Transverse Mooring Forces Due to Asymmetrical Filling in a Lock with Longitudinal Culverts and Side Ports

Abstract

AbstractIn lock design, several geometries are proposed for the levelling system with the aim of insuring a smooth and fast levelling operation. For high and medium lift lock, longitudinal culverts with side ports located in the lock walls are often chosen because this system distribute the flow along the entire length of the lock chamber. Nevertheless, when one of the culvert (valve) is out of order, the flow is asymmetrical what induced significant transverse mooring forces, especially during filling operations.Field measurement on such a lock (225 m long, 25 m wide and 13.5 m lift) demonstrated transverse water slopes significantly larger than the admissible criteria during asymmetrical filling operation. Further investigations on a physical scale model highlighted the driving effect of the side port jets on the rolling flow. Detailed measurements were performed on the scale model covering: (1) water surface slope; (2) transverse velocity distribution; (3) transverse mooring forces and rolling angle of a vessel located in the lock chamber. It was concluded that the size of the outlets of the side ports has a major impact on the transverse forces. For smaller outlets at a given discharge, the flow velocity increases and more impulse is transferred to the rolling flow, resulting in larger forces on the vessel.