Along many segmental lined tunnel projects the client often defines specific locations where deformation measurements have to be performed by the contractor.
The most important considerations to the initial deformation of a ring that has just been built are the pressure of the jacks during next advance and subsequent load changes, e.g. the passing of the shield’s tail, primary and secondary grouting, passing of the last back-up trailer and any potential long term effects.
VMT’s RCMS system is based on the use of a series of inclinometers on the ring to be observed. One inclinometer is installed in every ring segment to be measured. “Deformations can only take place along the longitudinal joints, which are treated as articulations. Any movements of the rigid segments have as primary components some changes of their vertical inclinations, which can be observed by inclinometers,” the company explains.
The Ring Convergence Measurement System, for evaluation of the changes in shape of the ring within the confines of the back up equipment, where conventional surveying is problematic, is now in use on several projects in Europe.
VMT
Tel: +49 7251 96 99 0
Email: international@vmt-gmbh.de
Web: www.vmt-gmbh.de
VMT’s RCMS system
