lausanne metro tunnel collapse 2005 james mcmulkin, claire rose, ashley rogers
TRANSCRIPT
Lausanne Metro Tunnel Collapse 2005
James McMulkin, Claire Rose, Ashley Rogers
Lausanne
Lausanne
Lausanne Metro
Foreland
Basin
/
Molasse
Deposit
Foreland Basin/Molasse Deposit
Moraine
Umbrella Vault NATM
22nd February 2005
Earlier in the day• In rush of water
from the moraine layer led to work stopping
• Investigations were being carried out by the contractor for Lot 1200 to determine the cause
18:00 MET• Tunnel collapse
occurred• 50m3 entered the
tunnel• Large crater below
Rue Saint Laurent
What Water?
Engineering Solutions for Specific Problem:Identifying Problem
• Improving soil strength should have been essential to allow for safe tunnelling
Engineering Solutions for Specific Problem:Solving the Problem
Actual Solution After Collapse
• Collapsed void first reinforced by 11 drilled piles (CFA likely) and grouting
• 800m³ of crushed glass sand used as infill due to good compactability
• Slope design changed due to need to go deeper