TY - CONF A1 - Jentsch, H. A1 - Schwartz, A. A1 - Basedau, Frank A1 - Bazrafshan, K. A1 - Döring, H. A1 - Großwig, S. A1 - Hofmann, Detlef A1 - Kowalle, G. A1 - Kusche, Nadine A1 - Lorenz, R. A1 - Pfeiffer, T. A1 - Sadaghiani, M.R.S. A1 - Scholz, E. A1 - Senze, A. A1 - Tkachenko, Viktoriya A1 - Witt, K. 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 - Detection of slipping soil areas with embedded tiny vertical sensing rods N2 - Critical soil zones where large areas along a shear joint might begin to slip should be recognized. In order to avoid damage, monitoring of such unstable zones is necessary. First, soil movements must be detected as early as possible, second, the amount of deformation should be estimated. Because geodetical methods do not provide information about deformation in the underground in different depths, the only way to come to information from possible shear zones is the installation of deformation measurement systems. A special installation method was developed to bring a long-gauge length measurement system into a borehole and transfer data of soil deformations into an installed sensing rod. The mostly vertically installed sensing rod has an outer diameter of 3 mm to 6 mm and contains several optical fibres. One fibre provides integral strain information along the whole length of the rod. To get this information, the phase difference between the fibre input and output is measured and the change of the total length of the fibre can be derived. This easy and cheap online sensing system delivers an early warning of soil deformations respectively possible slip as well as landslides. In case of warning, the second sensing system based on Fibre Bragg Grating sensors located close to the expected shear zone purposefully. It records resulting deformations in detail. In this study, three main objectives were achieved: a) development of tiny pultruded sensing rods with integrated optical sensor fibres, b) installation technology which enables the integration of the sensing rod during drilling and pile driving, and c) development of a stiff but elastic racking material to fix the rod in the soil and to transfer soil deformation into the stiffer sensing rod. These three aspects including the fibre optical measurement systems are described; results from Press Deformation Test (PDT) are presented. Test results of the fibre optical online system are compared and evaluated with the results of conventional inclinometer measurements as well as numerical modelling. An outlook for further possibilities of usage of this monitoring system is given. 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 - Soil stability monitoring KW - Optical fibre strain-sensor KW - Geotechnical soil stability KW - Soil deformation modelling PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 9 AN - OPUS4-29915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang A1 - Woschitz, H. A1 - Lienhart, W. ED - Jaroszewicz, L.R. T1 - Field examples for optical fibre sensor condition diagnostics based on distributed fibre-optic strain sensing N2 - Fibre optic sensors for monitoring in safety-relevant structures have to be validated in order to proof their reliability under typical structural load conditions. The reliable use of optical fibre sensors depends strongly on an appropriate and qualitative application. Diagnostics of the physical condition of embedded and surface-applied fibre optic strain sensors are demonstrated on field examples. Distributed strain measurement based on Rayleigh backscattering is used to determine breakage of the fibre, interface adhesion problems and to identify application related strain transfer mechanisms. T2 - EWOFS 2013 - 5th European workshop on optical fibre sensors CY - Kraków, Poland DA - 19.05.2013 KW - Fibre Bragg grating KW - Rayleigh backscattering KW - Condition diagnostics KW - Strain KW - Strain transfer PY - 2013 SN - 978-0-81949-634-8 DO - https://doi.org/10.1117/12.2025567 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8794 IS - Paper 8794 - 181 SP - 879433-1 EP - 879433-4 AN - OPUS4-28570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -