North American Chinese Geotechnical Engineers Association - 8th Geotechnical Workshop

A-Level Los Angeles Room, Los Angeles Department of Water and Power

Friday September 9, 2011

Seismic Design Approach for Large Counterfort Wall Retaining Structures

Andy Dodds

Senior Geotechnical Engineer

2

• Arup

• Seismic Design Approach for Large Counterfort

Wall Retaining Structures

Outline

Outline of Presentation

3

• Ove Arup, a Danish engineer, started the practice bearing his name in 1946, at the age of 51, and is most often remembered as the structural engineer for the Sydney Opera House.

The W’s

• Arup is a global design and consulting firm, organized into three main business practices:

Buildings,

Infrastructure, and

Consulting.

90 Offices Worldwide

Who is Arup?

What and Where is Arup?

4

International, national and local.

Some Arup Projects

5 Presentation

Seismic Design Approach for Large

Counterfort Wall Retaining Structures

Co-authors:

Philip Davies, BEng (Hons), MSc, DIC, CPEng, MIEAust

James McIlquham, BEng (Hons), CEng, CPEng, MICE, MIEAust Golder Associates, Sydney, Australia

6

N

Existing

Port Botany Site

Port Botany

Expansion

Sydney Airport

Third Runway

1km

NSW

Australia

Project Location

Location

7 Plan View

Site

8 Oblique View

Site Works

9 Oblique View of Completed Works

Completed

Works

Boat Ramp

Bridge, Road,

Services and

Foreshore

Enhancement Works

Dredging

PBE Expansion

Counterfort

Units

10 Counterfort Retaining Structure

Counterfort Unit (~

65

ft)

11 Cross-Section

Typical Section

12 Cross Section

Dredging and Filling

13 Longitudinal Section

N

Existing

Port Botany

Site

Port Botany

Expansion

Sydney

Airport

Third Runway

1k

m

Foundation Conditions

14 Oblique View

Berth Structure

15 Static and Pseudostatic Loading

Design Loadings

16 Global Bearing Capacity

Bearing (Shear) Mode of Failure?

17 Numerical Modeling

Dynamic Finite Element Modeling

18 Numerical Modeling

Dynamic Results

19 Dynamic Model Movement

Dynamic Results

20 Pseudostatic Considerations

Pseudostatic versus Dynamic

)(tFkxxcxm

Dynamic: An

Idealized

System

Time (t)

Pseudostatic:

FPGA ?

PGA

Acceleration

Earthquake

F

21 Newmark Model

Newmark Sliding Block

• Predominantly translational mode of movement noted in dynamic model

• Self-stabilizing nature will promote translational tendencies

22 Validation

50% PGA Validation

0

100

200

300

400

500

600

700

800

900

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Slid

ing

Blo

ck D

isp

lace

me

nt (

mm

)

Threshold Acceleration / PGA

EQ1

EQ2 - 227 degree component

EQ2 - 137 degree component

EQ3

Displacement of

dynamic model

23 Findings

Messages

• Limit equilibrium is limited!

• Justify a reduction in PGA when undertaking a pseudostatic design approach.

24 Sitewide

General View

25 Sitewide

General View

26 Circular Precast Yard

Counterfort Precast Yard

27 Precast Yard

Counterfort Falsework

28 Precast Yard

Counterfort Falsework

29 Precast Yard

Counterfort Rotation

30 Movement on Land

Counterfort Transportation

31 Storage on Land

Counterfort Storage

32 Movement over Water

Counterfort Crane Barge

33 Movement over Water

Lifting Frame

34 Placement

Placing Counterfort Units

35 Reclamation

Reclamation by Pipe Discharge

36 Ground Improvement

Land Vibrocompaction

37 Ground Improvement

Underwater Vibrocompaction

38 Ground Improvement

Dynamic Compaction

39 Ground Improvement

Dynamic Compaction

40 Happy Friday

Thanks.