The inland navigation system,composed of series arrangement of ship lock,ship lift,and the intermediate channel connecting them,features a complex structure and limited anchorage capacity for navigation buffering.This makes it vulnerable to unexpected disruptions and poses significant challenges to restoring stable operation.Taking the configuration of series arrangement of ship lock and ship lift as the research object,we propose using the value of t1/(Qt2) as a quantitative robustness indicator,where t1 is the recovery duration,Q is the freight volume,and t2 is the number of failure days.By developing a simulation model of ship lockage operations under coordinated functioning of these structures,we quantitatively analyze the robustness of navigation system under various scenarios of freight volume and failure duration.The results indicate that when the passage capacity of the navigation system substantially exceeds the freight volume,increases of freight volume or failure days have a relatively mild effect on robustness.However,when freight volume approaches the system’s passage capacity,the effect of failure days on robustness becomes significantly more pronounced.The findings provide references for robustness research in multi-structure navigation systems,quantifying the impact of short-term disruptions such as facility failures and analyzing navigation reliability.