Structural Health Monitoring of Expressway Embankment Using Distributed Acoustic Sensing (DAS)

Structural Health Monitoring (SHM) is a method of evaluating structural soundness through monitoring. SHM has been widely applied to various engineering structures such as bridges and buildings. However, there are some problems that must be solved in order to apply SHM to expressway embankments. If there is no deformation or damage, the soundness of the road embankment cannot be evaluated by close visual inspection. Borehole investigations cannot assess the soundness of the entire embankment. And the length of the road embankment is long, making it difficult to monitoring in service. Geophysical exploration is an effective method for evaluating the soundness of expressway embankments over time, but its exploration requires traffic control. Therefore, new vibration measurement tools are needed to make measurements safely and without restrictions such as regulatory time. One of the candidates is Distributed Acoustic Sensing (DAS) measurement technique. That technique is applied for the inspection of the soundness of expressway embankment without any traffic control. We carried out comparative data acquisition of passive surface wave method using DAS and linear array velocity meters (geophone) at the embankment of Chuo expressway in Nagano Prefecture, Japan. DAS results provided consistent dispersion curves with geophones. The results imply that DAS can be applied to SHM of expressway embankment.