Dynamic Probing

A quick and effective method of determining the ground’s resistance to penetration.

Dynamic probing is a fast, cost-effective way of determining ground conditions, particularly on sites with difficult access, limited headroom or steep slopes. A steel cone attached to a steel rod is driven into the ground using a trip hammer of a certain weight, that is dropped over a certain height. The hammer is typically on a crawler-mounted rig. Every time the rod is driven 100 millimeters into the ground, a record is made of the number of blows it took to get there. This method is not to be confused with Dynamic Cone Penetration (DCP) testing.

Unlike Trial Pitting or Borehole Drilling, no soil samples are collected during dynamic probing. The test is designed to provide a profile of the ground’s resistance to penetration. Variations in the penetration rate allows for the identification of boundaries between strata of different densities and driving resistance and can identify soft areas and voids such as dissolution features or mine workings. The results can also be correlated to a standard penetration test (SPT) ‘N’ value.

As an added benefit, piezometers can be installed with dynamic probing equipment to monitor groundwater levels. Similarly, gas monitoring tubes can be installed in or adjacent to contaminated sites with environmental concerns.

Dynamic probing tests are typically undertaken from relatively compact rubber tracked or wheeled site investigation rigs such as window sampling rigs or portable pneumatic units. Dynamic Probing can be carried out using various rigs differing in size and drop depth. The choice of rig is most often dependent on the accessibility and required test depths:
– DPL – Dynamic Probe Light: a 10kg hammer dropped 500mm;
– DPH – Dynamic Probe Heavy: a 50kg hammer dropped 750mm;
– DPSH – Dynamic Probe Super Heavy: a 63.5kg hammer dropped 500mm.