Investigations on telescope yielding elements with porous filling

Tunnelling in weak ground and under high overburden always proves to be challenging during the design and construction phase. Currently, tunnels are constructed with great lengths, which increases the probability of crossing tectonic fault zones under high overburden. These geological conditions are commonly associated with high loads and massive deformation of the lining. The idea of using ductile elements in the lining has become a well-known practice in such conditions. During the last century, different solutions have been developed. In this paper, the focus is on Telescope-Yielding-Elements (TSR). The big advantage of these elements is that forceoscillation can be reduced to an insignificantly low level and the deformation behavior can be controlled by the use of porous fillings, different types of steel pipes and additional free space. We discuss the results and show the scope of application of such elements. In addition, we highlight how minor modifications of the element configuration can look like to suit Telescope-Yielding-Elements to specific project conditions.