Load capacity of inner lining system s due to impact from falling rocks
2015 (English)In: SEE Tunnel: Promoting Tunneling in SEE Region / [ed] Davorin Kolic, Dubrovnik, 2015Conference paper (Other academic)
The inner lining concept is a method to prevent water leakage and the risk of icing inside tunnels and is frequently used in countries with cold climate. Blocks of falling ice may result is a severe safety risk in both road and railway tunnels. Although several established inner lining systems exist, finding the optimal solution considering function, maintenance- and investment cost is a challenging task. A new system has recently been used in Sweden and is due to its success planned to be used for the Stockholm Bypass, an 18 km road tunnel project in Stockholm.
A set of design criterions has been stipulated for the inner lining system. In this paper, the case of impact loading from falling rocks is studied. The inner lining system is required to withstand the impact of a 600 kg block landing on a square surface of 0.2x0.2 m. The free fall height, i.e. the distance to the rock surface, is typically less than 0.5 m but may span up to 1.5 m in some cases. A too conservative design may result in an unnecessary thick structure and lack of knowledge of the impact phenomena may result in an unsafe design.
An extensive experimental program has been performed, consisting of representative parts of the inner lining system. A mass of 600 kg is dropped onto the structure and the results are compared with numerical simulations. The experiments show that the current system is rather ductile but that local concrete fallouts may occur at extreme free fall heights.
Place, publisher, year, edition, pages
Inner lining system; shotcrete; impact load; experimental testing; FEM
Research subject Civil and Architectural Engineering
IdentifiersURN: urn:nbn:se:kth:diva-168297OAI: oai:DiVA.org:kth-168297DiVA: diva2:815538
ITA WTC 2015, 41st General Assembly and World Tunnel Congress of International Tunneling and Underground Space Accociation ITA-AITES,May 22-28, 2015, Lacroma Valamar Congress Center, Dubrovnik, Croatia
QC 201506172015-06-012015-06-012015-06-17Bibliographically approved