Stability Analysis Of A Breakwater Under Wave Loading At Yantai Port:An Application Of FSSI-CAS 2D

In the marine environment,seabed foundations are softened or even liquefied under the cyclical loading of waves,which in turn leads to instability of buildings such as breakwaters above foundations.Taking the national key project—the second phase of the breakwater of Yantai Port Xigang District in Shandong Province as the background,the safety and stability of the breakwater was evaluated.There are strong non-linear interactions between waves,seabed foundations,and ocean structures.The three interact with each other and it is an organic whole.The traditional design specification method only checked the static bearing capacity of the seabed foundation and could not consider the dynamic response of the seabed foundation under cyclic dynamic loading.The results obtained from indoor tests are of good reliability;however,the cost of conducting tests is very high.The mathematical calculation model not only has low cost,but also can consider the influence of the seabed topography on the waves,and the calculation of the wave force is more accurate;at the same time,the mathematical calculation model can also use the elastic-plastic constitutive model of the soil to describe the seabed foundation under the dynamic load of the wave.The deformation and dynamic bearing capacity change process.The elasto-plastic constitutive model PZIII is used to describe the mechanical behavior of the seabed soil.The numerical coupling model FSSI-CAS 2D is used as a tool to calculate the dynamic response of Yantai Port breakwaters in the 50-year extreme wave conditions,from deformation and liquefaction.Angle to evaluate the safety and stability of the breakwater.According to the geological survey data,the geometrical size of the calculation model of the breakwater and the seabed stratum is determined;the parameters of the PZIII constitutive model are obtained through parameter estimation;and the hydrodynamic parameters are set with the actual observation of the hydrology and wave conditions in the West Port of Yantai Port.The numerical simulation model FSSICAS 2D was used to calculate the hydrodynamic distribution of the breakwater of Yantai Port under extreme wind and wave conditions,the displacement of the breakwater,horizontal thrust and overturning moment,the deformation of the seabed,stress distribution,and the dynamic change process of pore pressure.Based on the dynamic response of effective stress and pore pressure,the distribution of seabed liquefaction zone was judged.The results of the study showed that the breakwater in Yantai Port West Port has a strong ability to withstand the over-flow of seawater under extreme waves,which has a good protective effect on the facilities within the harbor.The breakwater has sufficient resistance to bending moments and there is no risk of overturning under extreme wave impact.Some of the submarine foundations may be liquefied,and at the same time,the vertical settlement and horizontal displacement of the breakwaters in the high-stress area of the seabed foundation below the breakwater are small.Therefore,the safety and stability of the composite breakwater of Yantai Port West Harbour Area during the service period can be guaranteed.The study applied the numerical calculation model FSSI-CAS 2D for the first time to a complex practical engineering case.Quantitatively evaluate the safety and stability of offshore structures and provide a theoretical basis for the design of marine structures and maintenance within their service life.