Dynamic Probing

We have over 45 years experience using penetrometer testing as part of a site investigation for characterising the strength of the ground and for the location of: solution features, areas of made ground, soft deposits, tunnels and other underground voids and cavities. The tests are based on BS EN ISO 22476-2: 2005 specifications.

probe1Dynamic probing 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 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 correlated directly to a standard penetration test ‘N’ value. The results are plotted on a graph, providing a visual interpretation of the different soil strata encountered.

Three types of DPT test are available: A DPSH Test in which a 63.5kg weight is dropped 750mm; a DPH Test in which a 50kg weight is dropped 500mm and a lightweight DPL test in which a 10kg weight is dropped through 500mm.

Rubber tracked or wheeled site investigation rigs are used ; they have a width of approx 850mm and require a level working space of about 3m x 2m and minimum headroom of 2.8m. Hand held equipment is used for the DPL test, for sites where rig access is problematic.

Results (blows vs depth) are plotted until the required depth has been achieved or at refusal (3 x 30 blows or 1 x 50 blows).

Get in touch

If you have any questions about our services or would like to discuss how we could help you, please get in touch using our contact form below. Please provide as much information as possible about the nature of your enquiry, particularly the purpose of the investigation, the site address and postcode.

Any existing or proposed site plans are useful and can be attached beneath the message box. Please provide a contact address, email and telephone number. We will get in touch as soon as possible.












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Southern Testing are continuing to work through the Coronavirus (COVID-19) emergency, including carrying out site work where it is safe to do so.

The Government have given express support to the Construction sector and have issued specific guidance for working on site. The Construction Leadership Council have also issued guidance.

We have revised our travelling and working practices to ensure that our staff are protected, and to meet the particular requirements of the guidance as well as our own risk assessments. The guidance and our working practices are under constant review.

Most site investigation work can be undertaken safely under the current restrictions.

We are committed to helping all our clients, old and new, during this difficult time. Should you have any site investigation requirements, or wish to discuss a particular project, please do not hesitate to contact us.