Transcript Dynamic Cone Penetrometers and Airport Pavement Management

Dynamic Cone Penetrometer Testing on
Airport Subgrade Soils
Researcher: Michael Watts
REU Sponsor: Dr. Mike Mooney
What is a Dynamic Cone
Penetrometer (DCP)?
8 kg. hammer drops 575 mm
Hammer hits an anvil
sending the cone-tipped
rod into the soil
Dynamic Penetration Index
(DPI)
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

A ruler is used to measure the distance rod
sinks into the soil.
DCP measurements are recorded as a
Dynamic Penetration Index (DPI)
DPI = depth / # of blows for cone-tipped rod
to reach that depth
Uses of the DCP

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Quick test for characterizing subgrade soils
Correlations have been developed between
DPI and a soil strength value called the
California Bearing Ratio (CBR)
CBR values are used in pavement design
Recent efforts have focused on developing
correlations between DPI and Resilient
Modulus (Mr), rather than correlations for
empirical tests such as the CBR test
Purpose of Research


Test effectiveness of DCP as an airport
subgrade soil profiling tool
To compare Mr calculations based on DCP to
Mr calculations from a non-destructive test,
Spectral Analysis of Surface Waves (SASW)
Test Methods

Goldsby and
Seminole Airports
– Holes drilled in asphalt
using gas core-driller
– DCP tests were
performed either in the
core-hole or in a offset
hole
– Soil was removed for lab
tests using a hand auger

Shawnee Airport
– Same procedures as
Goldsby and Seminole,
except SASW tests were
performed prior to coredrilling at test sites
Results of DCP Testing
Seminole
16
100-15
w (%)
0
w (%)
0
asphalt concrete
same
6
1.05
12
gravel
(GW GM)
3.41
18
gravelly lean clay
(CL)
24
(CL)
(SC)
12
12
18
18
22.12 36
42
42
48
48
0
0
6
6
30
36
DPI (in./blow)
2 4 6 8
0
asphalt
asphalt
6
20.42 24
30
w (%)
0
(SC)
(CH)
24
lean clay (CL)
30
lean clay w/ sand
(CL)
36
clayey sand (SC)
17.43
12.32
23.07
24.26
12
24
23.70 30
36
17.37
42
0
11.15
12.35
-same-
silt w/ gravel
(ML)
18.21
sandy lean clay
(CL)
11.87
48
48
0
DPI (in./blow)
DPI (in./blow)
0 2 4 6 8
0
0
0
asphalt
6
(GW GM)
asphalt
well graded gravel
w/ sand
(GW)
2
4
6
8
4900-73
w (%)
w (%)
18
42
DPI (in./blow)
0 2 4 6 8
4000-60
3000-45
2000-37.5
1000-30
0
12
-same-
18
(SC)
6
15.04 18
30
36
36
42
42
48
48
DPI (in./blow)
0 2 4 6 8
0
12
12
12
12
12
18
18
18
18
18
18
24
14.89
13.63
13.32
24
30
30
30
30
30
30
36
36
36
36
36
36
42
42
42
42
42
48
48
48
48
48
in corehole
offset
in corehole
42
48
offset
Figure 6
in corehole
offset
SM
6.03
7.13
Depth (in.)
Depth (in.)
Depth (in.)
12
Depth (in.)
6
Depth (in.)
6
Depth (in.)
6
24
GM
SC
30
6
24
GW GM
-same(well-graded)
24
6
24
asphalt
24
6
24
w (%)
0
9.18
10.87 12
DPI (in./blow)
0 2 4 6 8
34
SOIL TYPE
RANGE OF DPI FOR
RANGE of W%
LAYER OF SOIL TYPE
(USCS)
(in./blow)
GW-GM
3.41 - 9.18
0.1 - 0.4
GW*
11.15
0.2
GM
13.06 - 14.89
0.1 - 0.5
GM-GC
7.79 - 9.97
0.5 - 0.9
SM
10.98 - 14.28
0.5 - 1.0
SC
12.32 - 17.43
1.0 - 1.5
ML
12.89 - 20.74
0.5 - 4.0
ML-CL
13.13 - 14.58
0.9
CL
11.87 - 24.26
0.6 - 3.8
CH*
23.07
2.5
* Only one layer of this soil type was encountered.
Shawnee
4000-60
5500-98
17
35
100-2
DPI (in./blow)
0
0
2
4
6
DPI (in./blow)
DPI (in./blow)
8
0
0
2
4
6
8
0
6
12
12
12
18
18
Depth (in.)
24
24
30
30
42
42
42
48
48
0
5
10
15
20
0
6
12
12
18
18
Mr (ksi)
10
15
20
Mr from DPI
Mr from SASW
Depth (in.)
24
24
30
30
36
36
Mr from DPI
Mr from SASW
42
48
Figure 8
48
5
Depth (in.)
6
42
0
8
30
36
0
6
24
36
Mr (ksi)
4
18
36
48
2
Depth (in.)
6
Depth (in.)
6
0
If only REU lasted until
December. . .

Further study could have focused on:
– Exploring further the relationship between DPI and
soil material/water content
– Comparing Mr calculations based on DPI to Mr
values derived from lab tests on the same soil
– Exploring the differences in Mr values based on
DCP testing from Mr values based on SASW
testing