NATM tunnel monitoring

Tunnel monitoring is the process of continually measuring and assessing the structural stability of tunnels, both during construction and over their operational life.
In the New Austrian Tunneling Method (NATM) — also known as the Sequential Excavation Method (SEM) — tunnel monitoring is crucial. Developed in Austria in the 1960s, NATM involves staged excavation, where the surrounding rock or soil temporarily supports the tunnel until the permanent lining is installed. Monitoring at every step ensures the safety of workers and the stability of the tunnel structure.

NATM tunnel monitoring specifically involves the continuous tracking and analysis of various factors that impact a tunnel’s stability. During the construction phase, monitoring typically focuses on key parameters such as tunnel convergence, ground settlement, groundwater pressure, and rock stress.

• Tunnel convergence measures changes in the tunnel’s diameter during excavation, indicating the stability of the surrounding rock.
• Ground settlement refers to any downward movement of the ground surface due to compaction or other factors, helping to identify potential issues.
• Groundwater pressure is tracked to assess the risk of water infiltration, which can lead to erosion and soil instability.
• Rock stress indicates forces acting on the surrounding rock, which impacts overall safety.

Key Instruments for NATM Tunnel Monitoring and Structural Health

During both construction and operational phases, a range of instruments for tunnel monitoring are essential. These include inclinometers, extensometers, load cells, and strain gauges, each designed to perform in the challenging underground environment. The data collected through these instruments is integral to structural health monitoring (SHM), supporting engineers in making timely decisions that enhance tunnel safety, minimize maintenance costs, and extend tunnel lifespan.

With SISGEO’s reliable instruments for NATM tunnel monitoring, clients can depend on accurate data to maintain safe and stable tunnel operations for years to come.