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Williamson Drive Probe

Correlation Data

WDP

Clear surface of duff and organic material to expose the upper surface of the soil.
Number of blows required to advance the hole 6 inches is recorded.
Said in Volume II pg 422 “The WDP is best suited for silts and sands without gravel or rock fragments.”

SPT

63.5 kg hammer
dropped .76 m
pre bored hole diameter 60-200mm
SPT driven 15cm after pre bored hole
After that it is driven 30cm with number of blows recorded.
Common efficiency is 60% for energy transfer to head of drill rod
Pre bored hole is to be 5mm larger than sampling hole.
Pre bored hole is to be less that 170 mm in diameter
Spoon size: OD=2in ID=1.375in, L=27in Sample L=21in
Operated between 40-60 blows per minute

http://web.umr.edu/~rogersda/umrcourses/ge441/NOTES%20for%20STANDARD%20PENETRATION%20TEST.pdf

Drill hole varying in diameter from 60-200mm
Hammer down 15cm
Then hammer down 30 cm keeping track of required blows for this amount.
Operate between 40-60 blows/minute
140lb hammer falling 30 inches

Moisture content of the soil is vital to proper compaction

http://www.concrete-catalog.com/soil_compaction.html

Soil Density or Consistency
Density (Granular)	Consistency (Cohesive)	THD Penetrometer (blows/ft or blows/300mm)	Field Identification
Very Loose	Very Soft	0 to 8	Core (height twice diameter) sags under own weight
Loose	Soft	8 to 20	Core can be pinched or imprinted easily with finger
Slightly Compact	Stiff	20 to 40	Core can be imprinted with considerable pressure
Compact	Very Stiff	40 to 80	Core can only be imprinted slightly with fingers
Dense	Hard	80 to 5 " /100 (125mm/100)	Core cannot be imprinted with fingers but can be penetrated with pencil
Very Dense	Very Hard	5 " /100 to 0 " /100 (125mm/100 to 0mm/100)	Core cannot be penetrated with pencil