Summary log for dynamic probing
|Place within which or which is nearest to*) location of penetration test:|
|x, y, z-coordinates:|
|Name and location of project:|
|Date of test:|
|Type of dynamic probing *): DPL, DPM, DPH, DPSH-A, DPSH-B:|
|Equipment checked and in accordance with EN ISO 22476-2, 5.1; Yes/No*) on:|
|Field sketch (scale 1 : /not to scale)*)
with direct geotechnical investigations (e.g. boreholes) entered:
|Other relevant data:|
|Name of the operator in charge:|
|*) Delete as applicable.|
Record of measured values and test results for dynamic probing
|Client/name of project:|
|x, y, z-coordinates|
|Depth; add 10, 20 or 30 m (as depth > 10 m): + m|
|*) delete as applicable.
**) measured torque
Groundwater: ....... m below starting point
Name and signature of the operator in charge:
Recommended method to measure the actual energy
The measurement of the energy transmitted to the drive rods can be made by means of an instrumented section of rod positioned at a distance greater than 10 times the rod diameter below the point of hammer impact on the anvil (see Figure C.1).
- 1 Anvil
- 2 Part of instrumented rod
- 3 Drive Rod
- 4 Strain gauge (measuring transducer)
- 5 Accelerometer
- 6 Ground F Force
- dr Diameter of the rod
The measuring device consists of a removable instrumented rod fixed between the anvil and the head of rods. It includes:
- system for measurement of vertical acceleration having a linear response up to 5 000 g;
- system for measurement giving the axial deformation induced in the rod;
- apparatus, with a resolution better than 1 × 10-5s, for viewing, recording and pre-treatment of the signals;
- data processing system (data logger and computer).
When strain gauges are used for the measurement of the axial deformation, they should be uniformly distributed around the instrumented rod, preferably in two orthogonal pairs.
At each impact, check the correct operation of the measuring equipment and the sensors by displaying the results of measurements.
It should be verified that the signals from the accelerometers and of the gauges are null before and after the impact.
For the measurement of the acceleration and deformation, the precision should be better than 2 % of the measured value.
C.4.1 The force F transmitted to the rods is calculated as follow:
- εm(t) is the measured axial deformations of the instrumented rod at time t;
- Aa is the cross-sectional area of the instrumented rod;
- Ea is the Young's modulus of the instrumented rod.
C.4.2 The particle velocity v(t) of the measurement section is calculated by integration of the acceleration a(t) with time t.
C.4.3 The basic equation for the energy E which passes into the drive rods is:
E(t') is the driving energy which passes into the drive rod up to time t' after the impact.
NOTE Various methods for developing the above equation and additional information can be found in the Bibliography. C.4.4 The hammer energy to take into account is the mean value obtained from at least five measures:
C.4.5 The hammer energy ratio which characterises each dynamic penetrometer is given by:
Etheor = m × g × h;
- h is the falling height of the hammer;
- m is the mass of the hammer;
- g is the acceleration due to gravity.
(Key see Figure C.1)
|Hammer Energy Measurement Report|
|Type of dynamic probing|
|Date of the test|
|Mass of the hammer m|
|Falling height h|
|Etheor = m × g × h|
|Characteristics of the instrumented rod|
|Length of the instrumented rod Ia|
Name and signature of the operator in charge
|Emeas =||Etheor =|