DIGUE 2020 : dike monitoring
25 february 2021
Client : INRAE
Location : France, Provence Alpes Côte d’Azur
Type : Monitoring of physical parameters over the entire structure (temperature, suction, resistivity, humidity, pore pressure, pH and salinity in the soil), optic fiber acoustic measurements for the internal flows characterization in the dike.
Project objectives :
Cementys teams took part in the Digue2020 project which goal is to create a research platform on the Mediterranean coast. The objective is to quantify the sea’s action impact on the structure in the short, medium, and long term.
This collaborative research project brings together four research laboratories: INRAE, Cerema, Gustave Eiffel University and ESPACE, as well as a syndicate managing the seawalls, SYMADREM. Our engineers were involved during the design phase and during the construction of the dyke to ensure the installation of various measurement sensors.
Internal erosion is one of the major causes of failure of hydraulic structures. It is induced by internal flow phenomena that cause the detachment of soil particles and their transport in the body of the structure and its foundation.
The current methods of inspection of such infrastructures do not allow to detect the appearance of this phenomenon within the structure.
Our solutions :
As traditional monitoring tools are not efficient, new detection techniques based on the use of acoustic sensors are being studied. These methods are based on measuring the acoustic energy released during the phenomenon of internal erosion within the dike. The objective is to characterize the acoustic signature of turbulent flows using fiber optic sensors based on Distributed Acoustic Sensor (DAS) technology.
In the longer term, this new non-intrusive approach could be used to facilitate the monitoring of dikes and their foundations to prevent the risk of breach failure from which this type of structure suffers.
The innovation of this research platform lies in the use of soil treated with lime for the construction of the dike. To study the behavior of this material in a marine environment, several blocks with different compositions and compaction characteristics have been defined. The instrumentation set up during the construction allows the comparative follow-up of these blocks via physical parameters representative of the evolution of the structure.
The sensor installation phase was completed in the summer of 2020. Several laboratories and on-site test campaigns in partnership with the INRAE have since been conducted to characterize the acoustic signature associated with the appearance of internal flows.