RESEARCH ON THE NAVIGATIONAL CONDITION IN THE DIVERSION CHANNEL OF TGP BY MODEL SHIP TESTS AND PROTOTYPE VERIFICATION

摘要

The diversion channel is being used as a navigational pass during the second construction phase of the Three Gorges Project (TGP). By means of model ship and hydraulics tests, the essential problems on the sailing line optimization, the methods of enhancing navigable discharges, protection measures of anti-scouring during flood period and scouring effects on navigation, etc., have been appropriately solved. The important main data for design and construction were provided based on the experimental results which have been well verified by prototype barges-tow tests and the navigational practices during1997 -1998. The test results obtained from physical model and prototype indicated that the maximum navigable discharge in the diversion channel is restricted by up-bound passage. If excessive navigable discharge is required, quickening the vessel speed with special methods is an effective way. The navigational practices reveal that the model ship test results can correctly reflect the prototype situation, including the effect of the flowing water on vessels and the maneuver characteristics of the vessel. Therefore, model ship test is a effective method in the researches of sailing line optimization, navigable discharge enhancement, scouring effect on navigational condition, etc.. The model test results revealed that some regions in the diversion channel would be scoured due to the high flowing water velocity and the navigational condition would be affected. Therefore, some protection measures were conducted in prototype. The prototype investigation results indicate that the protection measures are effective. The navigational condition in the diversion channel after the flood reason in 1998 does not varied with the only exception of a special section in the channel downstream of the dam where the channel was scoured a bit, and the navigation difficulty in this section rises a little. The anti-scouring protection of this section should be strengthened.