Management of Ageing London UG Tunnels___new Techno to Old Bds

7/30/2019 Management of Ageing London UG Tunnels___new Techno to Old Bds

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Management of ageingLondon Underground tunnels:

-Applying new technologies to old problems

Peter Wright

Tube Lines


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Who are Tube Lines?

Infrastructure consortium responsible for the

Jubilee, Northern and Piccadilly Lines.

PPP Contract over 30 years to improve

London's Underground system.

Required to improve knowledge and

understanding of deep tube tunnels, which

were in an uncertain condition (grey).

In practice over 200km of tunnels and shafts

have to be structurally assessed.

Also required to make grey assets safe


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Typical conditions

in deep tubes


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City and South LondonRailway

First cast iron tube railway completed in 1889 From King William Street to Stockwell

Completed in 4 miles in 4 years

Compressed air working, Greathead shield, JH Greathead was the

engineer

Original concept cable-hauled but changed toelectric power

Not a single life lost


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The Greathead Shield


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Compressed Air Working


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The Padded Cells


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Northern Line

Tunnel expansionin

1920s


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11ft 8.25 CI Lining


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A closer look ata tunnel length..

Stn Stn

Distorted rings

Cross passage opening,

cross passage

Cracked segments

Ventilation opening

Pump sump

Disused station Shield chamber Cross tunnelVarying separation,

but normally less

than 1 diameter


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Generic studies

Investigate on a global basis, rather thanasset specific, wherever possible

Apply results of these studies

Examples:- Lining circularity

- Cast iron lining thickness & strength

- Geotechnical parameters


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20. Databases

and other

software

21. Exemplar

Assessments

22. Guidance

on Overall

AssessmentProcedure

Future

Amendments

to LULStandards

3. M/N

interaction

diagramsfor CI and

calculation

of safety

factors

4.Investigation

of Failure

Mechanisms

5. Soil

Parameters

and their

variation

16. CI

deterioration

mechanisms

and

degradation

model

10. Concrete

Tunnel Lining

durability and

residual life

assessments

15. Defects

model for CI

rings14. Defects

model for

Concrete rings

2. In situ stress

measurement

in CI and

Concrete

11. FE model

of CI joints

17. Study of

Historical

Construction

methods

18. Study of

Bomb

locations

19. Adoption

of suitable FE

and other

software

13. Grey CI

transverse

stress

research

1.Development

of In situ stress

measurement

techniques in CIand Concrete

12. Investigation

of non-

destructive

testing methods

6. Study of

Radar and

other

geophysical

methods

K & P Projects Concept

JNP tunnel assessment manual & toolkit

8. Supplementary

investigations

7. Critical

Situations

and

Parameter

Sensitivity

9. Adatptation of

Totaline or expert

system for

assessment


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Inspection/Assessment

Options

Factors Affecting

Failure Behaviour

Failure

Behaviour

So What?

How will

the FailureHappen?

What are the

Engineering Factors

that Influence Failure?

What Tools are

(or could be)

Available?

How Good?Mature?

Linkage?

Significance?Confidence?

Development

Consequence


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Expanded

Bolted

Existing Damage

Manufacturing Quality

Visual Immediate

Complete

CollapseMaterial Quality

Significance?

Build Quality

Water

Acid ity

Voids Outside Tunnel

External Contamination

Outside Party Works

Internal Environment

Component Degradation

Other Structure Proximity

EMC/Electrical Discharge

Openings

Partial

Collapse

Distortion

Safety

Related

Impact

Survey (Depth/Circularity)

Radar

Ultrasonics

Core Sampling

Electro-Magnetic

In Situ Stress Analysis

Desk Top Study

Confidence?

Inspection/Assessment

Options

Factors Affecting

Failure Behaviour

Failure

Behaviour

Consequence

100030050620

100030050

620

1000

30050620


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Tunnel Analysis & Design

1. Elastic ContinuumMethod

Morgan, Muir Wood,Curtis, Peck, Arends etc

We use TOTALINE

program (Curtis full

bond).


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Geotechnical FE

Long term

deformed mesh

LH tunnel

constructed

first

Initial, long term

squat = -1mm, 6mmGround loss at

excavation = 1.93%first tunnel, 1.69%

second tunnel


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Stresses along

tunnel axis range

from

54MPa in tension

to41 MPa in compression

3Dstructural

FE


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Looking at invert,with LH segment

removed

3D structural FE


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Coring and ultrasonics ingrey cast iron


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Position of Coring & Ultasonic Inspection Results

NORTHBOUND RUNNING TUNNEL: Position of cores relative to each other (in all cases):

R1930 R1940 R3260

23.12 23.33 21.91 22.94 24.30 23.00

27.45 27.60 22.57 24.05 26.00 24.77

27.05 27.45 23.80 23.58 27.70 27.80

R3241 NORTHBOUND SOUTHBOUND

Average measured thickness of core:

R1930 22.88 mm

19.10 20.20 R1940 20.10 mm

20.20 20.75 R3260 25.08 mm

21.77 24.60 R3241 20.38 mm

DIRECTION

OF RUNNING

DIRECTION

OF RUNNING

Typical coring andultrasonic readings


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Grey cast iron strengthtesting


