The operation of the cone shell blocks of offshore structures under ice impact

Abstract

The prospects for the development of the Azov-Black sea region of the Russian Federation are primarily related to the development of the deep-water part of the Black Sea. In general, the forecast hydrocarbon resources are estimated at 1,5-2,4 trillion m3 in gas equivalent. Ice loads are one of the most important factors determining the stress state of the entire stationary platform when developing and designing offshore structures for the gas field in the Sea of Azov. The author of the article proposes to install special structures, such as cone icebreaking devices, at the contact points. An analytical study of the stress state of ice-breaking devices is carried out on the basis of the general provisions of the theory of elasticity of thin plates. An expression defining the strength condition of the cone shell material is obtained. The device of the Ansys17.2 software complex was used to obtaining specific results of calculations of the stress state of the ice-breaking device. Improving the platform support post by installing cone structures reinforced with concrete in the contact zone results in the destruction of the ice field from bending rather than compression. In this case, the horizontal pressure of the ice on the support is reduced. As a result, the stress level in the elements of the offshore structure support post is reduced. Due to the three-axis compression of concrete, the stress decreased in the model reinforced metal shell by 3,7 times compared to the level of stress in similar elements of the base model, and 1,7 times compared to the model with metal stiffeners. Deformations of elements in the direction of force ice action decreased from 4 cm in the base model to 1 cm in the rib-reinforced model of the ice-breaking device, i.e. by 4 times, and to 0,2 cm in the model reinforced with concrete, i.e. by 20 times. The use of composite construction leads to an increase in the rigidity and strength of the structure to protect offshore structure from the effects of ice.