The Yangtze River stretches ten thousand li, with its danger lying at Jingjiang and its difficulty at Dongting. As the "main battlefield" for flood control in the Yangtze River Basin, Dongting Lake receives floodwaters diverted from the Yangtze through the three outlets of Songzi, Taiping, and Ouchi to the north, and the inflows of the four rivers Xiang, Zi, Yuan, and Li to the south, forming an intricate river-lake relationship and a tangled network of rivers and lakes.

To improve the flood control and disaster reduction system of the Dongting Lake area and enhance the flood control capacity of the embankments, in September 2022 the Phase I Project of Embankment Reinforcement for Key Polders in the Dongting Lake Area of Hunan officially commenced. Following the approach of "systematic governance, phased construction, and polder-by-polder compliance," the project first carried out comprehensive compliance reinforcement on six key polders, among which the Anzao Polder is being built by the Ninth Bureau of Hydropower under Power Construction Corporation of China (PowerChina).

Over the past two years, the project team has developed new quality productive forces tailored to local conditions and, through a series of innovative measures, achieved remarkable results in work safety, technological efficiency, and enterprise-local community co-construction.

Implementing new ideas makes work safety more heartfelt

The Anzao Polder is located in Anxiang County, Changde City, Hunan Province. Its first-line main dike is about 81.5 kilometers long, and the protected area of the polder reaches 204.6 square kilometers. The project faces unfavorable factors such as a wide construction scope, extensive water-related operations, and high flood control pressure, posing severe challenges to work safety.

"At the Liujiadu Sluice construction site, materials are stacked beyond the safe height and protective measures are inadequate, posing a safety hazard." The safety grid inspector reported the problem in the work group, and soon a dedicated person rectified it and recorded it on file. After implementing grid-based management, the project department divided the area into four work zones, each equipped with a zone chief and Level 1, 2, and 3 grid inspectors, building a management system in which "safety has a grid, the grid has cells, each cell has a designated person, and each person bears responsibility." Since the beginning of the year, 42 hazards have been identified. In addition, the project department has vigorously carried out safety knowledge education, special campaigns on work safety, and emergency skills training, and conducted training and assessments on on-site violations, risky operations, and major accident hazards. Thanks to the efforts of numerous grid inspectors, safety "loopholes" are promptly detected and eliminated, and more people's safety awareness has been enhanced.

In terms of institutional development, the project department actively promotes the "one meeting and three cards," namely the pre-shift meeting, the safe operation card, the emergency response guide card, and the safety inspection card. At the pre-shift meeting, safety grid inspectors check work safety conditions, review and summarize, listen to suggestions, and conduct briefings. During construction operations, the safe operation card specifies operating procedures, safety training, and operation approval; the emergency response guide card specifies post risk identification, post injury scenarios, emergency response measures, and emergency contacts. During hazard inspections, the safety inspection card records and publicly discloses identified hazard sources and prevention and control measures. The "one meeting and three cards" system has clear processes and well-defined responsibilities; on a construction site with more than 500 workers per day at peak times, not a single work safety accident has occurred.

In the construction area of the first-line main dike, "round" probes are often seen. They can not only rotate 360 degrees but also upload data in real time, allowing construction progress and safety conditions to be monitored through the monitoring system. "In addition to the monitoring system, the smart construction site built by the project also has functions such as flood control and personnel and equipment supervision. For example, scanning the QR code on the side of a safety helmet pops up project management personnel information, which is very convenient to use," introduced Zhang Qiyi, the project's safety director. Underwater riprap placement is an important part of the embankment reinforcement project and also a high-risk operation. For this reason, the project department introduced drones, assault boats, underwater sonar detectors, and other equipment to carry out special emergency drills, effectively improving the efficiency and accuracy of rescue and creating a sound, safe, and stable environment.

By using the above new ideas, the project progressed safely and orderly. The project department has repeatedly ranked among the top in the owner unit's safety and environmental protection inspection assessment and hazard governance assessment, and at the beginning of the year was rated as a "Standardized Model Site for Safe and Civilized Construction" in Anxiang County's water conservancy construction for 2023.

Broadening new paths makes technological efficiency more dedicated

The flood season of Dongting Lake runs from April to September each year, leaving the Anzao Polder with less than six months of effective construction time annually. How to complete the construction tasks within the limited time and efficiently apply various technologies to the embankment reinforcement project became a difficult problem facing the project team.

The geological conditions in the Dongting Lake area are complex. Over the years, the main dike has been reinforced many times, and the original riprap toe protection has been buried by later soil layers. Therefore, selecting an appropriate soft foundation treatment method is particularly necessary. Based on the actual engineering conditions, the project team selected the mature cement-soil mixing pile construction technique to effectively solve the soft foundation treatment problem by improving foundation bearing capacity and reducing settlement. During mixing pile construction, phenomena such as drill jamming and unsatisfactory pile formation occasionally occurred. The project team used physics-informed neural networks and multi-scale numerical simulation to achieve accurate modeling and intuitive prediction of geological structures. In the field of excavation-free construction for embankment projects, the project team innovatively introduced intelligent equipment and optimized system parameters, using modular design and new sensor technologies to enhance the overall flexibility and stability of construction operations, achieving the expected results of efficient, low-cost integrated construction.

