Model Test And Numerical Simulation Study On Bending Failure Process Of Level Ice

Marine structures in ice region are usually adopt special shape design to make level ice bending failure before the structure to reduce the ice load.The research on the bending failure process of level ice is helpful to reveal the failure law of level ice when interacting with structures,and then guide the anti-ice design of structures.According to the different direction of loading,the bending failure of level ice can be divided into downward bending failure and upward bending failure.In this paper,the two typical bending failure modes were studied by model test and numerical simulation.In terms of the numerical simulation for bending failure of level ice,a discrete element numerical model was established to simulate the failure of sea ice.The spherical elements in the model were randomly arranged,which can simulate the transversely isotropic properties of level ice at the structure scale.A modeling method was established that used to calibrate the mesoscopic parameters of discrete element based on the mechanical properties of sea ice,and realized the full coverage of discrete element simulation for model ice and natural sea ice.In terms of the model test for bending failure of level ice,the frozen salt water model ice was prepared which bending strength was 49.4k Pa,firstly.Based on the ice-breaking model test of the bow of “Xuelong 2” icebreaker,the downward bending failure mode of level ice was studied,and the influence of model ice thickness and ship velocity on the failure process of level ice and the ice force of the bow model were analyzed.Based on the ice-breaking model test of spherical surface ascending,the upward bending failure mode of level ice was studied,and the influence of the curvature of spherical surface,ice thickness and ascending velocity on the failure process of level ice and ice force on the spherical surface was analyzed.In the two bending failure modes,when the ice thickness is large,the extensional range of the bending fracture of level ice and the model’s force is large,while the influence of velocity is different in different bending failure modes.In the upward bending failure mode,when the curvature of spherical surface is large,the extensional range of bending fracture of level ice is large,while the change of ice force is opposite.Finally,the continuous ice-breaking process of “Xuelong 2” icebreaker during real scale and the ice-breaking process of spherical surface ascending were simulated by discrete element method.The simulation results of hull breaking ice show that the extensional range of bending fracture of level ice,average rubble size and ice-breaking resistance increase with the increase of ice thickness.The extensional range of bending fracture decreases with the increase of speed.The simulation results of spherical surface ascending and breaking ice show that the level ice in the simulation tends to be elastic-brittle,and the extensional range of bending fracture is smaller than that in the model test.The degree of ice fragmentation increases with the increase of the curvature of the spherical surface and ascending velocity.The discrete element method can accurately predict the ice load in prototype working condition.