Convergence meter with reflector

For the convergence measurement of, for example, tunnel sections, use can be made of special bolts with reflectors. The bolts are installed so that it is possible for the reflector to be measured in with the aid, for instance, of a theodolite. By repeated measurements, the deformations in the rock mass can be evaluated. The bolts are also supplemented for use in manual convergence measurement with tape extensometers if the demands for accuracy are particularly high.