Cutoff walls have functions such as preventing groundwater seepage, protecting foundation stability, and ensuring the safety of structures, so their importance is self-evident. After on-site research, the project team found that the triaxial pile machine used in the original design scheme had shortcomings such as low efficiency, high energy consumption, and unstable quality. After extensive market research and production tests, the project team decided to introduce TRD (Trench cutting Remixing Deep wall) process equipment for the first time in the Phase I Project of Embankment Reinforcement for Key Polders in the Dongting Lake Area, and to use XY-2 geological drilling rigs to obtain representative core samples, evaluate the material composition, uniformity, density, and possible defects of the cutoff wall, and comprehensively grasp the overall quality of the cutoff wall. After implementing a "combination punch" of measures, the impact on joint quality was effectively reduced, and the seepage control effect of the main dike was greatly improved.

Within the implementation scope of the Anzao Polder, there are about 240,000 square meters of TRD cutoff wall and about 525,000 square meters of cement-soil cutoff wall, characterized by many points, a wide area, and a long front. To improve construction efficiency, the project department established a scientific and technological research team to repeatedly discuss construction methods. On the premise of ensuring project quality, they successfully simplified the TRD cutoff wall "three-step method" (cutting-retraction-mixing and grouting to form the wall) into a "one-step method" (cutting, mixing, and grouting to form the wall), and simplified the cement-soil cutoff wall "four mixings and two sprays" (grouting and mixing to sink-grouting and mixing to lift-re-mixing to sink-re-mixing to lift) into "two mixings and two sprays" (grouting and mixing to sink-grouting and mixing to lift). Under the same conditions, the construction efficiency of the TRD cutoff wall increased nearly twofold, and that of the cement-soil cutoff wall increased nearly onefold, while effectively reducing inputs such as labor, equipment, and fuel.

Through optimizing construction techniques, introducing advanced equipment and technology, and carrying out research on key topics, the project department has achieved fruitful scientific and technological innovation results, obtaining honors including 34 authorized invention and utility model patents, 6 approved scientific research topics, 1 provincial and ministerial-level construction method, 3 QC achievements, and 1 TGQ.

Presenting a new image makes enterprise-local co-construction more heartwarming

Doing work that reaches the people's "hearts" and thinking ahead of the people. Adhering to the concept of enterprise-local co-construction, the project department sincerely does practical and good deeds for the people, adding strong momentum to creating a new situation of harmonious project construction and establishing a good corporate image.

Strolling on the main dike, the splashing sound of waves interweaves at the dike toe, and a gentle breeze blows from the river, bringing full comfort and coziness. Today, walking on the main dike has become part of the daily routine for many county residents. "The flood-control road surface on the dike top in the Anzao Polder embankment reinforcement project is 73.19 kilometers long. To facilitate local residents' travel and provide a public space for water-adjacent recreation and healthy leisure, we prioritized construction of the 8-kilometer dike section within the urban area, laying asphalt over the original uneven concrete road surface, widening the road, and building steps and planting abundant vegetation on the slopes on both sides of the dike. Now the lush green dike has become beautiful and pleasing to the eye," said Liang Zhenlong, deputy chief engineer of the project.

"Thank you to the Ninth Bureau of Hydropower for its care and love. We will repay everyone with practical actions and make the county's living environment cleaner and tidier," said sanitation workers happily after receiving "love gift packages" from volunteers. In the winter of 2023, after careful observation, project volunteers found that in Anxiang County, where the project is located, the sanitation worker group is large, covers a wide area, and works long hours. To convey love and warmth, the project department actively planned a volunteer activity and contacted the Anxiang County Urban Management and Law Enforcement Bureau. During the activity, project volunteers gave concentrated presentations on health knowledge such as the prevention and improvement of common occupational diseases and winter infectious diseases, and personally distributed prepared fresh fruit and daily necessities to more than 430 sanitation workers.

This summer, a breach occurred in the first-line dike of Dongting Lake at Tuanzhou Polder in Yueyang, Hunan, touching the hearts of people across the country. Immediately after the emergency, the project department established a flood control and emergency rescue team with Party members as the backbone, allocated 270 sets of steel wire gabion nets and other emergency supplies and delivered them to the disaster site, and fully assisted local relevant departments and rescue units in disaster response. At the same time, according to the flood control and flood season plan, the project department promptly prepared emergency rescue material reserves, purchasing a total of 20,000 woven bags, 10,000 square meters of tarpaulin, 5,000 square meters of geotextile, 1,000 meters of steel wire rope, 200 life jackets, 200 strong flashlights, 200 jin of iron wire, 100 shovels, and 50 life rings, and stationed 19 excavators near the project site, ready to join emergency rescue at any time, winning praise from the local flood control and drought relief headquarters.

From building public welfare and livelihood projects to carrying out heartwarming volunteer services, and to actively engaging in flood control and emergency rescue at critical moments, the project department puts social responsibility and the duties of a central state-owned enterprise into practice and reflects them in details, writing a story of "deep affection like fish and water" between PowerChina and the local people.

The road of "innovation" is never smooth. As one of the 150 major water conservancy projects deployed and implemented by the State Council, the Key Polder Embankment Reinforcement Project in the Dongting Lake Area has extensive social benefits and good economic benefits. The project team will continue to summarize experience, work with fine craftsmanship to benefit the people, and strive to expand a "new track" of "building one project, erecting one monument, earning one profit, opening up one market, and cultivating one batch of talent."

Rendering of the completed project