Abstract: The inverse T type breakwater with jackets and pile foundations is a new type of structure applied to port and coastal engineering, of which the stability is sustained by pile foundations and gravity. In terms of the hydrogeological conditions of Tianjin Port, a 3D elastoplastic finite element model is estabilished for stability analysis of the inverse T type breakwater with jackets and pile foundations. The safety factor of stability is determined by P-S curve. The soil resistance is calculated by analyzing the vertical and circumferential distributions of earth pressure on pile foundations in the limit state. Besides, the earth resistance calculated by the finite element method is compared with API. There are two main reasons which cause structural instability: Firstly, the structure itself is unable to meet strength requirement; Secondly, the soil is in the limit of state. For the first reason, calculate the safety factor of stability by p-y curve method. When the soil is in the limit state, simplified methods for anti-overturning stability based on the rotation point which is on the pile axis or deviates from the pile are set up. In comparison to finite element method, simplified calculation method is reliable.

Key words: inverse T type breakwater with jackets and pile foundations, finite elements, earth pressure, p-y curves, stability, simplified calculation methods