Selection of supply systems for medium-head navigation locks

Conclusions

• 1. In the design of lock chamber walls, use of the criterion for standard openings of cracks reduces the volume of work and enables the strength properties of reinforced concrete to be utilized rationally.

• 2. Navigation locks with a distributary supply system, having a large discharge capacity and better conditions for detention of vessels, when constructed on compact foundations (siltstones, clays) do not increase the volume of construction compared with locks having the headwork type of supply system.

• 3. Locks with a headwater supply system (undershot gate flow) at heads exceeding 10 m are characterized by a strongly pronounced aeration of the flow, which renders more difficult the vessel detention conditions during chamber filling and cannot be modeled in laboratory studies. Operating experience show that service conditions in them in the filling regimes prescribed in the design are often not satisfactory, particularly in locking-through hightonnage trains of barges. This makes it reasonable to consider that, for heads over 10 m, distributary supply systems are to be preferred.

• 4. Locks with heads of 5–10 m and a headwater supply system should have a submerged filling-stage regime which does not permit entrainment of air into the flow.