long-term effects of geotechnical processes - 北海道大 …€¦ · · 2014-08-25long-term...
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Long-term effects of geotechnical processes
Hokkaido University15 February 2005
Kenichi SogaReader in Geomechanics
Lunch Box (Bento)
• Appearance
• Price
• Expiration date
• Calorie
Geotechnical Construction
• Design
• Cost
• Sustainability/Maintenance
• Embodied Energy
Current
Source zone cleanup
Containment
Remediation
Plume restoration
Brownfield redevelopment
Maintenance & Reinforcement& Demolish
Design options• Construction – short period
– Design codes
• Maintenance – periodical, some uncertainty– Life-cycle cost analysis, system performance
• Long-term solution – rather slow. Large uncertainty. – Embodied energy evaluation, Life cycle environmental impact
analysis
Environmental solution/monitoring/maintenance
maintenance
Design options
construction Time
Future generation
Long-term consequences
Present stage
Resource management Protection Conservation
• Understand long term effects (geotechnical processes, embodied energy calculation)
• “Systematic” monitoring to deal with uncertainty in evaluating long-term effects
• Interpretation of data (direction and rate of change)
• Engineering ideas and solutions
Questions• Does the construction process affect the long-term
performance of geotechnical infrastructure?
• How much energy do we use to make a geotechnicalstructure? How much energy is used for its operation?
• What are the essential soil parameters and key indicators and how can we measure them?
• What long-term monitoring strategy should we adopt and at what scale?
• What are the emerging technologies that can be used for long-term monitoring?
Today’s Bento Menu
• Long-term effects of tunnel construction• Long-term effects of compensation
grouting• Long-term effects of piling• Innovation in monitoring
Case Study: CTRL
• CTRL contract 220 drive.
Tunnel Map Stratford to London St. Pancreas
Stratford Box
Breakdown of Tunnel Embodied Energy of CTRL 220 Construction
ConstructionEnergy
30%(266 GJ)
Material ProcessingEnergy
3%(30 TJ)
TransportationEnergy
2%(20 TJ)
Embodied Energyof Raw Materials
65%(584 TJ)
Equivalent CO2 Emission is 97.8 tonnes.
0.000059% of total UK greenhouse emissions in 2002
2.1% of all emissions associated with the UK construction industry in 1999.
Steel22%
Cement57%
Tail seal Grease5%
Aggregates3%
Sodium Silicate8%
Bentonite0%
Others5%
Aggregates*171%
Cement17%
Slag Cement1%
Bentonite1%
Others2%
Steel2%
Sodium Silicate2%
Pulverized fuel Ash4%
Total Mass
Embodied Energy
Comparison of the embodied energy of selected structures.
0.352,589,400[14]Large Office Building, 52 storeys, Australia, (130,000 m2)
1369,875[14]3 Storey Office,Australia (6500 m2)
1560,837[14]Large Shop, Australia (5918 m2)
3612,494[17]Single Storey Office, UK(584 m2)
3822,350[15]Standard Home, Toronto, Canada
7491,240[14]Residential attached two storey Unit, Australia (82 m2)
927942[16]Standard New US Home, Michigan, USA (227 m2)
1450625[13]Average House, Australia(125 m2)
2172414[12]Typical UK Masonry house (100m2)
1899,410[This project]CTRL, Stratford to London St. Pancreas Twin bore Tunnel
Embodied Energy(GJ)
Source ref.Building..
..EBuildingE
ETunnelE
1420
0
43 43
63
37
7
0
12
19
8
35
8.6 6.512 13
8.7
0
10
20
30
40
50
60
70
CTRL,Stratfordto London
St.PancreasTw in bore
Tunnel
Residentialtw o
storeyUnit,
Australia(82 m2)
SingleStoreyOffice,
UK, (584m2)
LargeShop,
Australia,(5918 m2)
3 StoreyOff ice,
Australia(6500 m2)
LargeOffice
Building,52
storeys,Australia,(130,000
m2)
Con
trib
utio
n to
Tot
al E
mbo
died
Eer
gy (%
%Contributionof Steel tototal E.E.
%Contributionof Cement tototal E.E.
