christchurch town hall for performing arts post earthquake and foundation repair assessment august...
TRANSCRIPT
Christchurch Town Hall for Performing ArtsPost earthquake and foundation repair assessment
August 2013
22 February 2011 – what happened??
Design approach…
• Engineers are expected to design structures for two main states:– Serviceability Limit State (SLS) - buildings are
designed so that they suffer very little or no damage;– Ultimate Limit State (ULS) – buildings remain
standing; people are able to safely leave the building. The building may be seriously damaged.
• 100% NBS = 100% of New Building Standard (Code)
Geotechnical investigation location plan
Generalised subsurface profile (Section 1)
Lenses liquefiable in ULS event
Lenses liquefiable in SLS event, Liquefiable in ULS event
Lenses liquefiable in ULS event
What can we do to repair the building foundations??
• Narrowed down to two proposed options:– Preferred option Jet grout columns with a thick concrete raft slab; or,
– Alternative option Large diameter bored piles around the perimeter of
the buildings with small diameter micropiles beneath the complex.
• An experienced specialist sub-contractor to the main contractor is required.
Seismic Performance
Jet Grout Piles
Liquefaction in ULS event
Less over the soil layers
More in each soil layer
Lateral spreading Approx. 50mm 75 to 150mm
Differential settlement
Total 100mm 30mm
Differential 75mm 30mm
Jet Grout columns with thick concrete raft slab
Source: WAM (Aug 2013) Christchurch Town Hall – CCC Workshop Final Report (Rev A)
Jet Grout columns with thick concrete raft slab
Source: WAM (Aug 2013) Christchurch Town Hall – CCC Workshop Final Report (Rev A)
Jet Grout columns with thick concrete raft slab
• NZ experience:– Jet grout operations beneath a several buildings in
Christchurch has been undertaken. Details are not available due to insurance/ building owners preference.
• Worldwide experience:– A number of existing buildings, gas and oil tank facilities
have had jet grout columns installed underneath themeg San Francisco Museum of Modern Art ($365 Million
upgrade project)
END