LAGUNA at Fréjus LAGUNA/LAGUNA-LBNO General Meeting March 3 th -5 th, 2011, CERN Eng. Francesco Amberg

LAGUNA at Fréjus – General Meeting, CERN, March 2011 >1700 m rock overburden LSM Underground Laboratory Modane Railway tunnel ( ) Current situation – General plan view Longitudinl section 6,2 km 12.8 km 6,6 km Road tunnel ( )

LAGUNA at Fréjus – General Meeting, CERN, March 2011 External LSM building Current situation - LSM underground laboratory Modane km 6.0km 7.0 6,2 km6,6 km A cavity of about 3500 m 3 in the middle of Fréjus Road Tunnel in french territory

LAGUNA at Fréjus – General Meeting, CERN, March 2011 New safety tunnel LSM Underground Laboratory Modane Cross connection Safety tunnel (currently under construction, expected conclusion 2014)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Location of new detector near existing infrastructure LSM (1982) Safety tunnel (2009 – under construction) Road tunnel (1974 – 1978) New detector (example with MEMPHYS)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Geology Trias Series Calcareous schists

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Assessment of rock mass properties - Usual situation (a priori) Laboratory tests Intact rock properties Modulus of elasticityE=50 GPa Poisson’s ratio =0.2 Density  =2.7 t/m 3 Compressive strength  ci =100 MPa Properties of discontinuities Friction angle  =35/23° Cohesionc=150/15 kPa Number ? Orientation ? Empirical methods Rock mass properties highly uncertain

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Assessment of rock mass properties – Situation at Frejus (a posteriori) In situ large scale tests Modulus of elasticityE din =15 GPa Compressive strength  ci =15/4 MPa Others properties Water inflow Rock mass temperature Back analysis Rock mass properties Intensive analysis of tunnel behaviour during construction (and well documented) Excavation of road tunnel Convergence monitoring Extension of failure zone around tunnel Discontinuities (number, orientation, quality) Advantage of Frejus Reduction of uncertainties

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Back analysis of road tunnel (time-dependent behaviour) Definition of time dependent parameters: Short term:from tunnel behaviour 35 m behind the face (5 days) rock support provided only by systematic bolting (convergence 6-9 cm) Medium term:from convergence before casting of final lining at a distance of round 500 m behind the face (70 days) (convergence cm) Long term:from pressure acting on lining after 25 years (radial pressure t/m 2 )

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Geotechnical parameters of rock mass Unit weight 27 kN/m3 Elastic modulus 15 GPa Poisson’s ratio 0.2 Friction angle 35/40°(lower/mean value) Peak cohesion 3000 kPa Residual cohesion 2000 kPa(short term) kPa(medium term) kPa(long term) Plastic strain 0.5 %(for reach residual cohesion) Dilation angle 3°

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Main characteristics of calc-schists Time-dependent behaviour of rock mass (displacements) Tendency to wedge instability on roof Anisotropy of rock mass properties (effect of schistosity) Reduction of rock mass strength after failure No water circulation in the rock mass (OK for cavern stability and thermal losses during reservoir operation)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Earthquake hazard potential in EU Frejus Low hazard

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Type of detector to receive Volume of excavation: GLACIER: 160'000 m 3 LENA: 111'000 m 3 MEMPHYS: 838'000 m 3 (3 caverns)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LAGUNA – Largest man-made excavation  Empirical designs methods not reliable (no experience)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Basic principles – Displacements Radial displacement (δ r ) ~ Excavation radius (R) Plastic radius (R pl ) ~ Excavation radius (R) R R pl δrδr Road tunnel : R=6.1 m,δ r =10 cm Memphys :R=33.5 m  δ r =55 cm

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Basic principles – Effect of gravity Wedge pressure (p) ~ Excavation radius (R) Bolt length ~ Excavation radius (R)  Support per m 2 ~ R 2 (also for lining) R p Road tunnel : R=6.1 m,lining d=50 cm Memphys :R=33.5 m  lining d=2.7 m

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Analysis of wedge stability

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Analysis of displacements - 3D model (FLAC)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Displacements – Short term

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Failure zone – Short term

LAGUNA at Fréjus – General Meeting, CERN, March 2011 GLACIER – Final lining Thickness: 1.5 m (roof and vertical wall)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LENA – Final lining Thickness: 0.7 m (roof and vertical wall) In vertical walls to be installed proceeding bottom-up Thickness of the lower part (20 m) increased to 1.2 m

LAGUNA at Fréjus – General Meeting, CERN, March 2011 MEMPHYS – Final lining Thickness: 1.5 m (roof and vertical wall), 2.3 m in the lower part (15 m)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Geomechanical feasibility GLACIER, LENA and MEMPHYS option are feasible at Fréjus site. The overall stability of the cavern is assured. A support is however required for wedge stability. The geomechanical feasibility remains valid also by a small change of the size of the excavation, both in the diameter and height of the cavern. The geomechanical conditions at Frejus are well known and further investigations are basically not required. The safety tunnel under construction will provide further information. The support system proposed guarantees the long term stability and the absence of significant time dependent displacement of the cavity. The support system proposed has sufficient reserve to ensure the stability of the cavern in case of earthquake.