%Contributionof DirectEnergy tototal E.E.
n
THE LONDON UNDERGROUND TUBE NETWORK
• Area served: 3240km2
• 45km N-S 72km E-W• line length: 392km• 35% (140km) in deep tunnels
• 80% (110km) cast iron• Deepest tunnel 67.4m bgl• Average tunnel depth 24.5m bgl• 2.5million passengers/ day
Existing Tunnels• New construction interactions
– pile driving nearby– neighbouring tunnel construction
• Long-term survival: what is the unexpired life?– chemical environment– earth and water pressures create ground loading – affected by construction, consolidation, creep, ageing– loads on lining must change as groundwater changes
• Design of new works– what ground actions to assume in what design life?– what influence from new construction activities?
LUL Kennington
R rotary cored boreholeP cable percussion
borehole
tunnel
3m 3m 1.5m 5m 10m
R2
4m
4m
4m
R1
LC1 LC6LC5LC4LC3LC2
P1P6P5P4P3P2
PM1 PM3PM2 EP1
North
LC self-boring load cell pressuremeter testsEP self-boring expansion pressuremeter testsPM self-boring permeameter tests
EPSRC / LUL Project• London northern line at Kennington
– 75 year old tunnel– ground investigation, in situ measurements, cores
• Piezometric conditions– pressure profiles, in situ self-boring permeameter– degree of drainage into tunnel
• Comparison of ground near and far from tunnel– lateral pressure; self-boring load cells and
pressuremeter tests– very high quality cores; stiffness, and strength
• Predicted response to rising ground-water– FE based on in situ conditions and trends
LUL Kennington stratigraphy
0 5 10 15 20
-56
-50
-44
-38
-32
-26
-20
-14
-8
-2R1
Made GroundRiver Terrace Deposits
London Clay Formation
Silty fine SANDLambeth Group
MUDSTONE/LIMESTONE
R2
Silty SAND
Fissured CLAYFlint GRAVEL
Silty fine SAND with Gravel
Upper Chalk
Thanet Sand
(m)
(m)
0
5
10
15
20
25
30
35
40
45
50
55
0 50 100 150 200 250 300 350 400Pore water pressure u: kPa
Dep
th d
: m b
gl
P1 P2 P3 P4 P5 P6 R1 R2
RIVER TERRACE DEPOSITS
LONDON CLAY
LAMBETH GROUP
THANET SAND
CHALK
L: Linear regression of borehole piezometer data in London Clay
H1: Theoretical hydrostatic profileWT @ 4.5m
H2: Borehole piezometer data in underlying granular strata showing hydrostatic distribution with WT @ approximately 16m
Tunnel position
Pore waterpressures
(R1)P1 P2 P5P4P3 P6
(R2)0
20
25
30
15
10
50
45
40
35
5
-3.0 0 3.0 4.5 9.5 19.5
Distance from tunnel centre line: m
Dep
th d
: m b
gl
T1
T3T4T2
T5
18
19
20
21
22
23
24
100 110 120 130 140 150
Pore water pressure u: kPa
Dep
th d
: m b
gl
Tunnel piezometer data
Linear regression of borehole piezometer data (line L Figure 5)
LUL Kennington: load cell data
0
100
400
300
200
cell 1
cell 4
cell 5
cell 6
cell 3
cell 2
Data expressed in kPa
Permeability
0
5
10
15
20
25
30
1.E-12 1.E-11 1.E-10 1.E-09 1.E-08Coefficient of horizontal permeability kh: m/s
Dep
th d
: m b
gl
PM1: 1m from tunnel liningPM2: 2.5m from tunnel liningPM3: 7.5m from tunnel lining
linear regression of PM1 data(closest to the tunnel lining)
Top of London Clay
Base of London Clay
Tunnel position
Field Permeability Measurement
Picture-1: Self-boring pressuremeter
L
D
Max. depthdrilled
Bottom of cuttingshoe after pullingback
Water filled cavity
Lateralflow
Vertical flow
Lower end ofmembrane
Long term effect of tunnel construction processes
Pore pressure
Horizontal displacementmeasurement points 4m and 16m
Instrument line
140m 120m
50m
40m
