Post on 06-Apr-2018
The Dynamic Cone Penetrometer
“The DCP”
Gavin P. Gautreau, P.E.
Geotechnical Research Manager
Louisiana Transportation Research Center (LTRC)
• Purpose & Concept
• Parts
• Operation/Technique
• Data Recording
• Calculations/Analysis
• Advantages/Disadvantages
• Implementation
Presentation Objectives:
• Purpose & Concept
– Dynamic Cone Penetrometer
– Shallow Pavement Applications
– Measures Stiffness, mm/blow
– Simple Concept
• Stiff material requires more drops
• Weak material requires fewer drops
– Non Nuclear
– Design Information
– Quick and Cost Effective
– Another “Tool for the Toolbox”
• Parts– Handle
– Upper Rod (5/8” dia)
– Hammer
• 17.8 pounds (8kg)
• 22.6 inch drop
– Anvil & Lower Rod
– Cone Tip (60 degree, ¾” dia)
– Measuring Stick with cm & mm divs.
– Other
• Hammer Drill
• Generator
• Farm Jack
• Operation (Preparation)
– Hammer Drill
• Quickly thru Asphalt or
Concrete
• Minimal Intrusion
• Various Length bits
• Dry vs wet coring rig
– Crew
• Operator
• Reader
• Recorder
(A)(B)
• Operation cont’d
– Record reference reading (A)
• Measuring stick is stationary
– Lift hammer to handle
– Release hammer
– Record reading after hammer
drop (B)
– Repeat drop, read and record
each drop thru pavement
layers(?)
(A)(B)
• Technique
– Keep straight (vertical)
– Avoid banging hammer
into handle during lift.• Can lose disposable cone
• Damage to device
– Spin rod after each drop.
– Keep ruler stationary
– Record reading after
every hammer drop.
(X)
(Y)
• Data Recording (Currently developing TR method)
– Project Information
• Site Location
• Station #
• Distance from Centerline
• Elevation (if available)
– Pavement Information (as available)
• Cross-Section Thickness Information
• Material Types (classification and gradation)
• Compaction Info (Proctor Moisture and Density) as
available
• Nuclear Gauge Information if available
(A) 46.0(B) 46.3
2 46.6
3 46.9
4 47.2
5 47.5
? ???
Top of Asphalt/Concrete
Top of Testing Surface
(bottom of drilled hole, if applicable)
Reading after First Blow
Reading after Second Blow
Anytown, LA – Hwy 1, Sta. 19+00 RL
Blow
#
Rod
Reading
0 NA
0 46.0(A)
Reading after Fourth Blow
Reading after Third Blow
Reading after Last Blow
Reading after Fifth Blow
• Data Recording, example
1 46.3(B)
,cm
example: stone base
Field Data
• Data Calculations (without drilling)
Blow
#
Rod
Reading, cm
0 NA
0 46.0
1 46.3
2 46.6
3 46.9
4 47.2
5 47.5
6 47.8
Distance
per Blow
Cumulative
Penetration
Distance below Surface
cm
this times
ten = DCPI
cm
Running Total
cm
can plot as inches or elev.
0.0 0.0equal to tip location
below surface
0.3 0.3 0.3
0.3 0.6 0.6
0.3 0.9 0.9
0.3 1.2 1.2
0.3 1.5 1.5
0.3 1.8 1.8
Field Data
• Data Calculations (drilling occurred)
Blow
#
Rod
Reading, cm
0 38.4
0 46.0
1 46.3
2 46.6
3 46.9
4 47.2
5 47.5
6 47.8
Distance
per Blow
Cumulative
Penetration
Distance below Surface
cm cm
Running Total
cm
can plot as inches or elev.
