Abstract: Taking the design of the boundary water interchange sluice for a land reclamation project in the coastal areas of Tianjin as an example,the double-layer sluices and single-layer sluices are calculated and compared in terms of flow capacity,structural internal force and investment. The results show that the use of a double-layer sluice chamber can solve the problem of sediment deposition in front of the sluice to a certain extent,without reducing the flow rate. On the contrary,it can slightly increase the flow rate. It can improve the stress condition of the box culvert,reduce the reinforcement of the box culvert,strengthen the lateral stiffness of the box culvert in the vertical flow direction,and reduce the uneven settlement of the foundation and the structural deformation of the sluice chamber. The increase of cost has little effect on the total investment of the project. Double-layer sluices have certain advantages in coastal areas or other easily silted rivers and soft soil foundations,which can provide reference for similar projects.

Key words: double-layer sluice, flow capacity, structural calculation, coastal areas