Geo-characterization using waves - Principle to application

Both elastic and electromagnetic waves have been widely used in science, medicine, biology, and engineering. In soil mechanics and geotechnical engineering, the applications of waves have been significantly increased. The objective of this paper is to introduce the principle and applications of wave propagation for geotechnical engineering. Both transmission and reflection methods of waves are used for the characterization of geo-materials and geo-structures. First, the essential concepts of elastic and electromagnetic waves are discussed. Second, the reflection properties are compared. Third, the applications of transmitted and reflected waves are discussed for the characterization of geo-materials and geo-structures. The void ratio of fully saturated soils can be estimated by combining compressional and shear waves as well as electrical resistivity. In addition, the electrical resistivity is used for evaluating the slime thickness in drilled shafts. The reflected guided waves provide the integrity of the slender structures. Furthermore, the polarization of the reflected waves is used for identifying the geo-properties near the reflected zone. Finally, the combination of the transmitted and reflected waves is used for evaluating the energies transferred into the rod head and the cone tip during dynamic penetration.