Multiplexed fiber optic pressure and vibration sensors for hydroelectric dam monitoring

The use of fiber optic sensors in the civil structures arena is increasing, particularly in the instrumentation of high-performance structures. However, the physical configurations of many such sensor platforms necessitates the use of fiber optic sensor multiplexing. Typically fiber optic sensor multiplexing has involved the grouping of similar or identical sensors along single transmit/receive fiber optic leads coupled with some form of time-, phase-, frequency- or polarization-based multiplexing. Based on work on embedding sensors into multiple large civil structures, the authors feel that multi-media sensors (i.e. fiber optic sensor configurations in which multiple parameters of interest can be measured simultaneously with a single fiber) represent a potentially better method of sensor multiplexing. Results based on sensor multiplexing and interrogation of pressure sensors and vibration sensors used in the health monitoring of a modest-sized hydroelectric dam are described.