Seite - 682 - in Book of Full Papers - Symposium Hydro Engineering

4. DEFORMATION EARLY WARNING SYSTEMS A fiber optic distributed system for deformation relies on Brillouin sensing and provides early detection of ground settlements and heaves, local cracks and internal erosion. 4.1. APPLICATION: I-WALL LEVEE – NEW ORLEANS (US) The iLevees project ”Intelligent Flood Protection Monitoring Warning and Response Systems”, in the state of Louisiana, has the goal of providing an alerting and monitoring system capable of preventing early stage failure, both in terms of ground instability and seepage. The motivation for the monitoring system is to improve safety awareness, provide sensible information about levees’ status and conditions, before, during and after floods, and to avoid the tragic events like the ones that occurred following Hurricane Katrina in 2005. The project had the goal to monitor the levee wall, deformation and shear, and the surrounding soil, movements and water infiltration / seepage. The particularity of the project was the installation technique adopted for the levee wall integration. In order to provide a good transfer of the acting forces from the wall to the sensor itself a good bonding strength shall be given: to do this it was decided to “cut” a groove all along the installed section, where the sensing cable was deployed and sealed by means of specific episodic resins (Fig. 8). Fig. 8 Installation of sensor in a groove, on top of the levee wall section and in a trench For the surrounding soil a more common ground embedding technique was chosen on the base of our previous returns of experience. Sensors are embedded between 0.5 and 1 m below the ground level, after compacting the trench, the sensors are deployed and covered with soft filling material. After this 682