Guiping navigation junction is a key project of the Golden Waterway of Xijiang River in Guangxi Province, South China. A 3rd Class navigation lock for the 1000t barge has been construction in 1989. Due to the rapid growth in waterborne economic these 20 years, the constructed lock can not satisfy the developing needs, so the 2nd lane lock has been constructed during 2007 to 2011. The new lock locates in the right side of the 1st lane lock, and the designed annual single direction traffic capacity is 31 million tons, which is 62% of the Three Gorges Locks. The effective lock chamber dimensions are 280.0m×34.0m×5.6m (length × width × water depth over the sill), which is same as the Three Gorges Locks, and that means the new lock is one of the largest inland navigation locks. The maximum water head of the lock is 10.5m, designed transit time is 8～10min, and the designed vessels are 3000t barge and 2×2000t pusher train.
The initial type of the filling and emptying system for Guiping 2nd lane lock is the side ports system, but during the detailed design phase, the geological exploration results indicate that the geological conditions of the lock site are quite well, the lock wall can adopt the lining type. So a in-chamber single longitudinal culvert with shallow open ditch filling and emptying system and its layout has been put forward, which have high hydraulic performance and do not need set the main culvert in the lock wall, also have smaller bottom excavation. The physical model tests show that, the adjustment of the lateral flow distribution is the key problem of this new filing and emptying system. Considering the large space in the chamber width, a new energy dissipating device — double open ditches has been invented to replace the former single open ditch. The layouts of the open ditches and the baffle wall between the two open ditches have been optimized on the basis of series model tests. The tests results indicate that the new energy dissipating device effectively improved the flow conditions and the berthing conditions in lock chamber, and obviously decreased the project cost at the same time.
After the 2nd lane lock has been completely constructed and before its formal open for navigation, the prototype observation and debugging has been carried out to know the actual operation conditions and the differences between prototype and model. According to the detailed analysis of the actual hydraulic characteristics, flow conditions and berthing conditions, a conclusion has been made that the new filling and emptying system guaranteed the lock’s efficient operation, and greatly improved the flow conditions in lock chamber at the same time, which becomes a safe and rapid channel passing the dam, and has a broad prospect for its application.
The innovative results are as follows:
1. The In-Chamber Single Longitudinal Culvert with Double Open Ditches Filling and Emptying System has been adopted in large navigation locks for the first time among the locks home and abroad.
2. The relationship between the layout of the baffle wall and the lateral flow distribution has been studied in detailed by models tests, and the most suitable baffle wall layout for Guiping 2nd lane lock has been determined finally.
3. According to the actual geological conditions and the berthing condition test results, the layout optimization of the double open ditches has been put forward, which further improves the berthing conditions and reduces the bottom excavation, the mooring force of the designed vessel is only 25% of the single open ditch layout, and it saved the project investment of 43 minllion yuan.
4. The advantages of the new filling and emptying system have been validated through prototype observation, and the operation conditions have been further improved by prototype debugging.
5. Comparing to other In-Chamber Longitudinal Culvert Systems, the new filling and emptying system has the advantages of more sufficient energy dissipating, greater hydraulic performance and smaller cost.