Guided wave attenuation in cylindrical bars surrounded by soil

In ultrasonic guided wave NDE of a structure surrounded by a solid medium, guided wave attenuation caused by energy leakage into the medium is an important property that has a significant effect on the inspection range and/or signal-to-noise (SN) ratio. In this work, guided wave attenuation in cylindrical steel bars surrounded by soil was studied through calculation. Characteristic equations of guided waves (L, T and F modes) in cylindrical bars surrounded by solid media are presented, and the attenuation dispersion curves of L(0,m) and T(0,m) modes of cylindrical steel bars surrounded by soil are computed and analyzed for various material properties of soil (density, bulk longitudinal wave velocity and bulk shear wave velocity). The results indicate that selecting an appropriate guided wave mode and frequency with consideration of the attenuation and the soil material properties is essential for proper ultrasonic guided wave NDE of bars surrounded by soil.