Numerical Study On Reflectivity And Stability Of Perforated Caisson With Multiple Chambers Under Hydrodynamic Action

In recent years,offshore wind power and nuclear power have become a new direction of power development.China has a vast territorial sea area and a long coastline,which is very conducive to the development of offshore wind power and nuclear power.The development of offshore wind power and nuclear power resources is an important way to solve the problem of insufficient power supply in the southeast coastal power load center of China.To ensure the safety and reliability of offshore and cross sea power transmission facilities under the action of waves,it is necessary to use necessary anti wave structures.The perforated caisson is a new type of protective structure applied in offshore engineering,which can significantly reduce the reflected wave in front of the wall,the pressure of shock wave and the transfer wave caused by overtopping.The multi chambers perforated caisson is the expansion of single chamber perforated caisson.It has better effect in reducing reflected wave,shock wave pressure and wave transfer caused by overtopping.Multi chambers perforated caisson can be transported to offshore wind power,nuclear power,cross sea power transmission and other power facilities that need to have anti wave function.Numerical Research on the hydrodynamic performance of multi chambers perforated caisson in this paper can enrich the theoretical research on the hydrodynamic performance of multi chambers perforated caisson,and also provide reference for the design and construction of multi chambers perforated caisson.In this paper,the finite element method is used to study the interaction between waves and the perforated caisson with single chamber and the perforated caisson with two chambers.The VOF model is used to trace the surface of water flow and establish a numerical wave tank.In the numerical wave flume,the total reflection theory of the solid caisson is firstly verified,and the wave pressure theory is verified at the static water level,the half water level and the zero water level(the bottom of the flume).The calculation results are in good agreement with the theoretical solutions.Then,the simulation calculation of the perforated caisson with single chamber and the perforated caisson with two chambers is carried out,and the calculation results are compared with the two empirical formula values of the physical models.The calculated results of the reflectivity and the total horizontal force ratio are consistent with the empirical formula values of Chen Xuefeng.On this basis,the reflectivity and total horizontal force ratio of the perforated caisson with single and the perforated caisson with two chambers in full depth of water are simulated,and the results are compared with the reflectivity and the total horizontal force ratio of the perforated caisson with single and the perforated caisson with two chambers in half depth of water.It is concluded that when the water depth is relatively shallow,In the process of d1 increasing from d/2 to d,the reflectivity of the perforated caisson with single and the perforated caisson with two chambers decreases gradually,and the total pressure ratio increases gradually,the influence of the water depth in the chamber of the perforated caisson on the reflectance and the total pressure ratio must be considered.The numerical wave flume established in this paper can simulate the interaction between waves and the perforated caisson with single and the perforated caisson with two chambers,and it provides a way to study the hydrodynamic performance of perforated caisson.It is concluded that the influence of the water depth in the chamber of the perforated caisson on the reflectivity and the total pressure ratio must be considered when the water depth is shallow,which has certain reference value for the theoretical study of the opening caisson and the solution of practical engineering problems.