Download 7535.0-090331-Rewiew Munich

General meeting LAGUNA
LAGUNA – Fréjus site
Geotechnical feasability
(Rewiew of WP2 Munich January 26th-27th, 2009)
March 30th.- April 2nd 2009, Wroclaw
CURRENT SITUATION: GENERAL PLAN
LSM Underground Laboratory Modane
G4
Centrale C
Usine C
Railway tunnel
LAGUNA Fréjus Site
Longitudinal section
>1500 m
rock overburden
6,6 km
6,2 km
12.8 km
12.8
68
km
G5
PHT 17
PHT 15
G3
(LSM)
PHT 11
C en G 2
tr
Usin ale B
eB
PHT 9
PH
T5
PHT
3
Road tunnel
G1
LAGUNA Fréjus Site
Geotechnical parameters of rock mass
• Unit weight
27 kN/m3
• Elastic modulus
15 GPa
• Poisson’s ratio
0.2
• Friction angle
35/40°
• Peak cohesion
3000 kPa
• Residual cohesion
2000 kPa
(short term)
500-750 kPa
(medium term)
200-300 kPa
(long term)
• Plastic strain
0.5 %
(for reach residual cohesion)
• Dilation angle
3°
(lower/mean value)
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)
LAGUNA Fréjus Site
• Reduction of rock mass strength after failure
• No water circulation in the rock mass (OK for cavern stability
and thermal losses during reservoir operation)
Cavern design
GLACIER
320'000 m3
MEMPHYS
558'000 m3
41.9
D=67 m
70 m
D=76 m
19 m
47.5
25 m
D=35 m
110 m
LAGUNA Fréjus Site
21.9
17 m
9m
LENA
221'000 m3
LAGUNA Fréjus Site
Memphys – 3D model (FLAC)
LAGUNA Fréjus Site
Memphys – Displacements – Long term
LAGUNA Fréjus Site
Memphys – Failure zone – Long term
LAGUNA Fréjus Site
Memphys – Analysis of wedge stability
Large excavations at Frejus - Conclusions
• The construction of the large excavations for the 3 detector
types of Laguna is feasible at Frejus site.
• For Glacier it is possible to built a unique large tank. The division into
2 smaller tanks can reduce the total construction costs of the caverns.
• For Lena it is not necessary to have curved walls
LAGUNA Fréjus Site
• The final lining should be placed at least 2-3 months after the excavation
in order to reduce the rock pressure in the long term (excavation from
top to bottom, construction of final lining from bottom to top).
Interaction between tank and rock mass
• The stability of the rock mass during excavation is ensured by anchors and reinforced
shotcrete
• The definitive cavern is sustained by a concrete lining.
•Glacier needs a inner, independent tank.
•The rock loads are supported by the concrete lining and will not be
transferred on the steel tank.
LAGUNA Fréjus Site
•The water from the rock mass can cause an external load on the
imperious tank (even if apparently the rock appears 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).
Location LAGUNA
Safety tunnel
LAGUNA Fréjus Site
Road tunnel
LAGUNA
Railway tunnel
LAYOUT (top view)
Access Tunnel
Electronics
Safety
Tunnel
Electronics
Electronics
Road Tunnel
LAGUNA Fréjus Site
Air and
water
purification
Control
room,
offices,
storage,
power
LAYOUT (side view)
Road Tunnel
Air and
water
purification
Safety
Tunnel
Electronics
LAGUNA Fréjus Site
Access Tunnel
Control
room,
offices,
storage,
power
Electronics
LAYOUT
Safety
Tunnel
Air and
water
purification
Control
room
Electronics
Electronics
Storage
LAGUNA Fréjus Site
Electronics