Author: ARMY ENGINEER DIV NORTH PACIFIC BONNEVILLE OR DIV HYDRAULIC LAB.

Publisher:

Published: 1979

Total Pages: 110

ISBN-13:

The Lower Granite navigation lock is designed for maximum, average, and minimum lifts of 105, 100, and 87 ft, respectively. The filling and emptying systems are dynamically balanced hydraulic systems that include a unique arrangement of eight longitudinal floor culverts symmetrically placed around the center of the 86- by 675-ft lock chamber. Portions of the forebay and tailrace, two adjacent spillway bays, and elements of the lock chamber and hydraulic system were reproduced in a 1:25-scale model. Tests of the proposed system indicated that turbulence and longitudinal hawser forces on barge tows in the lock chamber were excessive with a 4.0-min valve schedule at the design head of 105 ft. Pressures on the culvert roofs downstream from the filling valves were satisfactory when both valves were operated. With one valve, the minimum instantaneous pressure was -19 ft of water. Revised ports and baffles along the walls and over the ports were developed to reduce turbulence in the lock. Average maximum hawser forces of 6.2 tons on an eight-barge, 9-ft-draft tow and 9.9 tons on a four-barge tow in the original design lock were reduced to 1.4 and 1.7 tons, respectively, in the final design. A filling time of 9.8 min was obtained with a 1.11-min valve period and still maintained acceptable flow conditions, pressures, and hawser forces.