Short-term prediction of shotcrete utilization based on observations during tunnelling

Displacement curves in tunnelling depend both on time and the distance from the face and have thus not died down immediately after excavation. Therefore – the applied shotcrete lining experiences temporally variable loading, which depends on the forced strain curve and on the material behaviour of the shotcrete. Overloading of the shotcrete lining leads to crack formation, costly and laborious repair work and possibly also to dangerous situations for those present at the location, and should therefore be prevented. With the method presented in this article, which combines geological-geotechnical parameters and the interpretation of measured displacement data, the accuracy of the short-term prediction of the system behaviour can be improved. This makes it possible to react early to any potential overloading of the planned support and adapt it if necessary (e.g. changeover to ductile support). The article concludes with an explanation of the method through the example of the Semmering Base Tunnel, contract SBT 1.1 – Tunnel Gloggnitz.