TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina A1 - Glötzl, R. ED - Boller, C. T1 - Temperature-corrected determination of mechanical deformations in geotechnical structures using Brillouin-based fiber optic sensors N2 - Structural Health Monitoring based on distributed Brillouin measuring techniques has been playing bigger and bigger role for applications in large-scale critical structures over the last decade. The Brillouin sensing techniques make use of low-loss single-mode optical fibers as distributed sensors allowing compound strain and temperature profile discrimination along the measured section even over several tens of kilometers. Thereby, the measured Brillouin frequency shift (BFS) features much stronger dependence on the longitudinal strain in the sensor fiber than on the temperature distribution along the fiber optic sensor. By detection of slight structural changes in monitored civil structures, such as dams, pipelines and tunnels, the influence of temperature on the measured BFS cannot be neglected. In simple cases of fiber optic sensors embedded deeply enough into earth structures no significant temperature gradients caused by weather conditions such as sunrays could be observed. The temperature contributes here only to the signal offset and the local mechanical deformations arisen due to soil displacement can be read directly from the distribution of the BFS. Also special cable solutions for separate determination of temperature and strain have been tested by us under field conditions. The use of two separate optical fibers for strain and temperature detection limits the spatial resolution and measurement accuracy in the determination of both physical quantities. In search of the optimal sensory solution for monitoring of mechanical deformations taking into account the temperature component in the measured signal the use of so called nonzero dispersion-shifted fibers has been investigated in several laboratory tests. Due to different doping concentration in the core new resonance acoustic modes can propagate in such optical fibers which results in multipeak structure in the Brillouin gain spectrum (BGS). The appearance of more than one resonance peak in the BGS offers the possibility to realize simultaneous measurement of longitudinal strain and temperature by analysis of applicable BFSs as function of both physical quantities using only one low cost optical fiber. T2 - EWSHM'12 - 6th European workshop on structural health monitoring 2012 CY - Dresden, Germany DA - 03.07.2012 KW - Structural health monitoring KW - Brillouin scattering KW - Distributed sensor PY - 2012 SN - 978-3-940283-41-2 VL - 1 SP - 417 EP - 422 CY - Berlin AN - OPUS4-26311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nöther, N. A1 - Wang, S. A1 - Wosniok, Aleksander A1 - Glötzl, R. A1 - Schneider-Glötzl, J. ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Distributed Brillouin sensing in optical fibers: Soil displacement monitoring using sensor-equipped geogrids N2 - This paper reports on the application of distributed Brillouin fiber optic sensing to the monitoring of geotechnical structures. The presented approach to Brillouin sensing offers an alternative to the common pulse-based measurements by using the frequency domain analysis. The focus of the research and field-testing work is to collect reliable structural health monitoring data from large-scale structures while preserving the System’s versatility in terms of being suitable for different application environments (soil structures, foundations, concrete construction works, pipelines etc.) and its robustness in being well functioning in harsh environments. Upon reviewing the presented application test, it is concluded that Brillouin frequency domain based monitoring, when applied to geotechnical structures, is capable of providing accurate strain readings representing deformations of the soil body, and reliable temperature readings for generating temperature profiles of the entire structure. An overview of the frequency domain analysis of Brillouin sensing and its digital implementation is given, along with the experiences and insights drawn from an open field test of sensor-equipped geogrid mats. T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 09.12.2013 KW - Structural health monitoring KW - Distributed sensing KW - Fiber-optic sensing KW - Brillouin sensing KW - Strain and temperature measurements KW - Sensor-equipped geosynthetics PY - 2013 SN - 978-962-367-768-4 SP - 290 EP - 295 AN - OPUS4-29914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiele, E. A1 - Erth, H. A1 - Helbig, R. A1 - Werth, K. A1 - Glötzl, R. A1 - Schneider, J. A1 - Nöther, Nils A1 - Wosniok, Aleksander A1 - Krebber, Katerina A1 - Schlurmann, T. A1 - Saathoff, F. T1 - Sensitive Textilstrukturen zur Deichüberwachung T2 - BAUTEX 2008, 8. Sächsisches Bautextilien-Symposium "Bauen mit Geokunststoffen" CY - Chemnitz, Deutschland DA - 2008-01-24 PY - 2008 SP - 1 EP - 5 CY - Chemnitz AN - OPUS4-17448 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Glötzl, R. A1 - Schneider Glötzl, J. A1 - Wosniok, Aleksander A1 - Krebber, Katerina A1 - Krywult, L. ED - Wintera, J. ED - Kosik, A. ED - Wity, A. T1 - Optical distributed sensing systems and possible applications in geotechnical measuring N2 - In comparison with traditional measuring Systems (pressure cells, piezometers and inclinometers which produce only point measurements) fibre optic sensors are well suited for spatiallydistributed monitoring purposes. The very tiny optical fibres of a diameter of less then 1 mm can operate as sensors in strong electromagnetic fields, under “harsh” explosive and Chemical environments and under ionizing radiation. T2 - XIV Dam monitoring international conference 'safetyof dams - new challenges' ('Bezpieczenstwo zapór - nowe wyzwania') CY - Walbrzych, Poland DA - 13.06.2011 KW - Fibre optic sensor KW - Spatial distributed sensor KW - Polymer optical fibre (POF) KW - Glass optical fibre (GOF) KW - POF OTDR KW - Brillouin sensor KW - BOTDA KW - BOFDA KW - Fibre Bragg grating (FBG) KW - Geosynthetics KW - Geotxtiles KW - Technical textiles PY - 2011 SN - 978-83-61102-53-3 N1 - Serientitel: Monografie - Instytutu Meteorologii i Gospodarki Wodnej – Series title: Monografie - Instytutu Meteorologii i Gospodarki Wodnej IS - Chapter 6 SP - 173 EP - 180 AN - OPUS4-24066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -