Abstract
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.
Highlights
Tunnel engineering plays an important role in improving transportation networks
At distances greater than 10 m from the detonation site, numerous cracks were created throughout the secondary lining dominated by longitudinal cracks with local circumferential cracks. According to these damage traits, the lining can be divided into three zones characterized by complete failure, severe failure, and general failure. is paper performs a numerical investigation of the damaged section (ZK2 + 790∼ZK2 + 830) in the left hole of the tunnel, where the strength grade of the concrete used in the tunnel lining is 25 MPa
Where ΔPf is the peak overpressure of a blast shock wave, MPa; Z is the scaled distance, m·kg−1/3; R is the distance from the measurement points to the detonation, m; and W is the weight of the TNT explosive, kg
Summary
Tunnel engineering plays an important role in improving transportation networks. a security incident within the relatively confined space of a tunnel could lead to human casualties, substantial property and economic losses, and adverse social consequences. Hao et al [16,17,18,19] performed numerous numerical studies on the dynamic responses and damage mechanisms of concrete structures under explosions using the arbitrary Lagrangian–Eulerian (ALE) technique in LS-DYNA and compared the results with field experiments to demonstrate the feasibility of the method. Mussa et al [22] investigated the dynamic responses of buried rectangular tunnels under the explosions of different magnitudes of TNT and studied the damage degree and resistance of those tunnels to blast loading. The abovementioned studies are important references with respect to the research methods, constitutive models, and calculated parameters of the different materials involved in the numerical simulations Those studies provide quantitative data for the responses of structures subjected to blast loading. According to these damage traits, the lining can be divided into three zones characterized by complete failure, severe failure, and general failure. is paper performs a numerical investigation of the damaged section (ZK2 + 790∼ZK2 + 830) in the left hole of the tunnel, where the strength grade of the concrete used in the tunnel lining is 25 MPa
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