Crackmeters and joint meters
Crackmeters and joint meters are devices used in structural monitoring to measure cracks and joint movements in buildings, tunnels, bridges, dams, and other structures. These instruments provide information about the behaviour and stability of the monitored structure over time. Both crackmeters and joint meters play an important role in structural health monitoring (SHM) and assessment. By monitoring cracks and joint movements, potential structural issues can be detected early, allowing for timely maintenance or repairs to ensure the safety and integrity of the monitored structure. For all these reasons, the application of crack meters and joint meters is crucial in dam rehabilitation.
The simplest method to measure a movement of a crack is to use the tell-tale crack meter. It is composed of two transparent plastic plates, one with a graduated grid and one with a reference cross, mounted over the crack or joint.
Tri-axial mechanical joint meters are often used in application where automatic readings are not requested and where the engineer can take the readings with a dial gauge directly on the instrument. Tri-axial joint meters are frequently installed in concrete dam projects to monitor construction joints.
Electrical crackmeters and vibrating wire crackmeters are available for accurate and automatic monitoring. Offered with both potentiometer and vibrating wire sensor technology, they can also be installed with special supports in 2D or 3D configuration. They are IP68 protected, and so suitable for projects that request waterproofing (e.g. dams, piers, tunnels, etc.).
Embedment jointmeters are often installed in concrete dams where construction joint monitoring is essential. Embedded between two concrete blocks of the dam, movements occur in the joint are detected.
The wire deformometers is a gauge able to detect relative movements between two points at a maximum distance of 10m connected with a stainless steel rope. The installation is very simple: install the instrument body on one point, extend the wire to the second point and fix it to the reference anchor.
The Wire crackmeter is similar to the wire deformometers. It is used when distance between the points to monitor is larger than 10m and when a strong and rugged instrument is required. It is basically composed by a stainless steel instrument box that houses the sensor, a steel wire and a reference anchor. This kind of instrument is widely used to monitor landslides and large rifts.
Vibrating wire deformation meters are designed to be installed in RCC dams to monitor the expansion of induced joints.