Predicting Future Performance of Improved Soils from Today ... fileClick to edit Master subtitle...

Click to edit Master subtitle style

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