Commonly, monitoring of dikes and revetments is performed visually after storm surges. Subsequently, conspicuous and visual damages are identified and recorded. If damages are considered to be hazardous for the dike resistance, renewal or maintenance of the affected dike section will be induced. However, the projected early warning system needs objective and - even more important - continuous dike monitoring, as the GeoPortal has to be provided with continuous data for further processing.
Therefore, the Institut fuer Textiltechnik (ITA) and the Institute of Hydraulic Engineering and Water Resources Management (IWW) of RWTH Aachen University develop an innovative monitoring system for sea dikes based on sensor fibers applied on geotextiles (smart geotextiles). Firstly, the requirements for a sensor-based monitoring system need to be defined and secondly, a comprehensive measuring system for smart geotextiles can be established in consideration of hydraulic and geotechnical conditions.
Figure 1: Schematic Description of the two Measurement Concepts
Within the project two different sensor concepts are considered: One type of fiber-based sensors identifies changes in pressure and deformation, another type measures humidity in the soil. The measured values are determined due to the elongation of the fibers (sensors) which results in a variation of their electrical resistance. The applied sensor types are cost-effective and can be produced using highly productive textile manufacturing processes. At ITA the Tailored Fibre Placement (TFP) – a special embroidery technology - is used, to apply the sensor on the geotextile.
Figure 2: Schematic Description of the TFP-Process Using Fiber-based Sensors
The IWW is conducting small-scale physical pre-tests in order to develop an efficient dike monitoring system. At the same time – also in IWW’s hydraulics laboratory - a large-scale model dike is designed to test and validate the installation of smart geotextiles and to develop further measurement concepts. In addition to laboratory testing, the developed dike sensors will be implemented in a real dike on a study site in Germany, which is purposed for the final phase of the project.
No matter on which scale, there will be continuous effort to process the acquired data in a way that allows integration into the GeoPortal, respectively into the early warning system (WP 5).
Figure 3: 3D-View of the Large-Scale Model Dike in the Hydraulics Laboratory