Monitoring of a retaining wall with innovative multi-parameter tools

Retaining walls are geotechnical structures that frequently interacts with roads, railway lines and motorways, playing a key role in the safety of transport networks in mountain areas. For this reason, monitoring activities aimed to assess the stability condition of these works are extremely important to guarantee the practicability of communication lines, especially during adverse meteorological conditions. In particular, the integration of automatic devices and advanced deep learning algorithms permits to implement early warning measures characterized by high accuracy and the reduction of uncertainties due to a statistical approach to the measure, which significantly improve the system performances. Finally, the remote control of physical entities through a web based platform permits to apply an all new Internet of Natural Hazards (IoNH) approach, which is to be intended as the implementation of IoT (Internet of Things) in the geo-related Hazard field. This paper presents a case study where a reinforced soil retaining wall was instrumented with innovative monitoring tools based on Modular Underground Monitoring System (MUMS) technology in order to control the displacements of the geotechnical structure together with the pore pressure and the temperature, applying Early Warning Procedures at the overcoming of predefined thresholds. In particular, two 15-meter long automatic inclinometers were installed on-site 3 meters apart, each of them composed of 15 multi-parametric tilt sensors spaced 1 meter along the vertical direction and one piezometer at a predefined depth. Among the several features presented by the innovative system selected for this case study, one of the most relevant was the synergic integration of two tilt sensors featuring different resolution and sensitivity, thus obtaining a redundant system, which has been fundamental in the correct evaluation of the results. Should this IoNH approach become diffusely applied, the costs of its implementation would reduce significantly and its valuable support would be beneficial for the whole geotechnical field.