NATM support in Prague's weak rock

摘要

It is very important when excavating large diameter NATM tunnels in an urban area, to determine spatial characteristics and the magnitude of ground movements. In particular surface settlement may cause serious harm to third party structures. Keeping the tunnel induced deformations of the ground within acceptable limits is one of the main objectives of all participants in the tunnel construction works. Numerical modelling, when calibrated with monitoring data from the construction site, is a useful tool in assessing the influence of various support measures in the tunnel. The presented back analysis of the support measures for the Mrazovka tunnel illustrates this.