Feasibility of the surface-wave method for the assessment of physical properties of a dam using numerical analysis

A three-dimensional finite difference elastic wave model was developed to estimate the feasibility of surface wave applications in geotechnical problems. The wave motions calculated by the developed program in this study compare favorably with well known analytic solutions. The surface wave motions calculated from layered-dam type structures could be interpreted as an infinite layered structure using dispersion curves, but a special source of high energy (frequencies lower than 10 hertz [Hz]) is needed to assess the physical properties at depths on the order of tens of meters. A high-energy source in the low frequency band, however, can result in structural damage to a dam, which would limit field applications of the program. The dispersion curves calculated from the surface wave motion of homogeneous and center-core type dam models would result in fatal errors in the model if the conventional infinite layer structure is used in their interpretation. This is because the surrounding materials and boundaries of a dam create some distortion in the dispersion curve of the surface wave. It is strongly recommended to use a three-dimensional inversion model for correct interpretation and estimation of physical properties of dam materials when using the surface wave application for dam inspection.