Abstract: Ground freezing method construction in coastal areas is significantly hindered by the combined effects of groundwater seepage and high salinity, which destabilize the morphological development of frozen walls, prolong freezing durations, and compromise construction quality. A systematic investigation into the evolution mechanisms of frozen wall morphology under coupled seepage-salinity conditions, along with corresponding optimization strategies, is urgently required. This study takes the Fuzhou Metro project as an engineering case, establishing a coupled hydro-salinity model integrating seepage flow and salt migration. The spatiotemporal evolution of temperature fields within the freezing zone is analyzed to determine the critical closure time of the frozen wall and its weakest section. A non-uniform freezing pipe layout methodology, based on the heterogeneous temperature development characteristics of the frozen front, is proposed. Results demonstrate that the synergistic influence of seepage velocity and salinity concentration significantly delays the closure time of the frozen wall. The most vulnerable section is primarily located on the upstream side of the frozen wall. With increasing seepage velocity and salinity, the growth rate of the upstream side's frozen wall thickness exhibits a marked decline. To address this, an asymmetric dynamic pipe layout scheme is proposed: densifying the layout of freezing pipes on the upstream side while advancing their installation positions, coupled with widened spacing and lateral displacement from the reference axis on the downstream side. This approach compensates for the heterogeneous development caused by seepage and salinity effects, as well as the freezing point depression mechanism, ensuring balanced advancement of the upstream and downstream frozen fronts and shortening the overall closure time of the frozen wall.