MORE FUN THAN LINCOLN LOGS BUILD-IT-YOURSELF STOPLOG SYSTEM

摘要

Buchanan Dam was constructed more than 70 years ago. There were no provisions for gate dewatering systems in the original design. The Lower Colorado River Authority (LCRA) is the owner of the dam and is engaged in a dam modernization program to bring all of their dams into compliance with modern dam safety standards. Buchanan Dam is located on the Colorado River near Burnet, Texas, and has 37 tainter gates that need to be strengthened to meet current criteria. In order to perform the gate work, LCRA commissioned the design and construction of dewatering systems for all three Buchanan spillways. Several studies were performed on potential gate dewatering systems for Buchanan over a period of years. When LCRA requested that the selected gate dewatering system be capable of deployment in flowing water conditions, i.e. emergency conditions, Freese and Nichols, Inc. (FNI) recommended a stacked system of sealed Hollow Structural Sections (HSS) tubes pinned together as a unit. Hydraulic model studies were performed to prove the viability of the system. The system was shown to perform satisfactorily in all conditions, including emergencies. LCRA developed a plan to perform as much of the work as possible with LCRA staff. FNI provided engineering drawings for the required pier modifications, guide tracks, stoplogs, deployment system, and traveling overhead hoist. LCRA fabricated the stoplogs and the deployment system frame at their fabrication facility in Smithville, Texas. Several structural modifications were required on the small spillways to accommodate the new gate dewatering system. The concrete pier noses had to be reshaped to provide a sealing surface for the stoplog seals, and the concrete walkway adjacent to the hoists had to be removed to provide an access opening for lowering the stoplogs in each bay. There is a continuous monorail superstructure with HSS frames at each pier to accommodate the transport, storage and stacking of the stoplog system. The system is nearing completion on the first spillway. This paper will present the design, fabrication, and erection story of a project which features the owner as a very active participant in the hands-on construction.