New Methods to Seismic Monitoring: Laboratory Comparative Study of Michelson Fiber-Optic Interferometer and Pneumatic Measurement Systems

Abstract

New possibilities of vibration monitoring can be found in completely different physical approaches, where all measuring technology is currently based on sensors in the electrical domain. This paper presents two different promising alternative approaches to vibration measurement, specifically in the field of fiber-optics and pneumatic sensors. The proposed solution uses a Michelson fiber-optic interferometer designed without polarization fading and with operationally passive demodulation technique using three mutually phase-shifted optical outputs. Experimentally developed sensor systems for the registration of anthropogenic seismic phenomena were complemented by standard instrumentation for measuring seismicity used as a standard. The measurement was performed under simplified conditions using a calibrated stroke as a source of dynamic loading. In addition to alternative systems, the paper also presents the results of recalculation of the measured values in a time domain and basic relationships for the conversion to basic units derived from the SI (International System of Units) system and used internationally in the field of seismic engineering. The results presented demonstrate that even systems operating on a different physical principle have great potential to replace the existing seismic devices. The correlation coefficients for both sensory devices were high (above 0.9) and the average deviations from the measured values of the amplitude of the oscillation velocity did not exceed the value of 0.02, neither with the fiber-optic or pneumatic sensor.

Comparative In Situ Study of Dynamic Load Generated by Gravel Piles Measured by a Fiber-Optic Interferometer

“…Two BRS32 seismic stations, see Figure 1 , were used as the reference instrument at two sites: these had also been used by the authors in previous studies aimed at comparing results obtained from alternative approaches to vibration measurement [ 1 , 6 , 8 ]. The special mobile compact datalogger had originally been developed for the Institute of Rock Structure and Mechanics of the CAS of the Czech Academy of Sciences, v.v.i.…”

“…Other achievements include the measurement of vibration during landform compaction with a vibratory roller [ 8 ], the study of harmonic vibration in comparative measurements of alternative equipment and instrumentation for seismic monitoring [ 9 ], and research on vibration associated with works and construction technologies in brownfield areas [ 10 ]. Last but not least, the authors presented a description of new methods for seismic monitoring, namely a laboratory comparison of fiber-optic sensors with pneumatic measurement systems [ 1 ].…”

“…The results of previous experimental studies dealing with the use of different physical principles in the monitoring of the effects of engineering seismicity have confirmed the applicability of the alternative devices under development, especially in the frequency domain. The logical follow-up was to focus on the time domain, where a first (laboratory) experiment performed in a homogeneous environment with a calibrated strike yielded interesting and thought-provoking results [ 1 ]. This served as the impetus for a larger-scale follow-up experiment, in which vibrations generated during the implementation of in situ gravel piles were monitored using standard seismic instrumentation, which acted as a reference in the experiment, and by an optical interferometric sensor under development.…”

Special Issue “Optical Fiber Interferometric Sensors: New Production Methodologies and Novel Applications”

“…Stolarik et al contributed to this SI with a report on promising alternatives for vibration measurements, with an optical fiber Michelson interferometer, designed with passive demodulation technique using three mutually phase-shifted optical outputs [4]. The performance of this device was compared with existing seismic devices, and the results demonstrate its great potential, with correlation coefficients above 0.9, and average deviations of the amplitude of the oscillation velocity around 0.02.…”

“…The performance of this device was compared with existing seismic devices, and the results demonstrate its great potential, with correlation coefficients above 0.9, and average deviations of the amplitude of the oscillation velocity around 0.02. [4].…”