Route Goward and Septum 16 shielding increase LS

Route Goward and Septum 16 shielding increase LS 1 Committee - 21 st - 20 September 2013 L. A. Lopez Hernandez

• The shie. Iding increase of the PS over Route Goward passage and over Straight Section 16 was proposed by RP, recommended by the PSRWG, presented at the IEFC and endorsed by the management • The cost of the intervention has been included in the PS‐LIU budget

Route Goward RP presentation from 59 th IEFC (S. Damjanovic) The extra-concrete shielding required following HSE recommendations was ~ + 180 cms.

Proposed solution: Concrete slab 2 m thick Piling wall protecting the tunnel from the load of the road

Works carried out: -Earthworks -Temporary road to give limited access to the center of the ring during the construction works -Piles -Concrete slab 2 m thick -New road ~ 100 m long, including retaining walls, backfilling, modification of the existing networks, etc Schedule: Currently: -Road open -Works finished on schedule

Some pictures of the works: Temporary road Retaining wall Piling works

Formwork for the slab Biocofra Slab reinforcement

Concreting Backfilling Road works

Straight Section 16 RP presentation from 61 st IEFC (S. Damjanovic) The extra-concrete shielding required following HSE recommendations has been converted in earth shielding New max ground level: 442. 6 m (means between +1. 2 and +3. 4 m over the existing level)

Requested: - Additionnal depth of earth of between 1. 2 m and 3. 4 m depending of the area Constraints: - Existing structures not strong enough to take the additional load - Area with a very complex geometry (PS, Linac 2&3, Leir, TT 2, . . ) - Works must have no influence or impact on the existing structures

Feasibility studies:

Proposed solution : -A new load-bearing structure taking the weight of the additional earth and redirecting it into the bedrock underneath. -The structure consists of a 1. 10 m thick reinforced concrete slab and the additional depth of backfill will be placed directly on the slab. -The slab rests on drilled piles, or secant piles in areas subject to particularly heavy loads -In the places where the existing tunnels are made of large masses of concrete, the slab rests on intermittent supports on the tunnel roof

Bird’s eye view of the new slab:

- To protect the existing structures, the transfer slab must guarantee that even after long-term deformation the load-bearing relief structure does not under any circumstances come to rest on the existing structures. - To this end, the slab will rest on a biodegradable honeycomb cardboard formwork that can be dissolved with water. This procedure guarantees that, once water has been injected to dissolve the cardboard, a void of 10 cm remains after concreting, which is more than enough to allow for the long-term deformation of the slab

Biocofra:

Slab deformation: 56 mm 51 mm

Schedule Currently: -Piles finished -Concreting works starting

Worksite installations: Parking route Goward shared with CV Temporary spoil dump Concrete batching plant «Passage pieton» closed Access to building 561 (RP)

Monitoring of the existing structures -Photographic survey of the structures -Camera inspection of the drains ~ 300 m -Vibration measurements during piling works - Maximum particle velocity for historical buildings < 2 mm / s - Max value recorded: 1. 19 mm/s on sensor 2 - 3 D modeling of the (shielding + existing structures +ground) for prediction of displacements LS 1 Committee - 21 st L. A. Lopez Hernandez 19

Some pictures of the works:

Thank you for your attention