The the Pearl River Delta Water Resources Allocation Project, as a major water conservancy infrastructure in the Guangdong Hong Kong Macao Greater Bay Area and one of the 172 major national water conservation and water supply projects, has been completed with the participation of Sinohydro Bureau 4. The project takes water from the Xijiang River in Liyuzhou, Shunde, Foshan, and continuously injects it into the Luotian Reservoir and Gongming Reservoir in Shenzhen through underground pipes and channels. At present, the project has been officially opened to water and entered the initial operation stage, providing reliable water resources guarantee for the sustainable development of the Guangdong Hong Kong Macao Greater Bay Area.

Guangdong has long faced the challenge of uneven spatial and temporal distribution of water resources, especially in the eastern part of the the Pearl River Delta, where the permanent population and economic development account for an important proportion of the province. However, the development of water resources in the Dongjiang River Basin is approaching its limit, while the utilization rate of water resources in the Xijiang River Basin is relatively low. Therefore, diverting water from the West River to solve the water use problem of the East River has become a key measure to solve this problem.

The the Pearl River Delta Water Resources Allocation Project is a 113.2 km long water transmission pipeline, which starts at Liyuzhou, Shunde, the main stream of the West River, crosses Nansha in Guangzhou, and finally reaches Gongming Reservoir in Shenzhen. The designed flow rate of this project is 80 cubic meters per second, which can provide 1.708 billion cubic meters of water annually and benefit over 32 million people.

In the construction tasks of D1 and D2 sections undertaken by China Hydropower Fourth Bureau, D1 section includes multiple key facilities such as Luotian pump station, inlet gate, drilling and blasting tunnel, temporary cofferdam, top pipe tunnel, working well, and SZ30 working well renovation project of Shenzhen branch trunk line test section project. Among them, the length of the drilling and blasting tunnel is 1.4 kilometers, the length of the top pipe tunnel is 1.98 kilometers, and it is also responsible for the construction of six working wells. The D2 section covers drilling and blasting tunnels, shield tunnels, working shafts, pressure regulating shafts, maintenance access tunnels, as well as the entrance facilities and access roads of the Luotian Tunnel. Among them, the length of the drilling and blasting method tunnel is 6.95 kilometers, and the length of the shield tunnel is 3.4 kilometers.

In May 2019, the construction of the the Pearl River Delta Water Resources Allocation Project was fully started. Among them, the D1 and D2 sections serve as the final stages of the engineering water transmission line. The successful completion of these two sections marks that the the Pearl River Delta Water Resources Allocation Project is about to be fully completed, which is of vital significance for the integrity and smooth operation of the whole project.

The the Pearl River Delta has a dense river network, densely distributed buildings, and complex and changeable geological conditions, which make the region known as the "Geological Museum". In this region, the combined effect of hydrological and geological factors poses great challenges to construction, but at the same time, it has also spurred technological innovation and engineering breakthroughs.

In order to minimize surface interference and provide sufficient underground space for subsequent urban infrastructure and transportation facilities, the engineering tunnel has chosen the deep buried shield tunneling water delivery method. This method places water pipelines in a space of 40 to 60 meters underground, which is usually three times the depth of subway construction. In order to ensure the stability of the working well and a solid foundation for tunnel construction, the project team strictly controlled the selection of mud materials and optimized the construction process.

In order to ensure that the shield tunneling machine can smoothly pass through various risk areas, the project team actively adjusts the jacking parameters of the shield tunneling machine and the pipe jacking machine, and optimizes the mix ratio of the thixotropic mud. They have strengthened the monitoring of geological subsidence and creatively adopted the mud control method. This method successfully overcame the problems of poor rock quality and great construction difficulty, and safely crossed the strata of Shenzhen Metro Line 6 branch line and Xinpitou River. Through these measures, the occurrence of settlement has been effectively avoided, ensuring the safety of the ground and buildings.

During the construction period, the excellent performance of achieving a maximum daily excavation of 24 meters and a maximum monthly excavation of 342 meters was awarded to the construction unit. The monthly peak award for shield tunneling with a diameter of 6 meters in 2020 has repeatedly topped the construction dragon tiger list and the Pegasus list for the entire project line. To ensure the quality of tunnel lining construction, the project department adopts rare prestressed technology to continuously improve the efficiency of prestressed concrete pouring. By pre laying waterproof cloth for initial support, the pressure water discharge method behind the back is used to overcome the difficulties of drilling and blasting tunnels, such as broken strata and large seepage, effectively reducing the occurrence of cracks and ensuring the quality of lining construction. The pouring of tunnel concrete lining is completed 13 days ahead of schedule.

The shield tunneling section and drilling and blasting section of this project are partially lined with steel pipes, resulting in a smaller tunnel clearance and a larger volume of steel pipes, which poses great difficulties for transportation and installation. To address these issues, the project department has customized a dedicated trolley to improve the transportation speed and installation accuracy of steel pipes. In the subsequent self compacting concrete pouring process, the project department installed a pressure gauge on the ground pump and an exhaust valve at the steel lining pouring port to ensure the quality of concrete pouring.

In order to improve the efficiency of the civil construction of the Luotian pumping station, the project department optimized the construction process reasonably and adopted the technology of plain concrete for the first time. The application of this technology provides high-quality working surfaces and various reserved interfaces for mechanical and electrical installation, metal structure construction, and decoration, ensuring the smooth progress of construction. During the construction period, the project department steadily promoted the construction of "smart construction sites" and gradually implemented standardized and intelligent construction with "BIM+GIS" as the core technology. This measure has created a strong atmosphere for construction, improving the efficiency and quality of construction.

This project team has achieved fruitful results in the research and implementation process. They have successively completed 5 invention patents, which is recognition and protection of their innovative achievements. In addition, their research results have also been recognized by Electric Power Construction Group and won two Science and Technology Research Achievement Awards. In the provincial and group level evaluations, this team also performed excellently. They have won multiple awards, including the Qinghai Provincial Science and Technology Progress Award, Qinghai Provincial Innovation Achievement Award, and the Electric Power Construction Group Science and Technology Progress Award, fully demonstrating their strength in technology research and development and achievement transformation. Keywords: engineering construction, engineering news, engineering construction information.

After the Pearl River Delta water resource allocation project is put into operation, it will achieve a pattern of west water and east water, changing the single water supply situation in Nansha District, Shenzhen City, and Dongguan City of Guangzhou. This project will improve the water supply guarantee rate and provide emergency backup water sources for Hong Kong, Guangzhou Panyu, Foshan Shunde and other places. In addition, the project can gradually return the ecological water used in the Dongjiang River Basin, further ensuring the water supply and ecological security of the Guangdong Hong Kong Macao Greater Bay Area. (This article is from the official website of Jiandao: www.seetao. com. Reproduction without permission is not allowed, otherwise it will be punished. Please indicate Jiandao's website and the original link when reprinting.) Jiandao's mechanical column editor/Zhou Yingwen