Numerical Investigation of the Dynamic Responses and Damage of Linings Subjected to Violent Gas Explosions inside Highway Tunnels

The linings of structures suffer severe damage when subjected to internal explosions, which cause numerous casualties and incalculable economic losses. In this paper, a violent gas explosion that occurred inside a highway tunnel in the city of Chengdu, China, is studied through numerical simulations. The evaluated energy of the gas explosion was equivalent to 2428.9 kg of TNT. A fully coupled numerical model consisting of five parts is established with dimensions consistent with the real prototype dimensions and by considering fluid-structure interaction (FSI) effects. Then, a detailed modelling process is presented and validated through a comparison with empirical formulas. This paper investigates the strength and propagation characteristics of a blast shock wave inside the tunnel, and both the effective stresses and dynamic responses of the lining are analysed under the blast impact loading. The damage mechanism is studied, and the evolution of the lining damage is reproduced, the results of which show good agreement with the actual conditions. Moreover, in terms of the responses and damage of the lining, the fully coupled blast loading model has obvious advantages in comparison with the simplified blast loading model. Furthermore, the damage assessment of the lining conducted using the single degree of freedom (SDOF) method agrees well with the results of the numerical simulation and site investigations. The comprehensive numerical simulation technique used in the present paper and its results could represent valuable references for future research on violent explosions within tunnels or very large underground structures and provide relevant information for the blast-resistant design of such structures