Nanjing Yangtze River Management Office: steadily promote the Baguazhou branch river regulation project

Baguazhou branch is located in the middle and lower reaches of Nanjing Reach of Yangtze River, starting from Xiaguan of Gulou District and ending in Xibasou of Liuhe District. The total length of the river is about 18 kilometers, with the south branch as the main branch and the north branch as the branch. With the approval of National Development and Reform Commission and Provincial Development and Reform Commission, it was decided to implement the river renovation project of Baguazhou branch of Nanjing reach of Yangtze River. Nanjing Changjiang River Management Office set up the project construction headquarters to steadily promote the river renovation project of Baguazhou branch of Yangtze River.

The two sides of Baguazhou branch are concentrated with petrochemical, steel and electric power industry group, which is an important economic hinterland of Nanjing. In recent years, the bifurcation ratio of North Inlet has been decreasing and the flow condition has been deteriorating, which has caused adverse effects on the normal operation of hydraulic facilities of important economies along the North Inlet. To carry out the river renovation project of the branch of Baguazhou of Yangtze River plays an important role in controlling and stabilizing the river regime, ensuring flood control safety and promoting the economic and social development of our city.

In March and November 2018, the National Development and Reform Commission and the Jiangsu Provincial Development and Reform Commission respectively approved the feasibility study report and the preliminary design report of the project, and agreed to implement the river renovation project of Baguazhou branch of the Nanjing reach of the Yangtze River. The total investment of the project is 476 million yuan, and the total construction period is 24 months. The main construction contents of the project include: strengthening the underwater mouth of Baguazhou Zhoutou at 310 meters; 169,100 square meters of deep chute protection project for south branch of Zhoutou was implemented; South branch bottom protection project downstream flow of 450 meters, an area of 369,000 square meters; The original shore protection project to reinforce Zhoutou, Shangba, Yanzi Ji and Tianhekou is 7,270 meters long.

Under the care and guidance of Provincial Water Resources Department and Municipal Water Bureau, the project started construction in December 2018. During the construction of the project, the construction department strictly followed the basic construction procedures of key water conservancy projects, closely surrounding the strategic requirements of the Yangtze River Great protection, and promoted the project construction in an orderly manner. At present, the total investment has been completed at 212 million yuan, with the progress of about 48.6\%, meeting the requirements of the schedule.

It is understood that the water flow rate of the project area is large, the river trough is deep, the flow field is disordered, and the construction conditions are extremely bad. At the same time, the project is also located in the main waterway of the Yangtze River and the edge, so the safety risk of the project implementation is extremely high. The construction department actively communicated with the waterway and maritime authorities, and implemented a number of targeted measures, including setting up special navigation markers, setting up special on-site warning ships, implementing 24-hour water alert, channeling and directing passing ships, to ensure the smooth implementation of the project. In view of the difficulty of construction, the project is located in the area of the fish mouth and the south side of the island head, the deep trough with a depth of minus 40 meters has strong transverse flow and two directional changes, and the underwater bank slope is steep, the deep trough protection works should be carried out during the implementation of the project, mainly by throwing about 1.23 million cubic meters of sand bags to fill the deep trough. After optimizing the construction scheme, optimizing the construction vessel, introducing advanced underwater monitoring system and other measures, the multi-pronged approach ensures that the sand bag throwing construction quality is under control.

In the construction of Baguazhou and Mufushan Yangtze River channel bottom protection, the domestic advanced technology of concrete block soft sediment drainage and bottom protection is adopted. Because this water area is located in the main waterway of the Yangtze River, the water depth is more than 40 meters, and there is oblique mainstream impact, the operating conditions are the worst in the Yangtze River lower regulation project. Relevant construction departments attach great importance to the formulation of targeted construction plans and dozens of special engineering measures to ensure the Yangtze River regulation and protection of the bottom of the water construction safety, to ensure the quality of the project.

Article source: Nanjing Daily