Measuring deformation: control based on risk

Deformation and subsidence are notorious side-effects of construction work. Normally, all possible effects are calculated in the design stage and a construction method is selected that limits these effects. But these calculations offer no guarantees. Strukton Survey & Monitoring has a variety of methods to verify calculations and, if necessary, to adjust the construction process.

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Integration of measurement solutions

The integration of measurement solutions in the design phase enables arbitrary parameters to be determined more precisely. The natural behaviour of objects with respect to water levels, tides, temperature and other natural conditions, for example, can be determined by means of test measurements, practical testing and/or timely baseline measurements. This makes the prediction of behaviour and the interpretation of data during realisation more accurate.

Project team

In the design stage, the project team determines which measurement methods will be used, and how they will be used. The design requirements are the guiding principle for the measurement method, construction requirements, measurement frequency, signalling & threshold values, the communication of alerts, and the reporting of measurement data. Fully automatic alerting and reporting is possible, if required by the preconditions of the work.

Measuring distance

Deformation is measured by measuring distance or difference in distance. Automatic and manual measurement systems can be used for this purpose. The method to be used is determined by the required measurement frequency, the desire for threshold value alerts, the level of accuracy, duration, and costs.

Specifications

Automatic systems

  • Automatic measurement with Total station (tachymetry). Renders the absolute or relative x,y,z coordinates of the measuring point (suitable for buildings and railway construction, for example)
  • Automatic inclination measurement. Renders the absolute or relative horizontal deformation in relation to depth of the measurement tube, in direction a or b (suitable for construction pit walls and/or earthworks, for example)
  • Displacement sensors. Renders displacement in the measurement direction in time. These measurements can be executed with an extremely high accuracy of up to 0.001 mm (suitable for joints in tunnels, crack width in buildings, or in civil construction, for example)
  • Force and strain measurement. Renders the length change in the measurement direction of a structure in relation to its original length. These measurements are used to measure forces in structures (suitable for measuring strut or tie forces, for example)

Manual systems

  • Manual Total station measurement [tachymetry]. Renders the absolute or relative x,y,z coordinates of the measuring point.
    • This measurement is executed by a surveyor and will be repeated if necessary
    • Executing baseline measurements for buildings, structures or infrastructure
  • Manual inclination measurement. Renders the absolute or relative horizontal dislocation of a construction pit wall or measuring tube in relation to its depth
  • Engineering surveys. Strukton Survey & Monitoring assigns the pre-survey to a certified partner. You receive descriptions and photographs of defects in buildings and infrastructure in the vicinity of the construction site. These are documented accurately and recorded in a detailed pre-survey report
    • Baseline survey of the position
    • Crack width measurement
  • Laser scan of buildings, surroundings and/or infrastructure
    • Structures are scanned in high resolution (density depends on the structures to be scanned) and all geometric details are documented in relation to each other or in relation to a reference
    • The details can be developed into a digital model for 3D designs, modelling of construction stages, and in the case of recurrence

Applications

  • Settlement rods for monitoring vertical deformation of earthworks or banks. Can be performed manually or automatically (for example, for establishing the consolidation degree of pre-foundation of land
  • Automatic Total station for deformation measurements of buildings, civil engineering structures and railways (reference/link to chapter on railway deformation)
  • Slope or inclination measurement
    • Horizontal deformation or shifting of earthworks