K0 = 1.5Water table 5 m below ground surfaceHydrostatic
St. James’s ParkDepth = 31mDiameter = 4.85m
Anisotropy
0
200
400
600
800
1000
1200
1400
1600
1800
0.001 0.01 0.1 1 10
Axial strain, ε a (%)
Norm
alis
ed s
ecan
t und
rain
ed Y
oung
's m
odul
us, E
u,se
c/p
o'
B-1
C-1
E-1 (Horizontally-cut)
Hight et al (1993)
•Similar pattern but different magnitude between 2D and 3D•Different pattern between isotropic and anisotropic soil because
of difference in stress path directions
0.00 10.00 20.00 30.00-340.00-320.00-300.00-280.00-260.00-240.00-220.00-200.00-180.00-160.00-140.00-120.00-100.00-80.00-60.00-40.00-20.000.00
-30.00 -20.00 -10.00 0.00-50.00
-40.00
-30.00
-20.00
-10.003D Isotropic 3D Anisotropic
Excess Pore Pressure Contour (kPa)
0
200
400
600
800
1000
1200
0 200 400 600 800
Mean effective stress (kPa)
( σa-σ
r) (k
Pa)
Vertically cut sample
Horizontally cut sample
0
200
400
600
800
1000
1200
0 200 400 600 800
Mean effective stress (kPa)
( σa-σ
r) (k
Pa)
Anisotropic model
Isotropic model
Undrained Effective stress paths
Excess pore pressure generations will be different
Long-term
0 days7.5 days26.4 days48 days590 days19 years
•Permeable tunnel lining leads to further settlement with time
•There will be slightly outward displacement around the tunnel
-8
-6
-4
-2
0
2
4
6
8
1 10 100 1000 10000 100000
Time after short-term (days)
Cha
nge
in d
iam
eter
(mm
) Horizontal diameter
Vertical diameter-8
-6
-4
-2
0
2
4
6
8
1 10 100 1000 10000 100000
Time after short-term (days)
Horizontal diameter
Vertical diameter
Anisotropic Isotropic
Performance of the tunnel lining
Performance of the tunnel lining
-700
-600
-500
-400
-300
-200
-100
01 10 100 1000 10000 100000
Time after short-term (days)
Hoo
p fo
rce
(kN
)
Springline
Crown
Anisotropic-600
-500
-400
-300
-200
-100
01 10 100 1000 10000 100000
Time after short-term (days)
Hoo
p fo
rce
(kN
)
Springline
Crown
Isotropic
Crown
Springline
145 7373145 198
145
145145145
145121
7373
73145 73
130145
14573
1457373
73141
7329
14514173
7373
68
7373
73
145
145
73
73
14573
145
145
145145
73
73
14573
14573
73
145145 145 145 145 145145 145145 73 97 73145 26145 127 73 BRIDGE STREET
JLE RUNNING TUNNEL
Sub
way
1
Speaker's Green
LLS.
c:\gcg\papers\harding\EPIS23.SRF
Grout Injections : Episode 2316 June 1997 to 20 June 1997
Scale 1:500
0m 10m 20m
Shaft 4/6
N
-10
0
10
20
30
40 Tilt
of Clock
Tower (
mm/55m
)
Nov-94 Nov-95 Nov-96 Nov-97 Nov-98 Nov-99 Nov-2000
Grouting Episodes
9 13 16 22 2531 35 39
WB EB WB EB
Tunnel Progress:Pilots Enlargements
Start ofGrouting
Box ExcavationProgress [m]:
ConstructionControlRange
Optical Plumb
May 27 June 13 June 17
45.5 m 17.5 mCase A Case B Case C
12.8 m
Shield tunnel20.0 m
3.5 m 7.0
m
Monitoring PointsInjection Points
Date of the tunnel face location
123
123
123
FillClayey siltFine sand
Alluvial clay 2
Sand
3 m
0 m
-10 m
-20 m
-30 m
Settlement Monitoring PointsSPT-N0 10 20
1
2
3 Alluvial clay 1
Alluvial clay 3
Alluvial clay 4
-20
-40
0
5 6 7 9Month
Dis
plac
emen
t mm
Tail passage
Grout injection (1)
-20
-40
0
5 6 7 9Month
Dis
plac
emen
t mm
Tail passage
(1)
Case A Case C
-20
-40
0
5 6 7 9Month
Dis
plac
emen
t mm
Tail passage
Grout injection(1)
Case B
-30
-20
-10
0
10
20
0 50 100 150
Time (days)
Set
tlem
ent (
mm
) Field dataFE data
-40
-30
-20
-10
0
10
20
0 50 100 150
Time (days)
Set
tlem
ent (
mm
) Field dataFE data
Case B
Case C
Drainage Hole
AppliedLoad
Piston withDrainage Holes