7.6Drilled depth
0.0tip location
below pavement surface
0.3 0.3 7.9
0.3 0.6 8.2
0.3 0.9 8.5
0.3 1.2 8.8
0.3 1.5 9.1
0.3 1.8 9.4
• Data Analysis
– Plotting Data
– Layer Changes
– Avg. mm/blow
Example, cont’d
0
5
10
15
20
25
30
35
40
0 20 40 60 80
Number of Blows
Cum
ula
tive P
enetr
ation,
cm
Anytown, LA – Hwy 1, Sta. 19+00 RL
3 mm/blowLayer Change
Layer Change
36 mm/blow
11.2 mm/blow
Number of Blows
De
pth
of P
en
etr
atio
n, cm
150+50 Rt Ln
2 mm/blow
4 mm/blow
6 mm/blow
8 mm/blow
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200Number of Blows
Cu
mu
lative
pe
ne
tra
tio
n,c
m
161+50 Lt Ln
2 mm/blow
4 mm/blow
6 mm/blow
8 mm/blow
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200
Number of Blow s
Cum
ula
tive p
enetr
atio
n,c
m
190+00 Lt Ln
2 mm/blow
4 mm/blow
6 mm/blow
8 mm/blow
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200
Number of Blow s
Cum
ula
tive p
enetr
atio
n,c
m
176+00 Lt Ln
2 mm/blow
4 mm/blow
6 mm/blow
8 mm/blow
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200Number of Blows
Cu
mu
lative
pe
ne
tra
tio
n,c
m
Recent Analysis
Example
1.310.9
56.3
0.72.2
20.3
0.62.9
18.3
1.85.5
37.2
Resilient Modulus Equations
• DCP - Direct Model
• DCP-Soil Property Model
d
rDCPI
M 42.01
0.221
32.1
DCPIM r
14.122
For Cohesive Soils: 1<Mr<14 ksi
Equations from LTRC Project 03-3P
R2 = 0.82
R2 = 0.89
DCPI
DCP Tests
ALF Lane 4
Base, Treated Subase, & Subgrade
Field & Laboratory Test Summary
Cross-Section
• Asphalt Surface (2”)
• Base (8.5”)– Stone
– BCS with 10% Slag
– BCS with FlyAsh (small untreated area at end)
– Foamed Asphalt
• Treated Subbase (12”)– Lime
– Cement
• Untreated Subgrade Co
ns
tru
cti
on
SUBGRADE DCP VALUES
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
20-Nov 10-Dec 30-Dec 19-Jan 8-Feb
TIME, DATE
AV
ER
AG
E M
M /
BL
OW
1A AVERAGE
2A AVERAGE
2A 0+10
1B AVERAGE
2B AVERAGE
3A AVERAGE
3B AVERAGE
November
Average =
28.9
February
Average =
13.6
TREATED SUBBASE DCP VALUES
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
20-Nov 10-Dec 30-Dec 19-Jan 8-Feb
TIME, DATE
AV
ER
AG
E M
M /
BL
OW
1A AVERAGE
2A AVERAGE
2A 0+10
1B AVERAGE
2B AVERAGE
3A AVERAGE
3B AVERAGE
Lime
Initial
Average
= 31.8
Cement
Average
= 5.3
Cement
Initial
Average
= 20.3
Lime
Average
= 7.3
BASE DCP VALUES
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20-Nov 10-Dec 30-Dec 19-Jan 8-Feb
TIME, DATE
AV
ER
AG
E M
M /
BL
OW
1A AVERAGE
2A AVERAGE
2A 0+10
1B AVERAGE
2B AVERAGE
3A AVERAGE
3B AVERAGE
BASE DCP VALUES
BCS & Slag
BCS & Fly Ash
BCS (Raw)
Stone
Stone
Foamed Asphalt
Foamed Asphalt
Each point represents 3 tests
per section per date.
DCP Advantages:
• Determines Stiffness in mm/blow
• Layer Changes identified by Slope
Changes
• Minimal surface disturbance
• Not “Rocket Science” and not “Nuclear”
• Method of acceptance and verification
• Design and Strength information via
Correlations (CBR, Mr, etc.)
• Simple reliable, cost-effective tool for
shallow pavement applications
Depth
Blow Count0Layer
Layer
Layer
• Disadvantages:
• Not for use on large stone, shell, asphalt, or
concrete
• DCP can break under repetitive drops in
very stiff material or with improper removal
• Does not measure moisture content or
density (only measures stiffness)
• Develop a comprehensive implementation plan for
the DCP with procedures that DOTD can use in its
daily production
• Develop or modify current DOTD specifications to
accommodate such changes.
LTRC Project: 06-4GT
Objectives:
This is a comprehensive follow-up study after four
LTRC research projects on involving DCP
applications.
Implementation
• Develop a device that can collect soil moistures
and soil penetration resistance.
LTRC Transportation Innovation Research
Exploration (TIRE) Project: 07-2TIRE
Objective:
Combined Soil Moisture Meter and Dynamic Cone
Penetrometer (DCP)
Professor Martin Feldman, LSU
Implementation
Questions?
Thanks,
Drive Safely