CPT, CPTU and DPSH Penetration Tests
In-situ geotechnical characterisation of soils without a borehole: static tests using mechanical, electrical and piezocone tips, dynamic tests and seismic cone testing for structures, foundations and slopes.
Static CPT and CPTE penetration tests
Static penetration tests (Cone Penetration Tests) provide cost-effective estimates of many geotechnical parameters in coarse-grained soils (excluding gravels) and fine-grained soils. The test is self-penetrating: a 35.7 mm diameter, 60° cone is pushed into the ground from the ground surface at a constant rate of 20 mm/s, connected to the pushing device by a string of rods.
With a Begemann-type mechanical cone, cone resistance qc, sleeve friction fs and their ratio—which provides an estimate of grain size—are recorded every 20 cm. With an electrical cone (CPTE), sensors continuously measure qc, fs and deviation from the vertical.
CPTU with piezocone
The piezocone records qc and fs at every centimetre of depth and measures pore pressure. This greatly enhances interpretation below the water table and makes it possible to identify thin layers with different permeability, which are key to estimating consolidation times.
DPSH and DL30 dynamic penetration tests
In a dynamic test, a conical tip is driven into the ground and the number of blows required to advance by a standard interval is counted. The method is quick and economical, and can identify the thickness of cover deposits over bedrock, the depth of any water table, failure surfaces on slopes and the consistency of the layers encountered. Dynamic penetrometers are classified by hammer mass as DPL, DPM, DPH and DPSH (super-heavy, M > 60 kg).
For sites with difficult access, we carry out DL30 tests using a lightweight dynamic penetrometer (30 kg hammer, 20 cm drop, with penetration recorded every 10 cm), built in accordance with DIN 4094.
Seismic cone
After the penetration test, the tip is replaced by a cone fitted with a three-component geophone array. In addition to qc, fs and pore pressure, in-situ Vs and Vp velocities are measured using the same principle as a downhole test, but without an instrumented borehole. Poisson’s ratio, Young’s modulus and dynamic shear modulus are calculated from the velocities.
Tests available
- CPT with mechanical cone
- CPTE with electrical cone
- CPTU with piezocone
- Super-heavy DPSH
- Lightweight DL30
- SPT
- Seismic cone
- Dilatometer tests
Images and results
Frequently asked questions
What is the difference between a static (CPT) and a dynamic (DPSH) test?
In a static test, the cone is pushed at a constant rate and cone resistance and sleeve friction are measured continuously; in a dynamic test, the cone is driven by hammer blows and the number of blows required to advance by a standard interval is counted. Static testing provides more detailed parameters; dynamic testing is quick, economical and also suitable for coarser soils.
When is CPTU piezocone testing needed?
When it is important to assess the behaviour of saturated soils below the water table: measuring pore pressure helps identify thin layers with different permeability, which are key to estimating consolidation times.
What does seismic cone testing provide?
In addition to qc, fs and pore pressure, it provides in-situ shear- and compressional-wave velocities (Vs, Vp), from which elastic moduli can be calculated without carrying out an instrumented borehole investigation.
What about areas with limited access?
We use the lightweight DL30 dynamic penetrometer, which is easy to handle and suitable for difficult-to-access locations.
Often combined with this investigation
Ready to get your project underway?
Send us the location and objective of the investigation: we will recommend the most suitable combination of methods and provide a detailed quotation.