Aiming at the complex hydraulic issues arising from shared approach channels of double-line ship locks with significant scale differences under space-constrained conditions,we conduct a systematic study using a comprehensive physical model with a geometric scale of 130,on the basis of the double-line ship lock project of the Jiantan navigation hub.The results show that the ship lock chamber width has the controlling role on ship mooring conditions,revealing that narrow ship lock chambers experience intense jet impact during unilateral filling,leading to transverse mooring forces prone to exceeding code limits,whereas wide lock chambers provide ample space for water flow diffusion.The flow superposition effect during simultaneous filling and emptying of the double-line ship lock,which significantly influences the flow conditions in the mooring sections of both upstream and downstream approach channels.By implementing an optimized measure that staggered scheduling is not shorter than the valve opening time,water level fluctuations in the mooring sections of the upstream and downstream approach channels can be effectively controlled within 20 cm,while mooring forces also comply with code requirements.