Study on the protection mechanism and damage grade prediction of different corrugated steel‒concrete composite structures under underwater contact explosion

Abstract

Considering that corrugated steel has a certain anti-explosion protective effect, the influences of corrugated steel shape parameters on the protective effect of corrugated steel–concrete composite structures have not been considered. In this paper, the FEM–SPH coupling method is used to establish a simulation model of an underwater contact explosion wall panel. The numerical results are compared with the experimental results to verify the effectiveness of the simulation method. Furthermore, the underwater energy absorption effect, protection effect and influences of the wall panel of different composite structure protective layers on the damage process and failure mode are explored, the underwater explosion-proof mechanism is revealed, and the prediction curve of the damage grade of the wall panel is constructed. The results show that simulation results of the concrete slab front and back explosion surfaces are basically consistent with the experimental results. Under different composite structure protection schemes, the peak pressures of the composite structure protection schemes with 12-mm-thick corrugated steel and with 75° corrugated steel are reduce by 63.2% and 60%, respectively, relative to the noncomposite protection scheme, while the total energies of the corresponding composite structure are increased by 50.6% and 61.4%, respectively; the damage ranges of the wall panel are reduced by 83% and 81.6%, respectively. This finding shows that changing the corrugated steel shape parameters in the composite structure can effectively improve the energy absorption effect and reduce damage to the wall panel. The blast wave first propagates to the corrugated steel in the form of an incident wave and then propagates in the form of transmitted and reflected waves. Part of the wave propagates to the wall panel when the transmitted wave arrives at the corrugated steel lower surface, while the rest of the wave forms a reflected longitudinal wave and reflected transverse wave through reflection. Then, the transmitted wave acting on the wall panel attenuates. Under the protection schemes of the corrugated steel composite structure with a 12-mm thickness and corrugated steel composite structure with a 75° angle, the maximum protection rates are 63.2% and 60.0%, respectively, the energy consumption sharing rates are 69.48% and 66.26%, respectively, and the damage levels are moderate. The multiangle comparative analyses of different protection schemes suggest that the corrugated steel composite structure with a 12-mm thickness should be selected. The prediction curve can intuitively evaluate the influences of the quantity of explosive loads and the thickness/angle of corrugated steel changes of the composite structure on the damage to the wall panel. The research results can serve as a reference for the adhibition of underwater explosion protective engineering projects.