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Dynamic Cone Penetrometer Testing on Dynamic Cone Penetrometer Testing on Airport Subgrade SoilsAirport Subgrade Soils
Researcher: Michael WattsREU Sponsor: Dr. Mike Mooney
What is a Dynamic Cone What is a Dynamic Cone Penetrometer (DCP)?Penetrometer (DCP)?
8 kg. hammer drops 575 mm
Hammer hits an anvilsending the cone-tipped rod into the soil
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
Dynamic Penetration Index Dynamic Penetration Index (DPI)(DPI)
Uses of the DCPUses of the DCP
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 ResearchPurpose 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 MethodsTest 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 core-drilling at test sites
0
6
12
18
24
30
36
42
48
16 34100-15
0
6
12
18
24
30
36
42
48
w (%)asphalt concrete
gravel
(GW GM)
gravelly lean clay
(CL)
(CL)
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
w (%)
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
1000-30
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
in corehole
offset
2000-37.5
asphalt
(SC)
(SC)
(CH)
lean clay (CL)
lean clay w/ sand (CL)
clayey sand (SC)
w (%)
3000-45
0
6
12
18
24
30
36
42
48
asphalt
0
6
12
18
24
30
36
42
48
w (%)
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
in coreholeoffset
DPI (in./blow)0 2 4 6 8
Dep
th (
in.)
0
6
12
18
24
30
36
42
48
in corehole
offset
Seminole
4000-60 4900-73
asphalt
well graded gravel w/ sand(GW)
-same-
silt w/ gravel(ML)
sandy lean clay(CL)
0
6
12
18
24
30
36
42
48
asphalt
(GW GM)
-same-
(SC)
w (%)0
6
12
18
24
30
36
42
48
w (%)
asphalt
GW GM
-same-
(well-graded)
GM
SC
SM
same
18.21
9.1810.87
15.04
17.37
6.03
7.13
14.8913.63
13.32
17.4312.3223.0724.26
23.70
11.15
12.35
11.87
1.05
3.41
22.12
20.42
Figure 6
Results of DCP TestingResults of DCP Testing
SOIL TYPE
(USCS)
RANGE of W% RANGE OF DPI FOR
LAYER OF SOIL TYPE
(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.
3517
DPI (in./blow)0 2 4 6 8
De
pth
(in
.)
0
6
12
18
24
30
36
42
48
Shawnee
100-2
4000-60 5500-98
DPI (in./blow)0 2 4 6 8
De
pth
(in
.)
0
6
12
18
24
30
36
42
48
DPI (in./blow)0 2 4 6 8
De
pth
(in
.)
0
6
12
18
24
30
36
42
48Mr (ksi)
0 5 10 15 20
De
pth
(in
.)
0
6
12
18
24
30
36
42
48
Mr from DPI
Mr from SASW
Mr (ksi)0 5 10 15 20
De
pth
(in
.)
0
6
12
18
24
30
36
42
48
Mr from DPIMr from SASW
Fig
ure
8
If only REU lasted until If only REU lasted until December. . .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