Clay Specimen
Porous Vyon Plate
Porous Vyon Plate
Copper Injection Needle
Drainage Plate
Cylindrical Casing(Brass or Steel)
Figure 4.3 Section of Modified Consolidometeri 4 3 S i f M difi d C lid
Note: Not to Scale
Different diameter specimens – simulate simultaneous injection at different spacings
Effect of OCR on Compensation EfficiencyGrouting Efficiency vs TV(R=25mm, epoxy injection)
-20%
0%
20%
40%
60%
80%
100%
120%
1 10 100 1000 10000 100000
Time (sec)
Gro
ut E
ffici
ency OCR=1
OCR=1.5OCR=2OCR=5OCR=10
Epoxy injection, R = 25 mm
OCR=1
OCR=1.5
OCR=2
OCR=5
OCR=10
Time (sec)
Gro
ut e
ffici
ency
100%
80%
120%
60%
40%
20%
0%
-20%
Very low efficiency in NC clays confirmed by field trials
Effect of Grout Spacing
100%
80%
60%
40%
20%
0%
-20%
-40%
-60%1
Fina
l Gro
ut E
ffici
ency
Closer spacing
OCR = 2
OCR = 1.5
OCR = 1
OCR = 5
2 3 4 5 6 7 8n
Single injection in infinite space
Similar FE results
Pile set-up - Field Observation
1
1.5
2
2.5
3
3.5
4
4.5
0.1 1 10 100 1000 100001
1.5
2
2.5
3
3.5
4
4.5
0.1 1 10 100 1000 10000Time (days)Time (days)
Pile capacity increase Qt/QtoShaft capacity increase Qs/Qso
• Driven piles in sand exhibit shaft capacity increases of typically 60% per log cycle time, though highly variable (20-170% per log cycle).
• Greater set up appears to occur in denser sands, with saturated and dry sands and not above 3m.
• References: Chow et al (1998), Jardine & Standing (1999)
Observation of soil movement during pile driving
Model pile is jacked into calibration chamber. Digital images captured through reinforced window.This example: silica sand, base resistance = 14 - 17 MPa.
Deformation of soil element around a pile
Images converted to displacement measurements using Particle Image Velocimetry (PIV) and close-range photogrammetry.
Measured strain paths
-12 -10 -8 -6 -4 -2 0 2 4-30
-20
-10
0
10
20
30
40
50
Soil element position relative to pile tip, h/B
εΙ
εΙII
εhεv
εΙεΙII ε
γ/2
Plane of projection
εv
εh
Compression
Extension
-8
-6
-4
-2
0
2
4
6
8
10
-12 -10 -8 -6 -4 -2 0 2 4Soil element position relative to pile tip, h/B
εΙεΙII ε
γ/2 Plane of projectionεv
εh
εΙ
εΙII
εh
εv
Compression
Extension
h
B
offset
Near the pile (offset = 1.5B) Far from the pile (offset = 3.5B)
Tests on silica sand and carbonate sand showed similar behaviour, but carbonate sand produced large strains and lower stresses.
Triaxial tests• The stress path was determined based on the pile driving mechanism. Creep was performed at various stages of the stress path.
•Note that an approximation was made to convert the 3D stress conditions to triaxial condition.
•A variety of granular materials (two silica sands, glass balls, glass shards) were tested to examine the effect of shape and particle strength.
0 200 400 600 800-200
0
200
400
600
800
1000Triaxial Stress Path
Mean Effective Stress, p (kPa)
Extension creep stage(48 hours to 3 weeks)
CSL
Soil element with local strain devices
Triaxial test data
Time (s)
100 101 102 103 104 105
101 102 103 104 105
0.00
-0.05
0.05
-0.10
-0.15
-0.20
-0.25
-0.30
0.00
0.05
0.10
0.15
0.20
0.25
Dev
iato
ric S
train
(%)
Vol
umet
ric S
train
(%)
Glass Ball
Leighton Buzzard Uniform Silica Sand
Glass Ball
Dilation
Montpellier Natural Sand
Leighton Buzzard Uniform Silica Sand
Montpellier Natural Sand
Stress State at Creep : p' = 600 kPa and q = 800 kPaAll Samples Were Prepared With Relative Density of Approximately 70%.
