Response of submerged floating tunnel under action of underwater explosion-moving load

Abstract:

To investigate the deformation law of submerged floating tunnel (SFT) subjected to underwater explosion-moving load, the underwater explosion process was simplified to the stages of shock wave load and bubble motion based on the Cole shock wave load semi-empirical formula and Vernon bubble motion equation. The Grade I vehicle load of highway was simplified to the moving load sequence. A dynamic model of SFT considering underwater explosive load, moving load, and fluid effect was established based on the D’Alembert’s principle. The four order Runge-Kutta method was adopted to solve the differential equations of motions, and the proposed model was verified by using the existing data and formulas. Finally, the effects of explosive load and moving load on the deformation of the tunnel were discussed. Results show that the impact factor  could greatly promote the increase in the maximum displacement of SFT. Compared with =0.1, when the impact factor increased by 2 times and 4 times, the maximum displacement of the tunnel increased by 4 times and 10 times under explosive load alone. With the increase in the explosive amount, the bubble load frequency increased exponentially, with the increase in the water depth of the explosion point, the bubble load frequency decreased in inverse proportion. In the cases of different explosive amounts and water depths, the bubble load frequencies were all less than 3 Hz, which was close to the low-order frequency of the tunnel and easily led to resonance. Under the action of underwater explosion and moving load, the maximum displacement of SFT was affected by the combined effect of the position and speed of the moving load, and the explosion was more harmful to the tunnel when the vehicle ran at the fastest speed until the mid-span.