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| | Abstract | | The infrastructures in civil engineering have characters of long distances. If we use some sensors to detect any unusual changes in structures, a huge number of high sensitivity sensors are needed. The fiber optic DAS (Distributed Acoustic Sensor) behaves like dense distributed seismometer array at a few meter intervals along the optical fiber elongation. To evaluate usefulness of the DAS for the civil engineering purposes, we carried out the evaluation test f DAS. We obtained a little lower S/N than geophone, but it can be partly due to sensitivity directional differences between two sensors. Three optical fibers with/without stainless steel casing gave almost the same quality data. The sensitivity orthogonal to fiber is weak but detect vertical incident P wave. DAS can provide continuous vibration data at every a few meters along 20 km distance in real-time. Through the test, we can conclude that the seismic use of optical fiber DAS could give satisfactory information for the civil engineering purpose. If we use this DAS technology for the continuous monitoring of road or embankments, we can supply useful alerts to social infrastructure owners during heavy rains, flooding or instantaneous landslides. |
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