Miniature Pressuremeter and
Miniature Cone Penetrometer Testing
in Calibration Chamber with
Unsaturated Soil Beds
By
Norman K. Tan
Outline
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•
•
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•
•
Introduction
Objective
Research task
Why calibration chamber?
OU calibration chamber
Preparation of soil beds
Test results
Research question.
Introduction
• Cone Penetrometer (CPT) & Pressuremeter (PMT)
– Popular in situ testing devices
– Give estimates of in situ soil properties
– Methods developed to interpret results focus around:
• Saturated soil
• Dry sand
• About 1/3 of earth ~ arid/semi arid regions
• Behavior of unsaturated soil is different from saturated
soil
• Motivation: No methods for interpreting CPT & PMT in
unsaturated soil
Objective
• Develop a method to predict PMT and CPT
responses for various matric suction based
on one test result
Research Task
• Calibration chamber testing
• Numerical and analytical analysis and
modeling
• Laboratory testing
Research task
Calibration
Chamber Testing
Modeling
Laboratory Testing
~Soil properties
Why Calibration Chamber?
• Field Testing
–
–
–
–
Easy and cheaper
Lack of control over the boundary conditions
Heterogeneous of soil
Unknown stress history, stress state, etc.
• Calibration Chamber Testing
– Controlled environment
•
•
•
•
Boundary condition
Stress state
Homogeneous soil beds
Etc.
OU Calibration Chamber (OUCC)
• Allows independent control
of radial & axial stress (BC1)
• Designed working pressure ~
1380 kPa
• Capable to perform axis
translation
• Pore air & pore water can be
controlled independently
• Burettes system: measure
water volume change
• DAVI: measure diffused air
volume
• LVDTs ~ measure total
volume change
• Soil beds
– diameter: 610 mm
– Height: 450 mm to
1350 mm
Soil Bed
Preparation of Soil Beds
• Soil used:
–
–
–
–
Minco Silt
From Tuttle, OK
CL-ML soil
PI: 8
• Soil bed preparation:
– Statically compacted
– 152 mm/layer
• Soil preparation:
– Oven dried
– Pass #10 sieve
– Mixed with water in large
concrete mixer
– Store in 5 gallon pails for
minimum of 1 day
• Soil bed consolidation
– 35 kPa increment
– Up to 103 kPa
OU Miniature Pressuremeter (MPMT)
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•
•
•
•
Diameter: 15.2 mm
Length: 130 mm
H/D: 8.5
Dsoilbed/Dprobe: 40
Test Depth:
– 267 mm (center of probe)
– 495 mm (center of probe)
OU Miniature Cone Penetrometer
(MCPT)
• Diameter: 8.9 mm
• Dsoilbed/Dprobe: 68.5
• Penetration rate: 0.5 cm/sec
Typical MPMT Results
120
100
Corrected Pressure (psi)
• Limit Pressure
~ defined as pressure
at which vol. of the
cavity is twice of
initial soil cavity
volume
~ determined using
1/v vs P plot
80
60
40
20
0
-20
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Corrected Volume (in3)
160
150
•From test: CCT6 PMT 6-2
Summary of MPMT Results
Test ID:
PMT2-1
PMT2-2
PMT3-1
PMT3-2
PMT4-1
PMT4-2
PMT5-1
PMT5-2
PMT6-1
PMT6-2
PMT8-1
PMT8-2
PMT9-1
PMT9-2
PMT10-1
PMT10-2
PMT11-1C
PMT11-2C
PMT11-1S
PMT11-2S
PMT11-1E
PMT11-2E
PMT11-1W
PMT11-2W
Ep
(kpa)
14836
14154
21113
31434
7943
7868
13101
17415
26023
20629
9875
8811
15237
12050
15166
18578
11224
14208
11836
13547
8668
13448
12411
10338
Er
(kpa)
23396
23879
22608
31606
12329
12752
25098
28955
57144
60287
15789
18972
20572
22611
35707
37243
29656
39401
25794
26092
18579
22372
19567
18234
PL
(kpa)
839
766
1341
1585
641
605
771
787
1026
977
525
545
766
734
835
770
490
525
488
524
488
580
528
507
w
(%)
10.1
11.0
5.9
5.4
12.5
12.8
7.8
8.1
8.7
8.6
7.3
7.2
8.8
8.7
8.0
8.2
6.1
5.9
6.0
6.0
6.1
5.9
6.2
5.9

(%)
14.1
15.4
7.8
7.4
18.0
18.7
10.7
11.2
12.3
12.5
9.5
9.4
12.1
12.1
11.1
11.3
8.0
7.7
8.0
7.9
7.8
7.6
8.1
7.6
d
(kN/m3)
13.7
13.7
13.0
13.3
14.2
14.3
13.5
13.5
13.9
14.3
