1. Alpine Fault Scenario EQ
QC Project
FP2 Research 1

2. Alpine Fault Scenario – FP2 research
Damage indices (LSN)
ESA
CHC
Failure
ALPINE FAULT
SITE EFFECTS
(LOCAL SOIL CONDITIONS) 2

3. Two Approaches Simplified analysis (conventional engineering tool)
Advanced analysis (top-end research / eng. Tool)
Input required: PGA contour maps (FP1)
Output: LIQ damage maps (indicators of liquefaction- induced damage to land, buildings and infrastructure, in generic terms)  in absolute terms and relative to CES
Input required: Acceleration time history (FP1)
Output: Acc. TH, response spectra, detailed soil and site response, dynamic animations (disp. & PWP)  an extension to FP1 GM simulations
LSN – damage maps 3

4. SIMPLIFIED METHOD: Input – PGA contours4

5. SIMPLIFIED METHOD: over 20,000 CPTs
Area based 5

6. SIMPLIFIED METHOD: Output
Damage Index Maps (e.g. LSN map) 6

7. The Liquefaction Ground Damage Model
Moderate to Severe
Liquefaction land damage (LSN)
Minor to Moderate
None to Minor
Multiple CPT (or SPT) in the area indicate some spatial variability. Some areas have more spatial variability than others. Depends on geological processes that laid down the sediment.
Increasing earthquake shaking (PGA)
A different set of curves for each area

8. The Liquefaction Ground Damage Model
A different set of curves for each area due to:
Soil composition
Soil density
Depth to groundwater
Spatial variability
Top set of curves are in an area of dense beach sands whereas the bottom set of graphs is for fine loose easturine deposited soils

9. The Liquefaction Ground Damage Model
Shaking

10. The Building Foundation Differential Settlement Model
Ground damage
Shaking
Liquefaction land damage (LSN)
Building Foundation Differential Settlement
None to Minor
Minor to Moderate
Moderate to Severe
95 %ile
85 %ile
50 %ile
Based on building differential settlement survey data obtained from buildings affected by the CES
CES = Canterbury Earthquake Sequence
These curves apply to light weight houses with shallow foundation systems with either concrete slabs or perimeter concrete ring beam (typically 300mm wide by 600mm high) supporting a timber floor with internal short posts nominally embedded 200 to 300mm into the ground.
15 %ile
5 %ile

11. The Building Foundation Differential Settlement Model
Ground damage
Foundation damage
Shaking

12. The Building Loss Ratio Model
Ground damage
Foundation damage
Shaking
Building Foundation Differential Settlement
Building Loss Ratio
Type C
Type B
Building Loss Ratio = Building repair cost / building value (or replacement cost). So a value of 1 = total loss and a value of 0.1 = $30,000 damage to a $300,000 house.
Type C = 100mm thick concrete slab foundation
Type B = perimeter concrete ring beam (typically 300mm wide by 600mm high) supporting a timber floor with internal short posts nominally embedded 200 to 300mm into the ground
TC3 = stiff / robust foundation system - either a 400mm thick waffle slab or timber floor with deeper joists – such that any differential settlement from liquefaction results in planar (i.e. flexure) movement only.
Policy dependent. In NZ replacement policies are “as good as new” means typically > 50mm of differential settlement results in requirement to relevel. The repair costs depending on the type of foundation system used.
The building loss model has to be locally adapted for local construction typology and also policy
Based on building damage repair costs obtained from buildings affected by the CES
TC3

13. The Building Loss Model
Ground damage
Foundation damage
Financial loss
Shaking
A different set of curves for each area due to:
Soil composition
Soil density
Depth to groundwater
Spatial variability
Based on building differential settlement survey data obtained from buildings affected by the CES
Based on building damage repair costs obtained from buildings affected by the CES

14. Model outputs for a given MW and PGA
15th percentile
50th percentile
85th percentile
M7; 0.3g
M7; 0.7g

15. The Liquefaction Module Framework
Ground damage
Foundation damage
Financial loss
Shaking
Pipe damage ?

16. ADVANCED ANALYSIS: 55 Christchurch Sites16

17. Representative Soil Profiles
YY1 profile
NN2 profile 17

18. Numerical Models 18

19. Effective Stress Analyses (1/2)
Acceleration TH
EPWP TH 19

20. Effective Stress Analyses (2/2)20

21. OUTPUT Simplified analysis (conventional engineering tool)
Advanced analysis (top-end research / eng. Tool)
LIQ damage maps (LSN, LPI, etc.) - indicators of liquefaction-induced damage to land
LIQ-induced damage to buildings and infrastructure, in generic terms)  through ‘vulnerability/fragility relationships
AF-induced damage relative to CES
Acc. TH, response spectra,
Detailed soil and site response (in absolute terms and relative to CES)
Dynamic animations (disp. & PWP)  an extension to FP1 GM simulations
LSN – damage maps 21