Tunnelling Industry

Within the current range of the tunnel construction types work is not only required underground!

Quality inspection and safety are essential for tunnel constructions, also with segments they are of enormous importance. The following measuring tasks are particularly typical for the use of industrial measuring systems in the tunnel construction:

• Measurement of large structural steel constructions and steel segments
• Survey of concrete segments, their gauges and moulds
• Measurement of circularity

The VMT GmbH has different measuring systems in the employment for such varying tasks. It comprises optical precision instruments, which determine 3-D coordinates on the basis of angle and distance measurements (laser tracker, theodolite measuring system) as well as using digital pictures (digital photogrammetry system) of high precision. Common to all systems are their large mobility, their high reliability and their extensive accessories for covering of all demanded tasks.

Primary control

Precise geometry control of a gauge and moulds by means of 3D measurements, take at them, before the first segment is produced. Exactly the same way as the measurement of the first casting, is indispensably for the examination of each set of moulds. The direct comparison of results of individual moulds and their segments casted from them, makes an uncovering of construction deviations in the sub-millimetre range possible. Primary control will be accomplished completely independently, in the course of regular production.

They are comprising not only the examination of geometry properties, but also the examination of gasket grooves, pins and other attachments. Whereby it has to be made sure that moulds and segments are measured under the same environmental conditions. As results one receives first the 3D-Object coordinates along with their standard deviations in the format "point name X Y Z dx dy dz". ´

The computation of standard geometry, the comparison with the designed construction values and all relevant tolerances will be accomplished just after coordinate acquisition under the use of "TubGeo".

• Software for the computation of standard geometry at reinforced concrete segments, gauges and moulds for tunnel construction projects
• Individual adjustment at target being fixed at reinforced concrete segments, gauges and moulds for tunnel construction projects
• VisualBasic scripts for the controlling of regular measurements
• Interactive guidance the entire measurements
• Individual programming of repetitive tasks of the user during the entire measurements

Secondary control

By secondary control one understands the regular examination of complete rings (each segment type of a set of moulds) and the appropriate moulds themselves. Typical cycle times of measurements are e.g. a ring per week or each twentieth segment out of a specific mould. The object which shall be examined (mould or segment) is taken out of current production and made available somewhere at a suitable measuring location in the production hall.

With secondary control the six enclosing surfaces and the distances and angle derived from it are determined. The data acquisition runs semi-automatically under a few menu functions with help of the program "TUBGEO". The crucial results developed by VMT in a metrology record (graphic or text-based) are as follows, they are containing the measurements, the deviations and clear statements concerning adherence to the tolerances.