ABSTRACT
This chapter presents the application of multi-geophysical approach for detection of a cavern between two lanes of the Rijeka - Zagreb highway in Croatia. Applied geophysical methods were Ground Penetrating Radar (GPR) and seismic refraction method. The chapter provides basic principles of both methods as well as the results of investigation works which consisted of 21 GPR profiles and one seismic refraction profile. In order to determine the size and dispersion of the cavernous system, geological and geophysical investigations were carried out. As a consequence of karstification, a large number of karstic features, such as caverns, are linked with engineering activities and directly influence existing infrastructure, especially national highways and roads. At the location of the cavern, geophysical investigation consisted of seismic refraction investigation and ground penetrating radar investigations. During construction of cavern a total amount of fine-grained concrete which was used for filling of cavern was 130 m3.
