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Towards uniformity of rotational events recording : initial data from common test engaging more than 40 sensors including a wide number of fiber-optic rotational seismometers

Kurzych Anna, Jaroszewicz Leszek R., Dudek Michał, Sakowicz Bartosz, Kowalski Jerzy

Opto-Electronics Review

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2021

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Vol. 29, No. 1

39--44

EN

Rotational seismology is one of the fastest developing fields of science nowadays with strongly recognized significance. Capability of monitoring rotational ground motions represents a crucial aspect of improving civil safety and efficiency of seismological data gathering. The correct sensing network selection is very important for reliable data acquisition. This paper presents initial data obtained during the international research study which has involved more than 40 various rotational sensors collected in one place. The key novelty of this experiment was the possibility to compare data gathered by completely different rotational sensors during artificially generated ground vibrations. Authors collected data by four interferometric optical fiber sensors, Fiber-Optic System for Rotational Events & Phenomena Monitoring (FOSREM), which are mobile rotational seismographs with a wide measuring range from 10⁻⁷ rad/s up to even few rad/s, sensitive only to the rotational component of the ground movement. Presented experimental results show that FOSREMs are competitive in rotational events recording compared with the state-of-the-art rotational sensors but their operation still should be improved.

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A test performance of optical fibre sensors for real-time investigations of rotational seismic events : a case study in laboratory and field conditions

Jaroszewicz Leszek R., Dudek Michał, Kurzych Anna T., Teisseyre Krzysztof P.

Opto-Electronics Review

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2021

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Vol. 29, No. 4

213--219

EN

Preliminary results of laboratory and field tests of fibre optic rotational seismographs designed for rotational seismology are presented. In order to meet new directions of the research in this field, there is clearly a great need for suitable and extremely sensitive wideband sensors. The presented rotational seismographs based on the fibre optic gyroscopes show significant advantages over other sensor technologies when used in the seismological applications. Although the presented results are prepared for systems designed to record strong events expected by the so-called “engineering seismology”, the described system modification shows that it is possible to construct a device suitable for weak events monitoring expected by basic seismological research. The presented sensors are characterized, first and foremost, by a wide measuring range. They detect signals with amplitudes ranging from several dozen nrad/s up to even few rad/s and frequencies from 0.01 Hz to 100 Hz. The performed Allan variance analysis indicates the sensors main parameters: angle random walk in the range of 3 ⋅ 10−8–2 ⋅ 10−7 rad/s and bias instability in the range of 2 ⋅ 10−9–2 ⋅ 10−8 rad/s depending on the device. The results concerning the registration of rotational seismic events by the systems located in Książ Castle, Poland, as well as in the coalmine “Ignacy” in Rybnik, Poland were also presented and analysed.

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Investigation of rotational motion in a reinforced concrete frame construction by a fiber optic gyroscope

Kurzych Anna T., Jaroszewicz Leszek R., Kowalski J. K., Sakowicz Bartosz

Opto-Electronics Review

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2020

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Vol. 28, No. 2

69--73

EN

This paper deals with an issue of a rotational motion impact on a construction and presents civil engineering applications of a fiber optic rotational seismograph named Fiber-Optic System for Rotational Events & Phenomena Monitoring. It has been designed for a long- term building monitoring and structural rotations’ recording. It is based on the Sagnac effect which enables to detect one-axis rotational motion in a direct way and without any reference system. It enables to detect a rotation component in the wide range of a signal amplitude from 10-8 rad/s to 10 rad/s, as well as a frequency from DC to 1000 Hz. Data presented in this paper show the behavior of a reinforced concrete frame construction on different floors. Several measurements were carried out by placing the applied sensor on different floor levels of a building. The laboratory and in-situ measurements confirmed that Fiber-Optic System for Rotational Events & Phenomena Monitoring is an accurate and suitable device for applications in civil engineering.

