2015/7/22

1

「リスク共生から見た地盤工学上の課題」

地盤工学の新たなる課題とモニタリングの重要性

ケンブリッジ大学、横浜国立大

曽我健一

社会インフラストラクチャーリスク共生、イギリスでは。。。

• 外貨獲得のためのインフラ開発

• データに基づいた政策決定

• Building Information Modellingの活用

• リスクベースの維持管理

• 工学的知識を活用したモニタリング

Establishment of

“Infrastructure UK” in 2010

From 2010 to 2014

トンネル！

National Infrastructure Plan

• “High quality infrastructure is essential for supporting

productivity growth. Delivering the right infrastructure at

a local, regional and national level, across the UK, is […]

key to the government’s long-term economic plan.”

• £466B (90兆円）for the next generation of infrastructure

by 2020

• 2,500 different projects

• A step-change in the nation’s approach to infrastructure

investment.

• An export potential for an international market that is

valued at least $57 trillion (5700兆円）in the period up

to 2030.

118 km from east to west

37 stations

9 new stations (8 sub-surface)

Increase London's rail-network

capacity by 10%

Crossrail – New London Underground Line in London Industrial Strategy (2013)

過大設計安全率の神話化

品質向上

建設材を少なく。 他にない地盤工学

2015/7/22

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UK Infrastructure - Risk

• The cost to the nation of inadequate infrastructure is estimated to be in

the order £2M per day or $0.75B per year.

• For extreme events, direct costs can be in the £100Ms per incident.

• National economic infrastructure is largely privatized and sectorally

divided.

• As foreign investment in infrastructure systems and networks

increases, trans-national corporate governance priorities may also

come into conflict with these national hierarchies, with fiscal and

political consequences.

Evidence base decision making

Building Information Modelling

London Underground

Victoria Station UpgradeBuilding Information Modelling

(courtesy Mott MacDonald)

D B

11

Tottenham Court Road (TCR)-STATION UPGRADE PROJECT

Northern Line

Central Line

Source: Halcrow

新しいインフラと古いインフラ

• 新しいインフラ– 建設および維持管理を安く

– 本当のパフォーマンスとは。

– Observational method

– 長期モニタリング、そして劣化モデルの構築

• 古いインフラ– 実際の挙動を示したデータが必要

– 他のシステムとの相互作用から検討

– 劣化モデルの構築

2015/7/22

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Observational Method

UK Design Codes - Soil Strength Parameters

mo

de

rate

ly c

on

se

rva

tiv

e

Soil Strength Parameter Results

No

of

Re

ad

ing

s

1 in 21 in 201 in 1000

Mo

st

Pro

ba

ble

Ch

ara

cte

ris

tic

ma

teri

al

pro

pe

rty

(us

ed

in

str

uc

tura

l e

ng

ine

eri

ng

)

Mo

st

Un

fav

ou

rab

le

(Eg Undrained strength, SPT etc)

PeckPeck EC

EC

14

15

CIRIA (1999) Report 185 - Nicholson, Tse and Penny

Goals

• Clarify OM definition and process

• Integrate OM process into modern design

• Focus on “Ab Initio” applications – better planning

15

Ideal EC7 Predicted versus Measured Performance

No

. o

f re

ad

ing

s

Deflection ( )

"Ideal" distribution of

measured deflections

Predicted EC7

Characteristic

Value (SLS)

5%

Predicted most

probable value

Most

Unfavourable(ULS)

16

Ideal EC7 Predicted versus Measured Performance

No

. o

f re

ad

ing

s

Deflection ( )

"Ideal" distribution of

measured deflections

Predicted EC7

Characteristic

Value (SLS)

5%

Predicted most

probable value

GREENAMBER

RED

Most

Unfavourable(ULS)

Trigger

implement

17 18

CIRIA (1999) Fig 3.13 Multi Stage Excavation

18

2015/7/22

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CIRIA (1999) R185 Figure 1.2

The OM Process

21

Monitoring Dashboard Data Interpretation Optimisation - DashboardsNorthern Line Monitoring at Liverpool Street Station

Monitored Section of the Royal Mail Tunnel

Crossrail – Liverpool Street Station – C510

Monitored SectionCrossrail

Platform

Tunnel

Excavation

Bloomfield

Box

Excavation

After Crossrail

How Big Is It?

≈ 2.74 m

≈11 m

≈6 m

Constructed: 1917 - 1923

Suspended: 2003

Made of cast iron

2015/7/22

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Tunnelling Induced Greenfield Settlements

Smax

Longitudinal Settlement

Longitudinal Strain

Tension

Compression

(After Attewell, 1986)

Bending

Mode

Shear

Mode

After Devriendt

Shear LPDT Orientation

Expected settlement profile

New

Tunnel

Compressive (-ve) when ring nearest

tunnelling approach shifts downward

with respect to neighbouring ring!

Data for these sensors

above sign reversed in

data processing.

Layout of Sensors & Location of

Sensors 11, 34-40

Data presented

2881

@ Node 11

2940

@ Node 40

29.5m

New Tunne

l

120 Wireless Sensors to monitor

movements of 60 joints

Wilcock

Pilot tunnel

Main tunnel

2015/7/22

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百聞は一見に如かず

The ‘Smart Tunnel’

A building

construction at the

Isle of Dog,

London

Loizos Pelecanos

36 Pile load testing – current trends and innovative monitoring

River Terrace Deposits

Lambeth Group

Thanet Sand

Chalk

Made Ground / Alluvium

Large diameter piles - 2.4m dia.