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Grey cast iron strength

testing


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Grey cast iron strength testing


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CPT and soil testing


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Circularity measurement

Best-fit Perfect Circle

Circularity Survey Data

Deformation exaggerated x 10

Estimated Centre

Typical circularity

measurement,showing approx

1% squat

Circularity carried

out using Leica

3000 track trolley


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-2.0

-1.0

0.0

1.0

2.0

860

900

940

980

1020

1060

1100

1140

1180

1220

1260

1300

1340

1380

1420

1460

1500

1540

1580

1620

1660

1700

1740

1780

1820

1860

1900

1940

1980

2020

2060

2100

2140

Northbound Ring Number

%ooc(squat+ve

-2.0

-1.0

0.0

1.0

2.0

1280

1320

1360

1400

1440

1480

1520

1560

1600

1640

1680

1720

1760

1800

1840

1880

1920

1960

2000

2040

2080

2120

2160

2200

2240

2280

2320

2360

2400

2440

2480

2520

2560

Southbound Ring Number

Circularity measurement

Typical longitudinal plot showing tunnel

deformations between Golders Green and

Hampstead


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Direct Stress Measurement


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ACSM - StressProbe


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Basics of Stressprobe

Stress in a material causes changes in magnetic

domain behaviour The altered domain distribution causes changes

in the permeability of the material

Stressprobe measures the changes inpermeability using an induced magnetic field andpickup coils

Often a demag cycle is needed to removemagnetic hysteresis


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ACSM - StressProbe

Stress

across CIpan

(N/mm2)

Hoop Load

adjacent toOpening


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Summary of AssessmentWork Tunnel assessment work now nearly complete

Tube Lines Tunnels team have used a combinationof in house and external expertise to carry out

Analysis

Investigation

Inspection Assessment

Reporting

Classification

Risk Assessment and Remediation Inspection

Further Analysis

Monitoring and Survey

Strengthening


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Openings in Tunnels

Support by lintel and bolts


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Covent Garden

BOLTS SHEARED

SEGMENT PUSHING FORWARD BY 30mm

FRACTURE NOTE TO LINTEL

LINTEL COMPRESSING & DISTORTING

GENERAL VIEW

LINTEL ENDS

COMPRESSED &

DISTORTED

30mm PUSH INWARD TO

SEGMENT & BOLTS ARE

SHEARED.

SEGMENTS FRACTURED

FRACTURE TO EDGE OF

SEGMENT


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EustonPhotographs

GENERAL VIEW

MANY BOLTS MISSINGAROUND THE OPENING

LINTEL COMPRESSEDAND DISTORTED

BRAKE DUST BUILD UP

HAS FALLEN OF APOTENTIAL REASON MAY

BE LINTEL MOVEMENT

APPARENT SHEAR

MISS-ALIGNEDSEGMENTS

LINTEL BUCKLING


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Acid attack

at

Old Street


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Acid attack at Old Street


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Cracked Lining

atOld Street


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Acid attack

at

Bond St?


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Outside Party Developments


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Expanded ConcreteLiningsSignificant face spalling of segments


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BOTDR Monitoring

Photo No. 4-

5

Protection of

the Cable

Fibre Optics Strain Measurement


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Fibre Optics Strain Measurement


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Average strain over 1m every 5cmRange ~5-10km

Resolution 30 (0.003%)Low cost sensors - optical fibre

5 - 25 minutes per measurement

Can link or switch between fibres


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Monitoring of existing ThamesLink tunnel

Tunnelling obliquely under Victorian masonry tunnel

Existing tunnel loaded by canal basin retaining wall

Directly below Midlands Main Line (MML)

MML

above

Existing

ThamesLin

k tunnel

Canal basin

New tunnelReproduced from Ordnance Survey of Northern Ireland mapping with the

permission of the Director and Chief Executive, Crown Copyright.

3.6m

6.5m

8.5m

Thameslink Tunnel at KingThameslink Tunnel at Kings Crosss Cross


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Underground M3Aims of the project

Develop

Micro-detection - computer vision Micro-monitoring - MEMS sensors (Micro-electro-

mechanical systems)

Micro-communication Wireless communication

and power harvesting Data analysis and expert systems

Industry Application System Safety, adaptation and field application

Business Plan and Integration

http://www-civ.eng.cam.ac.uk/underground/index.html


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Tube Lines Role AssociatePartner

Attend quarterly meetings

Advice and guidance from an industry point of

view

Facilitate visits and pilot studies in our tunnels

Benefit from developments made by the

project


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Concluding Remarks

Increasing demand (Why?) for sensor

systems to monitor civil infrastructure? For

what purpose? To monitor structures with reduced/indeterminate assessed safety

factors, and, in connection with an Emergency PreparednessSystem, to prevent vehicles entering the danger area in the event

of failure.

To monitor structures where new construction works affect existing

infrastructure, and in connection... Ditto

As part of a temporary works system to control and reduce theeffects of construction movements

To better understand the behaviour of structures to improve

assessment accuracy.


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Management of Ageing London UG Tunnels___new Techno to Old Bds

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