A cone penetration test is used to determine the geotechnical properties of soil. Cone penetration tests become one of the most widely used tests internationally for evaluating the properties of soil.
Cone penetration tests can be completed from the ground surface. The size of rig equipment used to test the soil varies from small portable rig to large-truck mounted rig.
The testing rig will push a steel cone about 32 mm in diameter into the soil. The cone steel will be pushed to a depth of 20 m or once it reaches a hard layer of soil. The cone steel will be equipped with a measuring system that measures the tip resistance and sleeve friction.
As the rig pushes the cone steel, the soil resistance for different layers is measured and recorded using a sensor at the cone steel tip. As the sensor at the tip recording the resistance force, sensors at the cone steel sleeve will record the friction resistance.
Cone steel can be equipped with a pore water transducer that can measure water pressure on the soil. These readings can be used to determine groundwater responses as the cone is pushed through the soils. The duration of cone penetration tests can range from 30 minutes to 3 hours. As the cone steel pushes into the ground, the measurements are sent back and recorded on a computer. Cone penetration test result is used by geotechnical engineers to determine the relative density for soil and the soil behavior type. Relative density and soil behavior are estimated from the cone penetration test cone tip resistance and sleeve friction.
Also, this test can be used to determine how the ground is likely to behave under different levels of earthquake shaking. Figure no:3 showing an example of cone penetration test measurements.