Dynamic Penetration Testing

Dynamic Penetration Testing (DPT), commonly referred to as Dynamic Probing, is a fast and relatively low cost Ground Investigation method. It involves driving a cylindrical sacrificial or fixed cone into the ground using a high frequency percussive hammer. The cone is attached to a 1m section steel rod with a nominal diameter of approximately 35mm and graduation markings set at 100mm intervals. Depending upon the chosen method, the drop height can be adjusted.

Blows per 100mm are recorded and after every 1m section, a further rod is added and the process is continued until the probe refuses to penetrate the ground or the test reaches the required depth.

The results from this method can be correlated directly to a standard penetration test ‘N’ value. The results are plotted on a graph, providing a visual interpretation of the strengths of the different soil strata encountered.

Three types of DPT tests are available:

• A Dynamic Probing Super Heavy (DPSH) Test in which a 63.5kg weight is dropped 750mm
• A Dynamic Probing Heavy (DPH) Test in which a 50kg weight is dropped 500mm
• A Light Dynamic Penetrometer (DPL) test in which a 10kg weight is dropped through 500mm

All fieldworks are carried out in accordance with Eurocode 7 Part 2 Ground Investigation and testing (ISEN 1997-2:2007) and BS 5930.