Experimental investigations on the influence of embedment depth and frequency on the dynamic behaviour of tunnels under repeated shaking events

ABSTRACT

Recently, occurrence of repeated shaking events such as the Kobe earthquake (1995), the Wenchuan earthquake (2008), the Chi-Chi earthquake (1999) and the Kumamoto earthquake (2016), Kahramanmaras earthquake (2023), etc., posed a severe threat to the safety of infrastructures. Studies on the influence of repeated shaking events on underground structures are minimal. Considering the above, tunnel-soil interaction under repeated shaking events is attempted in the study. One-gram shaking table tests were conducted in this study by varying loading frequency (5 Hz, 10 Hz) and tunnel embedment depth (H/W − 0.85 and 1.2 where H is the tunnel embedment depth and W is the width of the tunnel) and subjected to incremental shaking conditions, i.e. 0.2 g, 0.3 g and 0.4 g. A tunnel-embedded ground with 60% relative density was prepared and instrumented with conventional sensor schemes and a non-contact-based 2D digital image correlation technique. It was observed that the loading frequency and tunnel embedment influences tunnel’s performance during repeated shaking events. About 37% to 62.4% increment in tunnel displacement was observed in the case of H/W-0.85, and 20% to 29% increment in tunnel displacement was observed for H/W-1.2 when subjected to incremental acceleration shaking, i.e. 0.2 g to 0.4 g for varying embedment depth conditions.

KEYWORDS:

• Tunnel-soil interaction
• influence of embedment depth of tunnel
• uni-axial shaking table tests
• conventional monitoring
• digital image correlation (DIC)

Acknowledgments

The authors would like to thank the Director, CSIR-Central Building Research Institute, Roorkee, for giving permission to publish this research work. The authors would also like to thank the Head, Geotechnical Engineering Division, CSIR-CBRI for his continuous support during this research work.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Author contributions

Both the authors contributed to the study conception. Material preparation, data collection and analysis were performed by Amith K.S. The first draft of the manuscript was written by Amith K.S., then reviewed by Ganesh Kumar Shanmugam and commented. Both the authors have read and approved the final manuscript.

Data availability statement

Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.