What is cone penetration testing?

Joe Hobbs, Lankelma Technical Manager.

The cone penetration test (CPT) involves pushing a cone penetrometer – the cone – on the end of a series of rods, vertically into the ground at a constant rate of 20mm per second, to depths of up to 100m.

The forces on the cone and the friction sleeve above are measured every 20mm to obtain detailed information about the soil conditions (CPT is suitable for a range of soil but cannot be used in rock).

Results are available almost instantly and can be used to determine soil parameters including soil type, soil density, insitu stress conditions and shear strength for use in geotechnical design. For instance, CPT results can be used directly for piled foundation design in sands and gravels.

 

 

The most common cones used are the standard cone and the piezocone, the latter measuring porewater pressure. You can see our full range here. A number of special cones are also available that can be run concurrently with the standard cone test to cope with different geological environments, to evaluate a huge range of soil parameters, as well as to take samples and install geotechnical instrumentation.

 

The advantages of CPT

• Greater delineation of strata, as readings taken every 20mm
• Repeatable, high quality and reliable results available in real time
• Electronic data transfer means more manageable data handling
• Test is quiet, produces no vibrations and creates minimal soil disturbance
• High productivity (up to 150m tested per day)
• Instant results allow on-site selection of the best locations for sampling, testing and monitoring
• Huge range of cones for geotechnical investigations, contaminated land studies and unexploded ordnance detection
• CPT can be used for obtaining high quality samples and installing instrumentation.

To learn more, watch our Introduction to CPT video

We’re here to help

We are always looking at new ways to help clients and partners, so please get in touch if you want to discuss how we can work together to share ideas and develop solutions to your geotechnical challenges.