Ramming sounding
The dynamic probing is a building digestion process in the building industry , is rammed in which a probe with a fixed energy into the ground. The number of blows required for a defined penetration depth is recorded. In the case of cohesive (non-cohesive) soils, conclusions can be drawn about the storage density from the number of blows .
An alternative is to carry out pressure soundings (CPT) or the standard penetration test or borehole drilling .
The ramming sounding should not be confused with the ramming core sounding , which is used to obtain soil samples.
Ramming soundings are regulated in DIN EN ISO 22476-2. DIN 4094-3 applied until 2005.
Probing devices
Depending on the existing soil and the required exposure depth, you can choose between several probing devices. The light probing devices (DPL, Dynamic Probing Light) used to include the light ramming probe DPL-5 with a tip cross-section of 5 cm² and the light ramming probe DPL with a tip cross-section of 10 cm², which remained in the new DIN EN ISO 22476-2 standard. The DPL-5 ramming probe , which no longer complies with the standard, was also referred to as the Künzelstab . Medium-weight probing devices (DPM, Dynamic Probing Medium) can also be selected. Heavy ramming probes DPH (Dynamic Probing Heavy) and super-heavy ramming probes DPSH-A and DPSH-B (Dynamic Probing Super Heavy, Variants A and B) or DPG (Dynamic Probing Giant) are also available. In addition to a different tip cross-section and tip diameter of the probing tip, the devices are equipped with different drop weights and drop heights.
The German abbreviations LRS (light ramming probe), SRS (heavy ramming probe) are also used, each with the tip cross-section in square centimeters as additional information.
| Surname | abbreviation | Tip cross-section in cm² |
Tip diameter in mm |
Mass of the ram in kg |
Fall height in m
|
|---|---|---|---|---|---|
| Light ram probe | DPL | 10 | 35.7 | 10 | 0.5 |
| Medium weight piling probe | DPM | 15th | 43.7 | 30th | 0.5 |
| Heavy ram probe | DPH | 15th | 43.7 | 50 | 0.5 |
| Super heavy ramming probe A | DPSH-A | 16 | 45.0 | 63.5 | 0.5 |
| Super heavy ramming probe B | DPSH-B | 20th | 50.5 | 63.5 | 0.75 |
| Standard penetration test | SPT | 20th | 50.5 | 63.5 | 0.76 |
Implementation and evaluation
The ram, with the help of which the probing rod is rammed into the ground, is brought to a predefined height either by means of air pressure or muscle power (DPL) or a chain hoist (DPM, DPH). It then falls from this height onto the probing rod. This procedure ensures that the battering ram always exerts the same force on the probe tip.
The number of blows per defined penetration depth is measured with the ram probing devices. The number of blows per 10 cm (probing) or 30 cm (SPT) penetration depth is plotted against the depth in the probing diagram. The probing diagram (stroke number diagram) is a step diagram or, for the SPT, a bar diagram.
This representation enables a simple assessment of the storage density. The evaluation is mostly only possible qualitatively , since various geotechnical conditions such as irregularity of the soil material, water content and friction of the probing rods influence the number of blows.
See also
Web links
- Project "Rammsonde" at the technical high school Hamburg-Farmsen