Smart aggregate-based seismic stress monitoring system using a specially designed charge amplifier

The potential of smart aggregate for seismic stress monitoring has been identified, but only moderate dynamic stress of relatively high frequency can be measured reliably due to the limitations of conventional charge amplifiers. To improve the performance of smart aggregate-based monitoring systems, a charge amplifier was designed especially for the demands of seismic stress monitoring. Its performance was tested in the low frequency range down to 0.05 Hz with high charge input up to 2 × 10 ⁷ pC representing stress up to 100 MPa by feeding it frequency-sweep charge signals. With the specially designed amplifier, the performance of the smart aggregate-based monitoring system was tested in both frequency-sweep and amplitude-sweep loading tests, and the influence of lead zirconate titanate depolarization was evaluated at static loads of 4.8, 14.4, and 24 MPa. The results show that the demands of seismic monitoring with a smart aggregate-based system can be satisfied, and that the sensitivity of the system remains constant under dynamic loads up to at least 45 MPa.