On January 31, 2024, the Baihetan Engineering Construction Department of China Three Gorges Construction Engineering Group officially handed over the Baihetan Hydropower Station dam to the Yangtze Power Baihetan Power Plant of China Three Gorges Group to take over and operate it. Completing the handover of this dam project, which ranks second in the world after the Three Gorges Project, means that the Baihetan Hydropower Station project has entered the full operation period from the construction period and will usher in a new stage of official operation.
The dam is the core building of the hydropower hub project and is responsible for retaining water and releasing floods. Its quality and safety directly determine the life of the hub project. The Baihetan Hydropower Station dam is a 300-meter concrete double-curved arch dam. The first warehouse was poured on April 12, 2017, and the entire line was poured to the top on May 31, 2021, which lasted 1,511 days and nights.
The problem of temperature control and crack prevention of large-volume concrete has always been a worldwide problem. People in the industry say that “no dam will crack.” However, there is no single crack in the dam at the Baihetan Hydropower Station. “This is a miracle of dam construction!”
During the dam’s construction, it overcame a series of world-class problems, such as columnar jointed basalt and the safe and efficient operation of the cable crane group under strong wind conditions. It also carried out technological innovations such as using low-heat cement throughout the dam and intelligent construction and built a seamless and high-quality dam.
To check the concrete construction quality of the dam, 848 meters of holes were drilled in the entire dam, and a total of 6 cores with a length of more than 20 meters were taken out. A layer of cooling water pipes took out the world’s longest normal concrete core sample with a length of 36.74 meters. After careful on-site inspection, the concrete core sample was complete and beautiful, with a smooth and flat surface, even aggregate distribution, and good inter-layer bonding.
Previously, China Central Television reported how the Baihetan Hydropower Station dam prevents temperature cracks, which is the highest level of mass concrete crack prevention technology in China and even the world. The Baihetan Hydropower Station dam is 289 meters high and is divided into 31 dam sections for construction. A total of more than 8 million m³ of concrete was poured.
Temperature control and crack prevention of large-volume concrete have always been a difficult problem in the engineering community. To ensure that the dam does not have temperature cracks from the source, the entire Baihetan dam uses a new type of special cement independently developed by China for the first time – low-heat Portland cement concrete.
Traditional dam construction requires pouring a large amount of concrete. The cement hydration reaction in the concrete will generate heat, causing the temperature of the concrete to rise after it is poured and then slowly cool to ambient temperature. If effective temperature control measures are not taken and the concrete can expand with heat and contract with cold, cracks will inevitably occur. The heat of hydration of low-heat cement concrete is lower than that of medium-heat cement and ordinary cement, and the adiabatic temperature rise is much lower than that of medium-heat cement and ordinary cement. It can greatly reduce the possibility of dam cracks caused by thermal expansion and contraction, and low-heat cement has the advantages of good dry shrinkage resistance, erosion resistance, impact resistance, wear resistance, and high strength and continuous strength growth in the later period.
Concrete pouring for the main body of the dam began on April 12, 2017. It has lasted 1,510 days and nights. Two thousand two hundred fifty-three warehouses and 8 million cubic meters of concrete have been poured into the dam body. During the more than four years of dam pouring, all parties involved in the construction worked hard day and night, and the overall balance of the dam continued to increase. The pouring volume has exceeded 2 million cubic meters for three consecutive years, creating an annual pouring of 2.7 million cubic meters, a monthly pouring of 273,000 cubic meters, A world record for the 100-day deep hole crossing and other similar projects.
At the Baihetan construction site, high temperatures above 35 degrees Celsius are the norm. According to calculations, it takes about 7 minutes for the concrete poured at Baihetan Dam to come out of the mixing building, drive to the feeding platform through a dump truck, and then transport the concrete to the dam pouring site through a cable car. In the constantly changing environment and high temperature, Regardless of weather conditions, the temperature of the concrete arriving at the site will not exceed 8 degrees Celsius.
Xu Yinlin, chairman of China Water Resources and Hydropower Fourth Engineering Bureau Co., Ltd., said: First of all, during the operation of the mixing system, we must first pass the fruit materials through one cold and two colds to ensure that the temperature of the fruit materials drops to the temperature requirements. , so that the outlet is guaranteed to be at 7 degrees. The concrete is introduced into the cable crane tank through an insulated truck and quickly put into the warehouse. Then, we spray and moisturize during the pouring process and insulate immediately to prevent the temperature from rising.
During the dam’s construction, the intelligent water supply equipment and multi-terminal control system jointly developed by China Three Gorges Corporation and Tsinghua University achieved intelligent and precise control of the concrete temperature process by sensing the concrete temperature in real-time and dynamically controlling the water flow.
The Baihetan Hydropower Station will be lowered to store water on April 6, 2021, and will be fully operational on December 20, 2022. The dam has experienced three flood season tests, and the reservoir has been impounded to normal water storage levels twice. Various operating indicators such as temperature stress, deformation and displacement, and seepage and seepage pressure of the dam body are better than the design level, and the working performance is good. Next, the Baihetan Engineering and Construction Department will continue to be prudent and do a solid job in contract acceptance, laying a solid foundation for the special acceptance of the hub project in the completion stage.
Supplier
TRUNNANO(cabr-concrete.com)Â is a supplier of concrete crack reducing admixture and other concrete additives, which is concrete and relative products with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high quality concrete crack reducing admixture, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com).