Old River Low-Sill Control Structure. Report 1: Downpull Forces on Vertical-Lift Gates: Hydraulic Model Investigation
Abstract
Flow through Old River low-sill control structure will be regulated in eleven 44-ft-wide gate bays. The sill for the three center bays will be at elevation -5 ft msl while the sill for the other eight bays will be at elevation 10ft msl. Flow will be controlled by multiple-leaf, . vertical-lift gates, providing a damming height to elevation 67 ft msl. Each gate in the side bays will consist of three 19-ft-high leaves, while each of the three center bays will require three 19-ft-high leaves plus a 15-ft-high leaf. Model tests were made to determine the vertical forces to which the gate leaves will be subjected by the extreme range of headwater and tailwater elevations that may occur at the structure. A 1:36-scale model of the low-sill structure was tested first and showed that both the 15- and 19-ft gate leaves would bounce violently under normal operating conditions, producing such destructive forces in the suspension system that the elimination of the conditions causing the bouncing assumed primary importance. A 1:60-scale model of one gate leaf was then installed in a glass-sided flume so that flow patterns around the leaf could be observed. These observations established that the bouncing was being caused by periodically fluctuating pressures as evidenced by the alternate formation of vortices off the top and bottom lips of the leaf. Operation of the lower two leaves in each gate bay fastened together and relocation of the air vents eliminated the bouncing. However, the necessity of operating two gate leaves fastened together imposed considerably increased loading on the hoisting apparatus since each leaf will weigh about 80,000 or 90,000 lb. The maximum applied downpull was found to be about 190,000 lb, which, when added to the dry weight of the two gate leaves, would result in a total hoist load of about 370,000 lb.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1956
- Accession Number
- ADA637658