Very deep - avoid tunnels

( 25m into Chalk)

LU tunnel

Thick raft span over tunnels

LU tunnel

2015/7/22

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Reinforcement

cage

1

2

43

NFibre optic

cable cluster

Regiment 2

O-Cell

Regiment 1

Pile

Typical SectionElevation

BOTDR analyser• Distance range ≈10-30km• Readout resolution = 0.05m• Gauge length resolution = 0.2-1m• Strain Resolution = 10-30me

Distributed Brillouin Sensing

Providing “Continuous Strain Profile”

Layer 1

Layer 2

O-Cell

PileLoad distribution

Compression

Friction

DownUp

2015/7/22

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Integrated FO

distributed strain

and can provide

distributed values

of vertical

displacement

This shows the

evolution of vertical

displacement with

applied load at

every point along

the pile depth

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

0 0.01 0.02 0.03 0.04

Ele

va

tio

n [

m]

Vertical displacement, u [m]

Vertical Displacement Profiles

P=0

P=1.78MN

P=3.64MN

P=5.92MN

P=6.93MN

P=8.58MN

P=10.53MN

P=12.21MN

P=13.72MN

P=15.51MN

P=17.29MN

P=18.94MN

P=20.51MN

P=22.43MN

P=23.94MN

P=25.56MN

Load (MN)

Dis

pla

cem

ent

(mm

)

Load (MN)

Load (MN)

Dis

pla

cem

ent

(mm

)

Load (MN)

Load (MN)

Dis

pla

cem

ent

(mm

)

Load (MN)

Top of O-cells

Level 2

Level 3

Level 4

Level 5

Level 6(highest)

Fibre optic integrated strain

Extensometers

Displacements are relative to the top of the pile

Small displacement

Very small displacement

Fibre optic displacement

from integration of strain

Good agreement between

fibre optic and

extensometers for all

levels, even for small

displacements at higher

levels

• Split soil into 4 layers:

> Layer 1: Made Ground

> Layer 2: Sandy Silty Clay

> Layer 3: Thanet Sand

> Layer 4: Chalk

• Calculate:

(a) Shaft Friction

(b) Vertical Displacements

48

Further post-processing:

49

-50

0

50

100

150

200

0 0.005 0.01 0.015 0.02 0.025 0.03

Shaf

t Fr

icti

on

, SF

[kP

a]

Displacement, z [m]

1. Made Groundc31

c32

c41

c42

0

20

40

60

80

100

120

140

160

180

200

0 0.005 0.01 0.015 0.02 0.025 0.03

Shaf

t Fr

icti

on

, SF

[kP

a]

Displacement, z [m]

2. Sandy Silty Clay

0

20

40

60

80

100

120

140

160

180

200

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Shaf

t Fr

icti

on

, SF

[kP

a]

Displacement, z [m]

3. Thanet Sand

-800

-600

-400

-200

0

200

400

600

0 0.01 0.02 0.03 0.04

Shaf

t Ft

icti

on

, SF

[kP

a]

Displacement, z [m]

4. Chalk

Image Source: Pile Dynamics and National Highway Institute

PROBLEMS WITH PILE CONSTRUCTION

Construction can be challenging – alignment, concrete quality and placement, soil collapse

Visible inspection not possible

Repair and rework is very difficult

Not all anomalies are defects/detrimental

2015/7/22

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-5

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Tem

per

atur

e C

han

ge (°C

)

Days

DFOS temperature over time at 15m depth (-8.7 mOD)

mOD) T-1-1 Green

T-2-1 Orange

-5

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Tem

per

atur

e C

han

ge (°C

)

Days

DFOS temperature over time at 35m depth (-28.7 mOD)

T-1-1 Green

T-2-1 Orange

TEMPERATURE AT A GIVEN DEPTH OVER TIME

DIFFERENTIAL TEMPERATURE AT 14 HOURS

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5

-5 0 5 10 15 20 25

Dept

h (m

OD

)

Temperature Change ( C)

14 Hours (Heating)

T-4-1T-3-1T-2-1T-1-1O-Cell

1

2

43

Cooler

Warmer

N

1

2

43

Warmer

Cooler

Value =Product

(what it claims it will

do)

+Confidence

in delivery(do I believe it will work?)

Mission:

“Transform the future of infrastructure through smarter information”

Vision:• Enable step changes in construction practice• Establish a world-leading sensing and monitoring industry • Extend asset life & reduce management costs

An Innovation and Knowledge Centre

Funded by EPSRC and Innovate UK

17 Million pounds investment for five years from UK government and Industry

Consultants, contractors and asset managers

Technology and information supply chain

Knowledge partners

Infrastructure Clients(Owners and Operators)

2015/7/22

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Field demonstrations & case studiesExamples of Monitoring Applications

Piles

Examples of Monitoring Applications

Masonry Arches

Lee Tunnel, Abbey Mills, Stratford – Shaft F

Winner of the 2013 Fleming Award: MVB JV, CH2M Hill, AECOM, Bachy Soletanche, Underground

Professional Services, University of Cambridge, Mott MacDonald, WJ Groundwater and ESi

2015/7/22

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Examples of Monitoring ApplicationsTunnels

社会インフラストラクチャー

• インフラストラクチャーの社会の役割。

• データに基づいた意志決定、Building Information

Modellingの活用。

• Observational Methodなどリスクを考慮した設計、施工、維持管理。

• 工学的知識を活用したモニタリング。その中での地盤工学者の役割。