scope:

This part of ISO 22476 deals with the equipment requirements for, execution of and reporting on the penetration test to complement direct investigations (e.g. ISO 22475-1).

NOTE This part of ISO 22476 fulfils the requirements for standard penetration testing as part of geotechnical and testing in accordance with EN 1997-1 and EN 1997-2.

The standard penetration test aims to determine the resistance of soils at the base of a borehole to the dynamic penetration of a split barrel sampler and the recovering of disturbed samples for identification purposes (SPT). In gravelly soils and in soft rocks a solid cone is also be used (SPT(C)).

The standard penetration test is used mainly to assess the strength and deformation parameters of cohesionless soils, but some valuable data may also be obtained in other soil types.

The basis of the test consists in driving a sampler by dropping a hammer of 63,5 kg mass on to an anvil or drive head from a height of 760 mm. The number of blows (N) necessary to achieve a penetration of the sampler of 300 mm (after its penetration under gravity and below a seating drive) is the penetration resistance.