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http://dx.doi.org/10.9711/KTAJ.2020.22.4.451

A numerical study on the behavior of existing and enlarged tunnels when widened by applying the pre-cutting method  

Kim, Han-Eol (Dept. of Civil and Environmental Engineering, Hanyang University)
Nam, Kyoung-Min (Dept. of Civil and Environmental Engineering, Hanyang University)
Ha, Sang-Gui (Dept. of Civil and Environmental Engineering, Hanyang University)
Yoo, Han-Kyu (Dept. of Civil and Environmental Engineering, Hanyang University)
Publication Information
Journal of Korean Tunnelling and Underground Space Association / v.22, no.4, 2020 , pp. 451-468 More about this Journal
Abstract
Aging tunnels with small cross-sections can cause chronic traffic jams. This problem can be solved by widening the tunnel. In general, when the tunnel is expanded, the outer portion of the existing tunnel is excavated through a mechanical or blasting method. Such excavation affects not only the surrounding ground but also the existing tunnel. The application of the pre-cutting method can be a solution to these problems effectively. Therefore, if the widening of tunnel is performed by applying pre-cutting method, analysis of the impact of this method must be performed. In this study, in order to analyze the effect of applying pre-cutting in tunnel widening, numerical analysis is performed at six ground grades, from grade I to weathered rock. The analysis is performed with the expanding lane and the excavation length of pre-cutting as variables. In addition, the analysis is focused on the displacement of crown of the existing tunnel and the enlarged tunnel. As a result, the crown displacement of the enlarged tunnel is confirmed to converge at the same value regardless of the excavation length of the pre-cutting when the tunnel widening is completed. In the case of existing tunnels, uplift of crown occurs within 5 m of the front of the tunnel surface, and the shorter the excavation length of pre-cutting is found to be effective in preventing the occurrence of uplift.
Keywords
Tunnel enlargement; Pre-cutting method; Crown settlement; Enlarged tunnel; Existing tunnel;
Citations & Related Records
Times Cited By KSCI : 10  (Citation Analysis)
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