting Non-Intersecting GADZ interpretations - Prealps GADZ interpretations - Voirons GADZ interpretations - Vuache GADZ interpretations - Jura Intersecting Intersecting - New Non-Intersecting Non-Intersecting - New Amberg Report Geological and Geotechnical conditions Risks applicable to FCC options. Basis of 5. and 6. First look at excavation methods for tunnel, shafts and caverns based on varying geological conditions Comparison of options Introduction and description of options Conclusion 3. Geological conditions 4. Handling main geological hazards Ground water Ground water in moraines unknown, boreholes to be used, shaft excavation methods vary (d-walls, piles) Tunnel: Pressure of water in fault zones too high, solution is to use sealing injection umbrellas around tunnel Tunnelling through Moraines Risk that moraine under Lake Geneva and Rhone is deeper than predicted => exploration boreholes, Tunnel Boring Machine (TBM) waterproof up to 20bar Karsts Probes ahead of tunnel to search for Karsts, fill karsts with concrete, mortar or cement. Drainage for karsts filled with water Hydrocarbons Prealpes, Jura and Mandallaz highest risk. Qualified expert (geologist/engineer specialising in natural gas explosions) Rock squeezing Highest risk in Prealpes due to high overburden and possible weaker rock => drill & blast (not TBM) recommended for these tunnel sections 5. Excavation methods Tunnel Molasse TBM best adapted & least expensive method Work rates of 600m/month seem realistic 22 months for an (averaged) 11km section between two points (2 mths for maintenance) Extra 15 months should be allowed between signing TBM contract & beginning of excavation Limestone (Jura, Mandallaz & Prealpes) Drill & blast method recommended Higher flexibility to react to rock squeezing, heavy water inflows, karsts and gas Good conditions 10-12m/day ( m/month) Drill & blast fronts from both sides not too dissimilar in speed to single TBM drive over the same distance Drill & blast team (google images) 5. Excavation methods Experimental Caverns Excavation sequence based on good geological conditions (stable rock) Support: rock bolts, lattice girders and reinforced shotcrete 5. Excavation methods Experimental Caverns Excavation sequence based on moderate geological conditions (Flysch and soft clay rock) Support: micro piles, rock bolts, lattice girders and reinforced shotcrete 5. Excavation methods Experimental Caverns 5. Excavation methods Service and access caverns Service Caverns with a span of 20 m and Access Caverns with a span of 15 m excavated like the Experimental Caverns in partial sections (see subchapter 5.2.1). An important point for planning the location of the Service Cavern is the stability of the rock pillar between Experimental Cavern and Service Cavern (see Figure 29). This rock pillar has to transfer the additional burden of half of the two caverns and has to be probably 40 to 50 m wide. The necessary dimension can be determined only after exploring the geological conditions in this area. 5. Excavation methods Experimental Shafts If moraines is firm, cohesive or consolidated => conventional excavation. Lattice girder rings, shotcrete and steel mesh as support If loose or below water table => pile walls up to 25m deep, diaphragm walls >25m Through moraine layer Through molasse layer Drill & blast recommended. Support similar to moraines but less required 5. Excavation methods Access Shafts Excavation through moraines is the same as for the experimental shaft. For the molasse, shaft boring machines or drill and blast are possible. Drill & blast may prove the less risky choice (flexibility, previous projects failed with machine, non-specialised workfoce). 6. Comparison of FCC options Data 6. Comparison of FCC options Data 6. Comparison of FCC options Conclusion A shaft to shaft analysis of the two FCC 100 km options has been carried out and is based on the two longitudinal sections attached in the Appendices 1 and 2 It can be concluded that the foreseen caverns and shafts, with their proposed dimensions, are possible to excavate under the given geological circumstances it will become more a question of time and costs than constructability. neither engineering nor logistic limits are met although special equipment with limited availability is needed for certain structures. With the information available so far, no changes of the project, with respect to the given dimensions for shafts and caverns, are mandatory. it is strongly recommended to execute further geological and geotechnical investigations. Based on the results of these investigations, additional risks can be detected or currently defined risks can be adjusted for each option. A final recommendation of one of the two options is very difficult to make at this stage of the project and would lead to a premature decision based on insufficient data. However, if a decision had to be made by CERN at this stage based purely on the available data, the Intersecting Option would seem the better choice due to the avoidance of the Flysch section in the Pr-Alps with high overburden and squeezing potential. In addition, for this option, the excavation of the Experimental and Access Points are assumed to lie entirely in Moraine and Molasse with good rock conditions." Note: CE recommendation remains 93km Option 1. This was outside the scope for Ambergs report FCC Schematic - Single Comments from FHI? 6m diameter FCC Schematic - Twin Comments from FHI? 4.5m diameter Access Shaft PM54 12m diameter Access Shaft Concept double lift Diameter tbc Pressurised Stairwell Main lift (pressurised) Backup lift (pressurised) Access Shaft Concept magnet shaft Oblong, dimensions TBC Main lift (pressurised) Trmie Pressurised Stairwell