ABSTRACT
Probabilistic methods can provide more insight on risk allocation and can be used in Geotechnical Baseline Reports (GBR). A novel, probabilistic approach of the spatial distribution of karstic cavities is presented to assess the risk of liner instabilities when tunnelling through karstic limestone. The presented research work is based on the following geotechnical baseline statement: “There is a 10% chance of encountering a sediment-filled cavity, with a maximum size of 2m3”, which was assumed to be correct for the analysis. A Matlab script generates a random distribution of karst cavities, modelled as a circular shape, which is transferred into FEM 2D and 3D numerical analysis. The measured variable is the index for capacity utilization of linings in tunnels (CULT-I), which act as proxy for liner stability assessment. The methodology presented provides a framework for further investigations to assess the risk from karst cavities to tunnelling works.
