Nondestructive Characterization of Open Cracks in Tunnel Lining Concrete by Surface Waves

The authors have been studying on establishing an efficient method for evaluating the health of tunnel lining concrete. Although there are many research works on nondestructive testing method using seismic or ultrasonic waves, almost all methods treated P-waves. Since P-waves are difficult to observe when both source and receivers have to be on the concrete surface, we considered using surface waves. As the results of physical model experiments, we found that the surface wave velocity could be used as an index of concrete soundness. We also found that the amplitude attenuation of surface waves passing an open crack could be used to determine the depth and the dip direction of the crack.