Numerical and experimental analyses of methane leakage in shield tunnel

Abstract

Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases, such as methane gas. Based on the basic principles of computational fluid dynamics, a numerical analysis was performed to simulate the ventilation and diffusion of harmful gases in a shield tunnel, and the effect of ventilation airflow speed on the diffusion of harmful gases was evaluated. As the airflow speed increased from 1.8 to 5.4 m/s, the methane emission was diluted, and the methane accumulation was only observed in the area near the methane leakage channels. The influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four fans. In addition, laboratory tests on methane leakage through segment joints were performed. The results show that the leakage process can be divided into “rapid leakage” and “slight leakage”, depending on the leakage pressure and the state of joint deformation. Based on the numerical and experimental analysis results, a relationship between the safety level and the joint deformation is established, which can be used as guidelines for maintaining utility tunnels.

Graphical abstract

Keywords

shield tunnel / harmful gas leakage / numerical analysis / laboratory test

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Acknowledgements

We thank Mr Rui Jin (Tongji University) and Mr Yaji Jiao (Tongji University) for assistance in the research. This study was funded by the China Postdoctoral Science Foundation (No. 2019M651580) and the Research Project of the Chinese National Major Scientific Instrument and Equipment Development (No. 41827807). The authors gratefully acknowledge this support.

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Conflict of Interest

The authors declare that they have no conflict of interest.

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2023 The Author(s). This article is published with open access at link.springer.com and journal.hep.com.cn