12.8
12.8
13.5
13.5
13.5
13.5
12.9
12.8
13.1
12.9
12.7
12.7
12.8
12.6
 interpreted
(kPa)
23.8
19.6
59.7
60.1
13.2
12.0
41.5
38.6
32.0
31.1
49.7
50.3
33.2
33.3
39.1
37.6
58.8
59.7
58.8
59.2
59.4
59.9
58.4
60.0
MPMT Results
1800
Limit Pressure (kPa)
1600
1400
1200
1000
800
600
400
200
0
0.0
10.0
20.0
30.0
40.0
50.0
Interpreted Matric Suction (kPa)
60.0
70.0
MPMT Results
1800
Limit Pressure (kPa)
1600
1400
1200
1000
800
600
400
200
0
12.4
12.6
12.8
13.0
13.2
13.4
13.6
13.8
Dry Unit Weight (kN/m^3)
14.0
14.2
14.4
14.6
Dry Unit Weight (kN/m^3)
MPMT Results
14.6
14.4
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
12.6
12.4
0.0
10.0
20.0
30.0
40.0
50.0
Interpreted Matric Suction (kPa)
60.0
70.0
MPMT Results
35000
30000
Ep (kPa)
25000
20000
15000
10000
5000
0
0.0
10.0
20.0
30.0
40.0
50.0
Interpreted Matric Suction (kPa)
60.0
70.0
MPMT Results
35000
30000
Ep (kPa)
25000
20000
15000
10000
5000
0
12.4
12.6
12.8
13.0
13.2
13.4
13.6
13.8
Dry Unit Weight (kN/m^3)
14.0
14.2
14.4
14.6
• w: 6%
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
8000
7000
6000
5000
4000
CPT 1 C
3000
2000
1000
0
7000
6000
5000
4000
CPT 1 B
3000
2000
1000
0
7000
6000
5000
4000
3000
2000
1000
0
7000
6000
5000
4000
3000
2000
1000
0
Depth (cm)
CPT 1 A
MCPT Results
CPT 1 D
0
20
40
60
80
100
120
140
• w: 8%
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
8000
7000
6000
5000
4000
CPT 2 C
3000
2000
1000
0
7000
6000
5000
4000
CPT 2 B
3000
2000
1000
0
7000
6000
5000
4000
CPT 2 A
3000
2000
1000
0
7000
6000
5000
4000
3000
2000
1000
0
Depth (cm)
MCPT Results
CPT 2 D
0
20
40
60
80
100
120
140
• w: 10%
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
qc (kN/m2)
8000
7000
6000
5000
4000
CPT 3 C
3000
2000
1000
0
7000
6000
5000
4000
CPT 3 B
3000
2000
1000
0
7000
6000
5000
4000
CPT 3 A
3000
2000
1000
0
7000
6000
5000
4000
3000
2000
1000
0
Depth (cm)
MCPT Results
CPT 3 D
0
20
40
60
80
100
120
140
MCPT Results
0
20
Depth (cm)
40
60
80
100
120
qc (kN/m2)
• CPT 1 A ~ w: 8%
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
14
13
12
11
10
0
1000
2000
3000
4000
5000
6000
7000
140
Dry Unit Weight (kN/m3) Gravimetric Water Content (%)
Relative Frequency (%)
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Relative Frequency (%)
Relative Frequency (%)
MCPT Results: qc Histogram
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0
CPT1A
CPT1B
CPT1C
CPT1D
CPT2A
CPT2B
CPT2C
CPT2D
CPT3A
CPT3B
CPT3C
CPT3D
1000 2000 3000 4000 5000 6000 7000
qc (kPa)
0
1000 2000 3000 4000 5000 6000 7000
qc (kPa)
0
1000 2000 3000 4000 5000 6000 7000
qc (kPa)
0
1000 2000 3000 4000 5000 6000 7000 8000
qc (kPa)
MCPT Results: m0 of qc
MCPT Results: m0 of qc
4500
4000
m o qc (kPa)
3500
3000
2500
2000
1500
1000
500
0
0
10
20
30
40
50
Average Interpreted Matric Suction (kPa)
60
70
MCPT Results
0
10
20
30
40
Depth (cm)
50
60
70
80
90
100
110
120
130
CCT3B
140
0
1000
2000
3000
4000
qc (kPa)
5000
6000
7000
8000
MCPT Results
TEST ID
CPT1A
CPT1B
CPT1C
CPT1D
CPT2A
CPT2B
CPT2C
CPT2D
CPT3A
CPT3B
CPT3C
CPT3D
INTERPRETED
MATRIC
SUCTION (kPa)
59
59
59
59
43
43
44
45
27
22
23
27
HISTOGRAM
(MEAN)
3888
4055
4006
3918
2883
3208
2978
3101
2979
2779
2908
3035
qc (kPa)
MIN-MAX
MEAN
4073
4133
4062
4056
3224
3622
3347
3170
3362
3314
3047
3340
OVERALL
MEDIAN
3739
3961
4012
3814
2761
3208
2971
3029
3157
2883
2858
2970
MCPT Results
4500
qc(kPa)
4000
3500
3000
2500
2000
0
10
20
30
40
50
60
Interpreted Matric Suction (kPa)
HISTOGRAM (MEAN)
MIN-MAX MEAN
OVERALL MEDIAN
70
Research Questions ???
• What is the true value of H, v for Minco Silt?
• Does c`, `, b varies with initial water
content, dry unit weight? How significant?
• Are the interpreted matric suctions the true
matric suctions?
• Explanations for the PMT response:
~ trend in ua-uw vs. Pl plot
Thank you !!!