Dynamic Cone Penetration Test (DCPT)
In geotechnical engineering and foundation engineering standard penetration tests (SPT)1 and cone penetration (CPT)2 in situ (In-Site) widely used to check the soil conditions of project on site location in order to analyze it and used the structural design. SPT test can be done by a dynamic mechanism with a guided sampler and help of hammer blows, while in CPT test penetration test cone-guided by a semi-static mechanism. In a dynamic cone penetration testing DCPT3 guided with a penetrometer cone by a dynamic mechanism and Indicative the property of both methods.
DCPT tests done by two persons and launched a quick test, for the run and check the results at the project site. This obtained Due to the economic and simplicity as well as a better understanding of the results, it can help to reduce the costs and to efforts to investigate the soil.
In Iran to conduct the DCPT test in is used 10-kilogram hammer it so-called "10-kilogram German handy hammer" will be compared with SPT Tables and following formula results.
Standard: |
DIN 4094 |
Name of
Apparatus
|
Shafts
Diameter
d
(mm)
| Head Diameter do
(mm) |
Head Angel
degree
|
Hammer
Weight
w
(kg) |
Falling
Height
h
(cm)
|
Head Area
A
(cm2)
|
Depth of
Penetration
in Soil
D
(cm)
|
Energy consumption
per unit area of the head
E
(kg/cm)
|
Total Energy
or Work
E'
(kg/cm2)
|
Hit ratio in comparison
with American SPT
|
---|---|---|---|---|---|---|---|---|---|---|
Light German SPT
|
22
|
35.6
|
90
|
10
|
50
|
10
|
20
|
50
|
2.5 n
|
3.20
|
Heavy German SPT
|
32
|
43.7
|
90
|
50
|
50
|
15
|
20
|
167
|
8.4 n
|
0.95
|
American SPT
|
36
|
50.8
|
-
|
63.5
|
76.2
|
20.2
|
30
|
240
|
8.0 n
|
1.0
|
- Formulas for calculating the energy used in the experiment:
1. E = (w×h)⁄A kg/cm 2. E' = ((w×h)⁄A)×(n/D) kg/cm2
n : Number of blows
- Formula converting SPT German style to SPT American:
N30 = N20 / 3.2
Light German SPT All joints are screwed.
|
SMSO-8100
|
1. SPT = Standard Penetration Test2. CPT = Cone Penetration Test3. DCPT = Dynamic Cone Penetration Test