From Site Investigation
Dynamic probing involves driving a cylindrical sacrificial or fixed cone into the ground using a high frequency percussive hammer. The diameter and angle of the cone will depend upon the chosen method. For example the heavy or super heavy dynamic probe has an angle of 90 degrees. 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. The super heavy method is generally the preferred choice, with a drop weight of 63.5kg and a drop height of approximately 750mm.
Blows per 100mm are recorded and after every 1m section a torque reading is recorded, a further rod is then 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 directly correlated to a standard penetration test 'N' value. The results are plotted on a graph, providing a visual interpretation of the different soil strata encountered.