On the optimum design of reinforcement systems for old masonry railway tunnels

Safety is a most important parameters in underground railway transportation; Also stability of underground tunnel is very important in tunneling engineering. Design of a reliable support system requires an evaluation of both ground demand and support capacity. Iran's traditional railway tunnels are mainly supported with masonry structures or unsupported in high quality rock masses. A decrease in rock mass quality due to changes in groundwater regime creep and fatigue in rock and similar phenomena causes tunnel safety to decrease during time. The case study is an old tunnel in Iran, called Keshvar; it is more than 50 years old railway organization. In operating this Tunnel, until the several problems came up based on stability and leaking water. The goal of study is evaluation of the various reinforcement systems for supporting of the tunnel. The optimal selection of the reinforcement system is examined using TOPSIS Fuzzy method in light of the looming and available uncertainties. Several factors such as; the tunnel span, maintenance, drainage, sealing, ventilation, cost and safety were based to choose the method and system of designing. Therefore, by identifying these parameters, an optimal reinforcement system was selected and introduced. Based on optimization system for analysis, it is revealed that the systematic rock bolts and shotcrete protection had a most appropriate result for these kind of tunnel in Iran.

Automated summary

Safety is of utmost importance in underground railway transportation, and the stability of underground tunnels is crucial in tunneling engineering. Traditional railway tunnels in Iran are primarily supported by masonry structures or left unsupported in high quality rock masses. This study evaluates different reinforcement systems for supporting a 50-year-old tunnel in Iran named Keshvar. Through an optimization analysis, a systemic rock bolts and shotcrete protection method is found to be the most suitable for this type of tunnel in Iran.