Design of Segmental Lining for Waterview

Project, Auckland (NZ)

R. Mahajan, A. Kuras, S. Pradhan Parsons Brinckerhoff, Australia

Well-Connected Alliance – Waterview Connection

Content • Project overview • Geotechnical conditions • Key features of lining • Overview of design approach • Cam-pocket system design • Cross passage opening design • Performance • Conclusions

Well-Connected Alliance – Waterview Connection

Project Overview Overview

• Location - Auckland (NZ)

• Project Cost - NZ$1.4b

• Project Objective - Complete western ring route

• Project Model - Alliance (NZTA client)

• Delivery by - Well-Connected Alliance

• Tunnel Construction - Commenced 2013

• Commissioning - April, 2017

Tunnel (key elements)

• TBM - 10th largest EPBM machine

• Diameter - 14m (largest tunnel in Australia-Pacific)

• Reinforcement - World’s largest SFRC lining

Well-Connected Alliance – Waterview Connection

Geological Long-Section

Soil

Rock

Typical Su =50-250 kPa

Typical UCS EU1= <1 MPa EU2= 1- 5 MPa EU3= >5 MPa Vb=50-150 MPa

South Portal North Portal

Note- gradient exaggerated for illustration purpose

2

1

3

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Key Lining Features • Segmentation

9+1 key segment

450mm thick lining and 2m wide rings

3 types of ring (L, R and S) with 30mm taper

• Circumferential connection

3 spear bolt connections per segment

28 nos. of shear cams at spear bolts locations

• Longitudinal connection

2 spear bolt connections per joint

Total of 20 spear bolts per ring

• Reinforcement

3 types of reinforcement

Combination of SFRC and RCC segments

• Waterproofing

EPDM gaskets

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Layout

38.570

39.420

28 Shear cams & Spear bolts

Standard Segment

2 spear bolts

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Design Approach Optioneering

• Ring configuration - ‘8+1’ vs ‘9+1’

• Concept of cam pocket system ?

• Number of thrust rams

• Method of reinforcement

• Connectors- spear bolts vs dowels

Stage Lining design steps

1 Lining configuration and geometry assessment

2 Construction phase assessment

3 Structural capacity assessment

4 Waterproofing assessment

5 Stability assessment

6 Earthquake assessment

7 Fire assessment

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Analytical Assessment • Traditional closed form solution approach • 2D coupled bedded beam approach • 3D coupled plate element approach

2D beam spring model 3D plate element model

birdmouthing

Rigid Link

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SFRC Design Strengths • Minimum characteristic flexural strength (peak) target = 4.8 MPa

• Minimum characteristic residual flexural strength target = 3.0 MPa

• Minimum characteristic indirect tensile strength target = 3.8 MPa

Beam test (bending) Cylinder test (splitting)

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Segment Reinforcement

Well-Connected Alliance – Waterview Connection

Cam-Pocket System

Cams Pockets

Well-Connected Alliance – Waterview Connection

Why Proposed? Introduced to restrict differential ring deformation along section under

GNR (~8m cover) by creating structural interlock

Aids with minimising lipping and stepping during construction

providing greater surety of watertightness

Well-Connected Alliance – Waterview Connection

Cam Configuration

350

150

30

Profile

Clearance

5mm vertical clearance on inclined face & 2mm horizontal clearance

Takes account of lipping, birdmouthing of longitudinal joint & packing of

circumferential joint

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Analytical Assessment Capacity

2D/3D FEM results compared with past testing

2D FEM calculated failure load of 282kN

3D FEM calculated failure load of 400kN

Testing results suggest failure load of ~500kN 2D FEM

Testing

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XP Opening

Lintel Beam

Jambs

Vertical Wedges

Sill Beam

Connection

Vertical Stiffeners

Horizontal Stiffeners

Horizontal Wedges

Skin Plate

Rigid connection

Temporary Panels

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XP Optioneering • Configuration

• Circumferential connections

• Durability / Fire protection

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Steel Opening Canopy tubes

grouting tubes

Vertical wedge

Horizontal wedges

Temporary panels

1

2

3

4

5

6

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Lining Performance • Minimal stepping/ lipping between segments

• Tunnel generally dry • High tensile capacity of SFRC results in few cracks

observed for Type 1 segments

• 95% SB tunnel completed

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Conclusions • Success of lining design hinges on communication

between design and construction teams • Leverage off the experiences of Obayashi technical

department has proven to be invaluable • Optimisation of design relies on applying a range of

analytical methods • SFRC proven for large diameter tunnels • Cam pocket system introduces benefits

Well-Connected Alliance – Waterview Connection

Thank You