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Mechanical interaction with rock (MEMPHYS) FREE TANK TANK IN CONTACT WITH ROCK TOP THICKNESS 1.0 cm BOTTOM THICKNESS 15.7 cm1.0 cm STEEL MASS 11‘170 kg3‘970 kg

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Steel tank in contact with rock mass The rock loads are supported by the concrete lining and will not be transferred on the steel tank. The water from the rock mass can cause an external load on the imperious tank (even if apparently the rock is dry). To avoid this type of load, it is necessary to design an external drainage system. The earthquake is not a problem for the steel tank, if there is not an active fault crossing the cavern (atypical situation).

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Thermal interaction with rock (MEMPHYS) Solution with the insulationSolution without the insulation ROCK: T = 30°C WATER:T = 13°C HEAT ENERGY TRANSFER (Q)

LAGUNA at Fréjus – General Meeting, CERN, March 2011 GLACIER

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LENA

LAGUNA at Fréjus – General Meeting, CERN, March 2011 MEMPHYS

LAGUNA at Fréjus – General Meeting, CERN, March 2011 GLACIER Sec.ItemCost 1Main detector 33.4 M€ 2Access galleries 6.3 M€ 3Auxiliary caverns 0.9 M€ 4Site infrastructures 20.3 M€ 5Engineering, safety costs 6.1 M€ TOTAL 66.8 M€ Cost per m 3 (315'000 m 3 ):~210 €/ m 3

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LENA Sec.ItemCost 1Main detector 12.0 M€ 2Access galleries 5.3 M€ 3Auxiliary caverns 0.9 M€ 4Site infrastructures 9.1 M€ 5Engineering, safety costs 2.7 M€ TOTAL 30.0 M€ Cost per m 3 (142'000 m 3 ):~210 €/ m 3

LAGUNA at Fréjus – General Meeting, CERN, March 2011 MEMPHYS Sec.ItemCost 1Main detector 90.4 M€ 2Access galleries 9.5 M€ 3Auxiliary caverns 1.1 M€ 4Site infrastructures 50.5 M€ 5Engineering, safety costs 15.2 M€ TOTAL M€ Cost per m 3 (911'000 m 3 ):~180 €/ m 3

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Technical feasibility – Tank construction Unit cost reaches 180 – 210 €/ m 3 ; Fréjus safety tunnel: 310 €/ m 3. The solution with tank placed in contact with the rock mass is feasible at Fréjus site for LENA and MEMPHYS option. For GLACIER option an independent tank is preferable. The solution with tank placed in contact with the rock mass can save the amount of steel needed (7‘200 kg for MEMPHYS option, 3‘600 kg for LENA option). Both the solution with the insulation and without insulation are feasible at Fréjus site.

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LAGUNA-LBNO at Frejus – Option 1 Same volume as MEMPHYS option with 3 tanks but cost reduction of 11.5 M€ for excavation and support

LAGUNA at Fréjus – General Meeting, CERN, March 2011 LAGUNA-LBNO at Frejus – Option 2 Excavation and support of additional LENA costs only 23 M€

LAGUNA at Fréjus – General Meeting, CERN, March 2011 General conclusions for Frejus The Frejus site allows to host all the detectors options proposed within LAGUNA, i.e. GLACIER, LENA and MEMPHYS. The rock mass behavior was deeply investigated (during highway tunnel and now safety tunnel) allowing to minimize the uncertainties and the risks related to the realization of further underground cavities. The excellent quality of the rock, with the appropriate amount of plasticity, allows the excavation of very large cavities at a depth of 4800 m w.e., which is the deepest in Europe (for an underground laboratory). The Fréjus safety tunnel, presently under construction, provides an optimal and completely safe access to the site during both construction and operation (whole life-time, e.g. 50 years). The Frejus rescue team, permanently in service, ensure the highest safety support both in the tunnel and in the laboratory. The accessibility of the Frejus site is excellent (by road or train from many international cities as Torino, Chambery, Lyon, Genève, Milano, Paris).

LAGUNA at Fréjus – General Meeting, CERN, March 2011 THANK YOU FOR YOUR ATTENTION

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Graphic layout

LAGUNA at Fréjus – General Meeting, CERN, March 2011 Graphic layout