Pile-set-up due to dilatant creep1. Triaxial creep test (stress constant)
εv
time
contraction
dilation
σr’
time
relaxation stage
set-up by mean pressure increase
σr’
2. Soil around a pile (kinematic restraint)σr’
Fibre optic strain sensing in piles
• Installed at BRE test site, Chattenden
• Monitor minipiles in group during load tests
• Attached to rebar• Optical fibre
pretensioned• Comparison with and
complementary to vibrating wire strain gauges
Depth 7m,Minipiles143mm dia,Central pile300mm dia,1.2m cube pile cap
Strain sensor technology comparison
DistributedDiscreteDiscreteMeasurement
Distributed measurementHigh strain accuracyEstablished techniqueFeatures
Analyser £50kFibre ~£.0.1-10/m
Analyser £20kGratings ~£50-300 each
Analyser ~£1-10kSensor £80-250
Cost
~10,000µε~10,000µε3,000µεMaximum strain
Brillouin gain spectrum frequency shift
Bragg reflection frequency shift
Change of resonance in wireDetected physical quantity
4-25 minutesReal timeReal timeMeasurement time
1 measurement every 20cm
Range 10km (max 20,000)
Typically 40 sensors1 per copper cableNo. of measurements
1m ~2-20mm (length of grating)
50-250mmLimit of spatial resolution
30µε0.1-10µε0.5-1µεStrain resolution
Optical fibreFibre Bragg gratingVibrating wireSensor
BOTDR (eg. Ando AQ8603)
FBG (eg. Ando FB200)Vibrating wire
Brillouin optical time domain reflectometry (BOTDR)
Distributed strain sensor – BOTDRAverage strain over 1m every 20cmRange ~5-10kmResolution 30µε (0.003%)Low cost sensors - optical fibre5 - 25 minutes per measurementCan link or switch between fibres
Diagram courtesy of ntt.co.jp/news
Monitoring strain during load tests
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.85 0.87 0.89 0.91 0.93 0.95 0.97 0.990
0.25
0.5
0.75
1
1.25
1.5
Change
0t
90t
0
0.2
0.4
0.6
0 0.5 1
Distance / km
Distance / kmStra
in /
%
What can it be used?• Research
– Load tests – construction of load transfer functions– Clearer understanding of pile group behavior
• Monitoring lifespan of the structure (part of smart structures approach)– Post-earthquake diagnostic of a structure– Behavior due to long-term changes, (consolidation, capacity
increase with time etc.) • Adaptive Design
– Tunnel excavation below an existing structure.– Changes in building designation. – Additional floors/adding removing walls.
• Reuse of old piles– Increased pile capacity due to kinematic hardening
Piles are subjected to additionaloads due to bridging effect
l
P
z
t
t(z)
z
t
z
t
z
t
z
t
z
t
P=0
First Loading Unloading
z
t
z
t
z
t
P
Reloading
Bankside123 Installation
• Long term bearing pile monitoring– φ1.6m, 50m deep piles,
Strain sensors: BOTDR, vibrating wire, FBG
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 ThamesLinktunnel
Canal basin
New tunnel
King’s CrossSt Pancras Reproduced from Ordnance Survey of Northern Ireland mapping with the
permission of the Director and Chief Executive, © Crown Copyright.
3.6m
6.5m
8.5m
Innovation in Monitoring of Aging Infrastructure
• Fiber optics• Micro Electro Mechanical Sensors (MEMS)• Wireless Network Systems
MEMS
Connection Tab for Bottom Electrode
Connection Tab for Microbridge(Upper Electrode)
50 62.5 125 62.5 50
15 15
Bottom Driving Electrode
Microbeam
2550
253 1
60560
1532
.55
5
22.5 5 22.5
12.5
15
Substrate
Schematic drawing of a mircobeam (all units in micrometer)
Note:1. Electrostatic excitation and capacitive detection tecnhique is adopted.2. Microbeam thickness is 1 micrometer.3. Gap between microbeam and bottom electorde is at least 1.5 micrometer.
Micro-machined Reflectors
Warnecke et al., 2001From David Moore (CUED)
Lucent Technologies Lucent Technologies
Modelling (Better understanding of long-term soil behaviour
Monitoring (optimum numberof measurements)
Important soil properties?• Permeability• Undrained-partially
drained-drained behavior
• Stiffness anisotropy
Boundary conditions• Interface permeability
Key Performance Indicators?
• Ground or structure movements
• Crack developments
Future of Geotechnical Engineers?
• Need to perform life cycle assessment and embodied energy evaluation of geotechnical structures/construction
• Requires risk assessment (social, environmental, economic)
• Long-term prediction and monitoring• How can we incorporate this into design? • Do we have enough technical knowledge on
predicting (uncertain) long-term future events?