Road Sinkhole Imaging with Ambient Noise Tomography: Fid-Bau Portal

Road Sinkhole Imaging with Ambient Noise Tomography

Wang, Yao / Tran, Khiem T. / Horhota, David

Seismic methods are often used for detection of pre-collapsed sinkholes (voids) under roadway for remediation to minimize the risk to the safety of the traveling public. While the active-source seismic methods can provide accurate subsurface profiles, they require closing the traffic flow for hours during testing and potentially cause sinkhole collapse due to ground perturbation by source excitation. To address these issues, we present a 2D ambient noise tomography (2D ANT) method for imaging voids under roadway. The method requires recording of vehicle-induced traffic noise using a linear array of geophones placed along a roadway. The cross-correlation function (CCF) is then extracted from traffic noise recordings and inverted to obtain velocity structures. Passing-by vehicles are assumed as moving sources along the receiver array for the forward simulation and inversion of the CCF. To demonstrate the method’s capabilities, it was applied to field noise data collected both pre- and post-grouting for assessment of a repaired sinkhole under US 441 highway, Florida, US. The pre-grouting result shows that the method is capable of resolving the subsurface S-wave velocity (Vs) structure and detecting a buried void. The post-grouting result suggests that the grouting operation was successful, and the void was sufficiently filled.