Geotechnical sampling or Standard Penetration Test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil. 

The test will measure the resistance of the soil strata to the penetration undergone. 

The test provides an indication of the relative density of granular deposits, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great advantage of the test is that it is simple and cost effective.