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Pilotażowe pomiary składowych rotacyjnych drgań sejsmicznych w rejonie LGOM

Fuławka Krzysztof, Pytel Witold, Mertuszka Piotr, Koziarz Eugieniusz

Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN

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2019

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nr 109

185--197

PL

Metody sejsmiczne są powszechnie stosowane w górnictwie, geofizyce oraz inżynierii lądowej. Aktualnie pomiary sejsmiczne prowadzi się głównie w zakresie rejestracji prędkości i przyspieszeń trzech składowych translacyjnych drgań. Wiedząc jednak, że pełny opis ruchu fali sejsmicznej, oprócz wspomnianych składowych translacyjnych, zawiera również trzy składowe rotacyjne, konieczne było podjęcie działań mających na celu pomiar i określenie charakteru tych ostatnich. Jeszcze do niedawna analiza rotacyjnych fal sejsmicznych prowadzona była wyłącznie w sferze teoretycznej, gdyż brakowało narzędzi umożliwiających rejestrację prędkości obrotowej cząstek gruntu, na poziomie często nieprzekraczającym ułamków μrad/s. Obecnie jednak sejsmologia rotacyjna jest zagadnieniem cieszącym się ogromnym zainteresowaniem, co wynika z pojawienia się na rynku czujników umożliwiających bezpośredni pomiar składowych obrotowych drgań sejsmicznych. Brak jest jednak kompleksowych opracowań w zakresie analizy tychże składowych w przypadku drgań indukowanych działalnością górniczą. W niniejszym opracowaniu przedstawiono wyniki pilotażowych pomiarów składowych rotacyjnych drgań. Analizie poddano zapisy wstrząsów górniczych oenergii w zakresie od 3 × 103J do 1,5 × 107J. Zarejestrowane wartości obrotu zostały skorelowane z zapisami drgań translacyjnych w celu określenia różnic w ich podstawowych parametrach takich jak czas trwania, częstotliwość i rozkład amplitudowy.

EN

A proper description of ground motions generated by seismic and paraseismic events requires gathering data of six components of seismic waves. Three of them, the so called translational waves, are well researched and identified. Unfortunately, until recently, the remaining three components named as rotational waves were generally estimated with the use of indirect methods based on theoretical calculations. This was related mostly with the lack of proper instruments for the recording of rotational seismic waves. Thus, rotational waves were not fully recognized thus far. Recently, several types of advanced instruments for direct measurements of rotation were invented. Based on the measurements of strong ground motions it was indicated that the amplitude of the rotational components in close distances from the seismic source can be significantly larger than expected. Apart from this, there is still a lack of analyses considering the characteristic of rotational seismic waves generated by induced seismic events. In this paper, the results of preliminary measurements of rotational motions generated by induced seismic waves were presented. Ground movements related with mining tremors were analyzed in terms of amplitude, frequency and duration.

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The laboratory investigation of the innovative sensor for torsional effects in engineering structures’ monitoring

Kurzych A., Kowalski J. K., Sakowicz B., Krajewski Z., Jaroszewicz L. R.

Opto-Electronics Review

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2016

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Vol. 24, No. 3

134--143

EN

The main objective of this work is to characterize the performance of an interferometric fibre sensor which has been designed in order to register rotational phenomena, both in seismological observatories and engineering constructions. It is based on a well−known Sagnac effect which enables to detect one−axis rotational motions in a direct way and without any reference system. The presented optical fibre sensor – FOSREM allows to measure a component of rotation in a wide range of signal amplitude form 10–8 rad/s to 10 rad/s, as well as frequency from 0 Hz to the upper frequency from 2.56 Hz to 328.12 Hz. The laboratory investigation of our system indicated that it keeps theoretical sensitivity equal to 2·10–8 rad/s/Hz1/2 and accuracy no less than 3·1–8 to 1.6·10–6 rad/s in the above mentioned frequency band. Moreover, system size that equals 0.36×0.36×0.16 m and opportunity to remotely control the system via Internet by special server make FOSREM a mobile and autonomous device.