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BEIJING, Feb. 23 (Xinhua) -- On the upper reaches of the Jinsha River in southwest China, a high altitude hydropower station is under construction. Notably, the significant difficulty of temperature control and crack prevention during the concrete pouring process in such a cold and high-altitude area has been overcome by the construction team. The Yebatan Hydropower Station is located at the junction of Baiyu County in southwest China's Sichuan Province and Konjo County in Xizang Autonomous Region, which is also in the southwest of China. With the highest elevation of nearly 2,900 meters -- this hydropower station features a 217-meter-high arch dam and total installed capacity of 2.24 million kilowatts. "Cracks are always troublesome for the pouring of concrete dams," said Du Guangyuan, an engineering management department director at Huadian Jinsha River Upstream Hydropower Development Co., Ltd. Even the tiniest cracks can have a negative impact on durability, thus shortening the service life of dams. "Pouring a concrete dam is like baking a cake," said Du. After injecting raw material into the mold, constructors wait for the dam to take shape "but the former is far more complicated than the latter." During pouring, the exterior of the concrete cools rapidly, while the interior heat continues to accumulate due to the hydration reaction of cement. This temperature difference generates internal stress. If the stress exceeds the concrete's tolerance limit, cracks will slowly emerge -- weakening the structural strength of the dam and reducing its load-bearing capacity. The harsh environment found in high-cold and high-altitude areas, with longer winters and shorter spring and autumn periods, increases the risk of cracks, and constructors had to bear this in mind at the Yebatan Hydropower Station. Building such a dam would clearly be a challenge given the weather conditions at its construction site. "Old concrete cracking prevention methods were almost ineffective here," said Zhong Fulin, an assistant director with the engineering management department. An aerial drone photo taken on Nov. 5, 2024 shows the construction site of Yebatan Hydropower Station in southwest China. (Xinhua/Shen Bohan) After countless trials and discussions, the construction team came up with an imaginative solution, building an "air-conditioned house" for the dam. To maintain thermal insulation, they sprayed polyurethane on the upstream and downstream surfaces of the dam, and laid plastic film on the deck and transverse crest areas -- effectively maintaining a moist environment, Zhong explained. Through such determined and skilled efforts, they managed to install three-layer insulated covers while adding heating facilities, such as air heaters, on the surface to ensure that the concrete maintained an appropriate temperature range after pouring. In the end, the construction team succeeded in achieving year-round concrete dam pouring. Currently, they are also applying intelligent systems to control the temperature of the dam in carrying out efficient grouting. The intelligent temperature control system is capable of monitoring the internal temperature changes in real-time and with precision. It can respond swiftly if any abnormality is detected -- and is capable of automatically switching to either heating or cooling mode. Construction of the main project of the hydropower station started in September 2018, with its first group of units expected to be put into operation by the end of 2025. The hydropower station will be able to generate 10.2 billion kilowatt-hours of power annually, saving almost 4 million tonnes of coal and cutting carbon dioxide emissions by 7.37 million tonnes per year. 原文链接： 原文大意： 北京2月23日电（新华社）在中国西南部金沙江的上游，一座高海拔水电站正在建设中。值得一提的是，施工团队克服了在寒冷高海拔地区进行混凝土浇筑过程中温控和防裂的重大难题。 叶巴滩水电站位于中国西南部四川省白玉县与中国西南部的西藏自治区江达县交界处。 这座水电站的最高海拔近2900米，建有一座217米高的拱坝，总装机容量达224万千瓦。 华电金沙江上游水电开发有限公司工程管理部主任杜广元表示：“对于混凝土大坝的浇筑而言，裂缝一直是个棘手的问题。”哪怕是最细微的裂缝，都会对大坝的耐久性产生负面影响，从而缩短大坝的使用寿命。 杜广元说：“浇筑混凝土大坝就像烤蛋糕一样。”把原材料注入模具后，施工人员就等着大坝成型，“但前者远比后者复杂得多”。 在浇筑过程中，混凝土外部迅速冷却，而内部由于水泥的水化反应，热量会持续积聚。这种温差会产生内应力。 如果内应力超过混凝土的承受极限，裂缝就会慢慢出现，进而削弱大坝的结构强度，降低其承载能力。 高寒高海拔地区环境恶劣，冬季漫长，春秋季节短暂，这增加了出现裂缝的风险，叶巴滩水电站的施工人员不得不时刻牢记这一点。考虑到施工现场的天气条件，建造这样一座大坝显然是一项挑战。 工程管理部主任助理钟福林说：“以往的混凝土防裂方法在这里几乎不起作用。” 经过无数次的试验和讨论，施工团队想出了一个极富创意的解决方案：为大坝建造一个“空调房”。 钟福林解释说，为了保持隔热效果，他们在大坝的上下游表面喷涂了聚氨酯，并在坝顶和横向坝顶区域铺设了塑料薄膜，有效地保持了湿润的环境。 通过这样坚定而巧妙的努力，他们成功安装了三层隔热罩，同时在表面添加了空气加热器等加热设备，以确保混凝土在浇筑后保持在合适的温度范围内。 最终，施工团队成功实现了混凝土大坝的全年浇筑。 目前，他们还在运用智能系统来控制大坝的温度，以实现高效灌浆。 智能温控系统能够实时、精确地监测大坝内部的温度变化。一旦检测到任何异常情况，它能迅速做出反应，还能够自动切换到加热或冷却模式。 该水电站的主体工程于2018年9月开工，首批机组预计于2025年底投入运行。 这座水电站每年将能够发电102亿千瓦时，每年可节约近400万吨煤炭，减少737万吨二氧化碳排放。 |
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