When the ordinary steel gate operates in the northern region for ice protection in winter, the ice pressure directly acts on the steel gate leaf and directly destroys the gate leaf. Thus, the safety factor value of the Hydraulic elevator dam shall be appropriately increased in the early stage of metal structure design. Through theoretical calculation and computer simulation analysis, the gate leaf of the gate body shall be made of high-strength alloy steel. The plate thickness is also higher than that of ordinary steel gate. For the gate body with ice passing requirements, grade D and E steels with low temperature toughness shall be selected according to the ambient temperature conditions.
Due to the existence of dynamic ice pressure, the deflection of the rotating shaft of the ordinary steel gate is greatly increased, which destroys the stability of the lifted gate. When the Hydraulic elevator dam meets the water storage and ice retaining in northern region during frizzing period, the lock of the gate body is released, and the thick and short plunger cylinder hydraulic elastic support is adopted in the structure, which can alleviate the damage caused by dynamic ice pressure to the gate leaf structure of the gate body to a certain extent.
The electro-hydraulic joint control system is operated to retreat ice pressure. The maximum oil pressure upper limit of the hydraulic system is set to resist static ice pressure. So that the system could realize overpressure relief and periodic slight jacking of the gate leaf through the cooperation of the bypass overflow valve group and the electrical control system. It could break the ice in front of the gate and break the destructive effect of static ice pressure on the gate.
The bottom plate of the Hydraulic elevator dam adopts an open low step structure. The gate body and the supporting hydraulic cylinder act on the same steel connecting base, so that the gate body, the supporting hydraulic cylinder and the embedded parts form a triangular integral stable structure. This structure alleviates the impact of static ice pressure on the overall action of the gate body and the supporting hydraulic cylinder. For the open step design, the hydraulic cylinder is fully open without local pit, which greatly avoids the adverse impact of freezing and sand on the hydraulic cylinder in the pit. It is easier to discharge ice cream, avoid the problems of sedimentation, freezing and difficult maintenance of pits, and prolong the overall service life of Hydraulic elevator dam.
Due to the flood discharge in freezing period, the gate body lies down and there is ice sheet breaking overflow. The gate will bear the dynamic ice pressure, and the broken ice sheet will impact the gate structure along with the water flow. Through the optimization of the shape and structure of the Hydraulic elevator dam, the influence of dynamic ice pressure can be effectively alleviated by configuring a water carrying member on the top of the arc rib on the upstream side of the gate leaf. For the arc rib on the upstream side of the gate leaf, the broken ice cover first contacts with the arc rib, and the impact force is dispersed to the whole gate body through the rib, reducing the direct impact on the gate leaf. The rigidity and bending resistance of the gate body enhanced by the rib plate. The arc shape is reasonable for the effect of guiding the ice layer to climb over the gate top, and the interval arrangement is conducive to the role of cutting and combing ice. The water carrying member on the top could carry water at the top to prevent water flow close to the wall, and heavy ice layer will not be formed on the back water side of the gate body. Thus, it will not increase the burden of the driving mechanism.
This technology has been applied to six Hydraulic elevator dam projects in Mudanjiang, Dunhua, in Jilin Province. After the project is completed, it will retain water in dry season and form a lake in the urban area which could be used as a wide natural ice rink in winter. The ice rink will be served as an entertainment place for local residents, attract tourists, promote the development of tourism and economic prosperity in Dunhua City, and become one of the local "top ten livelihood projects". At present, the Hydraulic elevator dam with the longest operation time has been tested by ice storage operation for six winters.
It has been successfully applied in Songjiang River and Songhua River in Fusong, Jilin, Lanxi Hulan River in Heilongjiang, Antu burhatong River in Jilin, Xiaoling River in Chaoyang, Liaoning, Baotou City Park in Inner Mongolia, Nanchuan River and Yanhe River in Yan'an, Shaanxi.
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