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Predicting Future Performance of Improved Soils from Today’s Test
Data
David A. Saftner, Russell A. Green, & Roman D. Hryciw
Ø Sand Aging Overview
Ø Field Testing
Ø Explosive Compaction
Ø NEES Vibroseis Testing
Ø Laboratory Testing
Ø Summary
Outline
Sand Aging OverviewPractical Application
+4
+2
0
-2
-4
-6
-8
-10
-12
-14
10 15 2050Le
vel:
mPD
CPT qc (MPa)
Post-vibrocompaction(~2 weeks after)
Pre-vibrocompaction
Post-vibrocompaction(~6 weeks after)
Minimum Allowable qc
(from Debats and Sims 1997)
Proposed Mechanisms: Ø Mechanical – micro-level particle
rearrangement
Ø Chemical – precipitation and cementation
Ø Dissolution of bubbles – blast gas or air
Ø Biological – microorganisms
Sand Aging Overview
Methods of dealing with aging: Ø Scheduling time to allow aging to
occur
Ø Site specific aging metrics based on test improvement projects
Ø Several proposed relationships:
Sand Aging Overview
Methods of dealing with aging: Ø Schmertmann et al. (1986)
Ø Based on observations of a dynamic compaction test site prior to main site improvement project
Sand Aging Overview
Time between improvement and CPT (days)
Factor by which to multiply qc
5 1.35
10 1.2
15 1.15
20 1.12
30 1.06
40 1.03
50 1.01
60 1.00
Methods of dealing with aging: Ø Mesri et al. (1990)
Sand Aging Overview
cD CCC
RRc
c
t
t
q
q/
)(
α
=
(qc)R = tip resistance at a reference time after the end of primary consolidationt = time of aged tip resistance measurementtR = reference time following primary consolidationCD = parameter reflecting densification methodC = secondary compression indexCc = compression index
Methods of dealing with aging: Ø Charlie et al. (1992)
Sand Aging Overview
)log(*1)(
)(
_1
_ NKq
q
weekc
weeksNc +=
K = empirical constant based on the chartN = number of weeks since disturbance
Methods of dealing with aging: Ø Joshi et al. (1995)
Sand Aging Overview
bt taP
P)(
1
=a b
Dry state 0.9 0.06
Distilled water 0.75 0.15
Sea water 0.7 0.17
Pt, P1 = penetration resistance on tth and 1st day following disturbance, respectivelyt = aging period in daysa, b = constants depending on environmental conditions with average values shown in the table above
Field Testing
Blast site
Vibroseis site
Paleo-liquefaction features
Field TestingPaleo-liquefaction feature
Field Testing
Clay
Loose ~GWTSand
DenseSand
LooseGravellySand
1.5m
3m
5m
10m
14m
Lower Liquefiable Layer
Upper Liquefiable Layer
Field TestingCone Penetration Test
Friction SleevePressure
Transducer
Vision Cone Camera
Accelerometer
Explosive Compaction
Explosive Compaction
20’
CPT
Pre-Blast
One Week
One Month
2.5 Months
3.5 Months
CPTu
SCPT
DMT
VisCPT
One Year
A
A’
1.15m (45.9”)
Explosive Compaction
Clay
Loose ~GWTSand
DenseSand
LooseGravellySand
1.5m
3m
5m
10m
14m
6.1m (20’)
0.1m (4.5”)
0.6m (22.5”)
12m
View A-A’
Explosive Compaction
Explosive Compaction0 5 1
015
20
25
30
35
400
20
Tip resistance, q
c (MPa)
Pre-Blast Range (7 tests)One Week Range (6 tests)2.5 Month Range (3 tests)
Upper Liquefiable Layer
Lower Liquefiable Layer
2
4
6
8
10
12
14
16
18
Dep
th,
z (m
)
Explosive Compaction
Dep
th, z
(m
)
One Week Range (6 tests)2.5 Month Range (3 tests)
0 2 4 6 8 10
12
141
.5
2
2.5
3
3.5
4
4.5
5
Tip resistance, q
c (MPa)
One Week Range (6 tests)2.5 Month Range (3 tests)
Explosive Compaction0 2 4 6 8 1
01.5
2
2.5
3
3.5
4
4.5
5
Tip resistance, q
c (MPa)
One Week Average (6 tests)1 Month Average (3 tests)2.5 Month Average (3 tests)1 Year Average (3 tests)
Dep
th,
z (m
)
Explosive Compaction100 110 120 130 140 150 160 170 180 190 2002
3
4
5
6
7
8
9
10
11
Shear Wave Velocity, Vs (m/s)
Depth, z (m)
NEES Vibroseis
NEES Vibroseis
CPT
Pre-Blast
One Week
One Month
9 Months
SCPT
DMT
VisCPT
7.5’
NEES Vibroseis
NEES Vibroseis
Upper Liquefiable Layer
Dep
th,
z (m
)
0 5 10
15
20
25
30
35
400
1
2
3
4
5
6
7
8
9
10
Tip resistance, q
c (MPa)
Post-shake range (3 tests)One month range (3 tests)
Upper Liquefiable Layer
Dep
th,
z (m
)
NEES Vibroseis0 5 1
015
20
25
30
35
400
1
2
3
4
5
6
7
8
9
10
Tip resistance, q
c (MPa)
Pre-shake average (4 tests)Post-shake average (3 tests)One month average (3 tests)One year average (3 tests)
Upper Liquefiable Layer
Dep
th,
z (m
)
Laboratory Testing
0.010.11100
10
20
30
40
50
60
70
80
90
100
Grain Size Distribution in Upper and Lower Liquefiable Layers
Diameter (mm)
% Passing
Laboratory Testing
Ø Sand aging is important because of dependence on in-situ testing when developing QA metrics
Ø Following explosive compaction, CPT qc and Vs showed time-dependent increases
Ø Following vibroseis shaking, Vs showed slight time-dependent increases but little change to CPT qc
Summary
Ø Comparison of several field disturbance techniques and laboratory testing performed on the same site/soil is unique in aging literature
Ø Synergistic laboratory/field components of this research will allow development of a metric that predicts future in-situ test results using today’s data
Summary
Ø EERI, FEMA, & NEHRPØ NSF & NEESØ Professors Jerry Lynch, Richard
Woods & Kyle RollinsØ Jan Pantolin & Yongsub JungØ Mulzer Crushed Stone, IncØ Spartan Specialties, Ltd
Acknowledgements