f Further development of the CPT method

In progressive soil mechanical examination and reconnaissance geological surveys the Cone Penetrating Test (CPT) is widely applied. Special features of the geological structure of Hungary necessitated the further development of the method and the enlargement of measured physical quantities. Thus the environmental examinations gained a new too) which possesses promising perspectives due to objectiveness and in-situ applicability of the method. In the beginning, the method consisted of measurement of mechanical parameters: the cone pressure necessary for penetrating the measuring probe ending in a standardized cone into the soil, and the so-called total pressure (inside the hydraulic system). Later nuclear measuring procedures have been adopted from well logging: natural gamma, gamma-gamma and neutron-neutron intensities are measured. These nuclear measurements can be carried out even in the drilling rod. The measured parameters provide information on independent rock mechanical characteristics: cone pressure on the breaking strength on the layers penetrated, natural gamma intensity on the clay content and the neutron-neutron on the water content (more precisely on the hydrogen content). Recently we are able to measure the resistivity of the surrounding of the probe pressed down into the soil.