Project detail

TUNNEL

Type of structure

Tunnel

Location

Italy

Why monitoring

  • Assess the structural behaviour induced by landslide movements
  • Control in real time the structural safety by investigating the lining ovalization
  • Notify any anomalous condition that may occur during the tunnel service life by setting alerts/notifications
  • Set thresholds values to the expected tunnel deformation to preserve the safety service conditions
  • Plan effective maintenance interventions

Interventions in synthesis

  • Type of devices : Clinometers
  • Number of sensors : c.a. 800
  • Installation time : October 2016
  • Analyzed data : Tunnel segments rotation

Goals

Due to their unique design and construction, tunnels call for rigorous structural health monitoring (SHM) programmes both during construction and operation phases. Indeed, their continuous monitoring can mitigate potential hazards, ensure better performance and facilitate in-depth understanding of the overall structural behavior.

The monitored infrastructure is a double-arch 2 km long tunnel located in Italy. The tunnel has been instrumented to monitor the effects of an active landslide on the lining structural deformation. The monitoring system consists of a MEMS clinometers network installed to control and quantify the evolution of the transversal tunnel sections deformation where the movements induced by the landslides are more onerous. Short and long-term tunnel behaviours have been reproduced through finite element modelling in order to represent the structure pre-existing stress state at the time of installation of the monitoring system. The evolution of the landslide-induced movements have been modeled based on the information collected though the monitoring system at regular intervals.

The tunnel has been equipped with a sequence of longitudinal and transversal clinometers channels. The devices network can detect ovalizations up to a few millimetres over a 15 m diameter tunnel. The acquired data are stored on a cloud platform where specific data processing algorithms analyse clinometer readings and provide an efficient real time tunnel monitoring. The tunnel ovalizations are compared in real time with a set of alerts limits representing an increasing danger level, triggering automatic alerts notifications.