Dynamic Cone Penetrometer Testing on Airport Subgrade Soils

1
Dynamic Cone Penetrometer Testing on Airport
Subgrade Soils
Researcher Michael Watts REU Sponsor Dr. Mike
Mooney
2
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
3
Dynamic Penetration Index (DPI)

• 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

4
Uses 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

5
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)

6
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 core-drilling
  at test sites

7
(No Transcript)
8
(No Transcript)
9
Results of DCP Testing
10
(No Transcript)
11
(No Transcript)
12
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