To address the significant challenges in plane layout under complex constraints for the Wuxi junction second-line ship lock,we summarize general layout principles of ship lock.Meanwhile,we fully consider influencing factors such as navigable flow conditions,geological compatibility,constructability,structural stability,flood control impacts,management area configuration,single-transit efficiency,land acquisition requirements,excavation volumes,and project costs.Adopting the method of combining quantitative and qualitative analysis,we select a reasonable general layout scheme through comprehensive comparative analysis.Based on this scheme,we conduct normal fixed-bed physical model tests and ship model tests to investigate the navigable flow conditions in the upstream approach channel of the second-line ship lock and their impacts on vessel navigation,using indicators such as maximum longitudinal/transverse flow velocities,maximum rudder angles,and minimum sailing speeds.We optimize the layout and structural type of the bulkhead through this experimental analysis.The results show that the scheme with the ship lock main structure located downstream of the anti-seepage cutoff wall is superior,as we find it reduces flood control pressures while ensuring construction convenience,better economic performance,and better structural stability.For the upstream bulkhead,we recommend the combination scheme of 100 m pile row (1.5 m center spacing) and 100 m pile inserted separation wall,which effectively addresses cofferdam challenges in the reservoir area during first-line ship lock navigation,and reduces project costs.The proposed layout scheme and methodology offer a valuable reference for the general arrangement of ship locks in similarly constrained reservoir areas,particularly those subject to multifaceted environmental and operational limitations.