Use of convergence-confinement method for preliminary support design in tunnelling

摘要

The main aim of the presented thesis is an analitical analysis of the primary support system in the tunnels, constructed according to the priciples of the New Austrian Tunneling Method (NATM) using convergence-confinement method. To determine a ground reaction curve of the surrounding rock mass, parameters were calculated using Geological Strenght Index (GSI). Further on different types of support and their contribution to the support curve are discussed. Support curve shape depends on the type of support used, time of support installation and approach to the support consideration. Shotcrete and steel arches are always incorporated in the support curve while rockbolts can be included as part of the support curve or in the convergence curve due to rock reinforcement effect. Both approaches are presented and implemented into the Excel spreadsheets allowing their comparison. To verify both approaches, the measured displacements from some tunnels on the Slovenian motorway network were compared to the calucalted values as presented in the Appendix to the thesis.