DPSH vs SPT: Choosing the Right Penetration Test for Your Site Investigation

SPT and DPSH are both dynamic penetration tests, but they answer different questions. The right choice depends on what your design needs to know about the ground and on the budget of the investigation.

Side by side

• Sampling: SPT recovers a disturbed sample; DPSH does not.

• Resolution: SPT gives a value at discrete depths, typically every 1 to 1.5 m; DPSH records every 200 mm.

• Productivity: DPSH covers more points per day because no borehole is needed.

• Standards: SPT under ASTM D1586 or ISO 22476-3; DPSH under ISO 22476-2.

• Design use: SPT correlations are widely published; DPSH results usually need site-specific correlation to SPT or CPT.

The best answer is often both

A few boreholes with SPT establish stratigraphy and provide samples. A grid of DPSH probes then maps lateral variation and finds the bearing layer between them. The combination lowers cost while keeping classification reliable, in line with the Eurocode 7 principle of using complementary investigation methods.

Keep in mind that correlations between N20 and SPT N-values depend on soil type and on the energy of each system. Verify them against paired tests on your own site.

Need both rigs?

Diamond Drill supplies equipment for both SPT and DPSH. Contact our technical team and request a quote for the right configuration.