I. Service life
The design service life of steel dam gate can reach 50~60 years, and the longest service life in the world is nearly 100 years. The earliest Xiaoxi hydropower station in Fujian was built in 1958, and it is still in use today. Cases of using the same steel structure before liberation abound. According to the indoor test data and engineering practice, the authoritative department preliminarily judges that the rubber dam must be replaced once within the service life of 10~ 15. So far, the service life of the first rubber dam in China has not exceeded 15 years. Many rubber dams built in Northeast China in the last century were demolished, and the rubber dam built in Sundong Power Station in Guangxi in 2005 was also demolished and the steel gate was rebuilt. The investment of a steel dam gate is equal to the investment of four rubber dams (excluding a lot of auxiliary construction work in the middle).
Second, the damage and maintenance
(1) Damage caused by man-made destruction
Rubber dams are easily damaged by sharp objects, and rubber dams should not be installed in places that are prone to serious repeated damage due to ignorance or malicious damage.
2) The damage caused by debris flow after the flood and its impact on the landscape.
Due to all kinds of debris left after the flood, sharp objects such as civil facilities and building materials are likely to damage the upstream surface of the dam. Small air leakage is easy to repair, however, if the air leakage area is large, such as the air leakage caused by the rubble of a building, it is more difficult to repair. And all kinds of debris left on the dam have a great influence on the landscape. At present, every time the dam breaks, the operation unit sends people to scrub it, and the workload is very heavy.
(3) Damage caused by deflation
In the process of discharging water, the dam body of rubber dam may be punctured by sharp objects near the downstream surface of the dam.
(4) Damage caused by wear and tear
The vibration of the dam, the friction between the dam and the river bed, the two banks and the floating garbage may all lead to the friction loss of the dam.
(5) Damage caused by fire
1. Fire may be the most unfavorable potential risk factor of rubber dam. Fire will cause large-scale dam damage, but sometimes it is impossible to repair large-scale dams. For very important dams, it is feasible to provide spare rubber dams so that they can be replaced quickly in case of serious damage.
2. The nature of the rigid gate itself determines that the above situation will not happen. Here, we have made a detailed analysis of the rigid gate. At present, the moving parts of the gate are made of special composite materials MGA and MGB, which do not need lubricating oil and will not rust after running underwater for several years.
3. Recently, it was reported that the Xiaobudonghe rubber dam in Linyi City, Shandong Province has been in operation for five or six years, and the dam body has been repaired three times, with a cost as high as 6 million yuan (excluding others), while the steel gate can be corroded once in about 30 years.
Third, the operation situation
1. Running time Rubber dam is raised by inflating or filling water, which generally takes 2~3 hours to completely raise or break the dam, which takes a long time. The rigid gate is opened and closed by the hoist, and the running speed can reach 1~2m/ min. Our company can open and close the gate in less than 2 minutes. This can effectively ensure timely flood discharge in case of sudden flood. With the increase of service times and service life, the rubber dam will use inflation (water) and exhaust (water) for a long time because of scaling in the dam and pipeline.
2. Reliability of use
(1) The leakage of rubber dam is due to cross-linking and puncture of rubber film, defects in pipeline connection, fastening system and construction quality. Therefore, it is necessary to inflate continuously, otherwise the phenomenon of dam deflation (water) will collapse automatically after a period of time, and sometimes the water in the river is unknown, causing certain losses. However, the steel dam gate is mechanically locked, so the angle can always be locked when the gate is opened or closed or the water level is adjusted, and it will not move.
Step 3 shake
It is clearly stipulated in the design code of rubber dam that the overflow should not exceed 50cm, otherwise the dam-crossing event will occur, and the steel dam gate can effectively overcome this defect, and it can overflow from the dam top for a long time with large flow, forming a waterfall effect.
IV. Safety and reliability analysis
Rubber dam usually needs to build gas supply station or water pump house, with many and complicated pipelines, while steel dam gate is only equipped with two integrated hoists. This type of hoist is a new type of hoist with simple structure and convenient operation, and does not need auxiliary facilities such as oil pipes and pumping stations. In addition, the crane is equipped with a manual device. If it can be operated manually due to power failure or other faults, it can be operated manually with only 5kg of operating force. This can effectively ensure that the dam can collapse and stand, which is extremely safe.
Rubber dams are generally difficult to achieve centralized network control, while steel gates (dams) can achieve advanced automatic control, and network control can be controlled on any internet in the world.
Five, the problem of freezing in winter
According to "Design Code" and actual use, once the rubber dam freezes in winter, it must be scraped off, otherwise it will cause fatal damage to the quality of the rubber dam. It is time-consuming and laborious, and it will bring great inconvenience to management. When it thaws in spring, the ice can't overflow the rubber dam, and the solid and sharp ice is likely to cut the rubber dam. Steel dams can spend the winter easily and safely. Generally, the steel dam is several tens centimeters higher than the water level, so in winter, the steel dam is inclined at a certain angle. If it freezes, the ice layer can extend upward along the inclined angle, thus effectively releasing the expansion force of hydrolyzed ice, so that the steel dam will not be damaged, which is equivalent to the normal riverside parapet. In addition, due to the hard characteristics of steel itself, flood discharge can be carried out at the dam top every spring.
Anticorrosion of intransitive verbs
The surface of steel dam gate is thermally sprayed with zinc according to the Standard Specification for Manufacturing Steel Gate of Water Resources and Hydropower, which has strong adhesion. The research results of authoritative organizations show that the velocity of sand ≤8m/s will not destroy the zinc layer. It is understood that the velocity of general rivers cannot reach this velocity.
Seven, siltation problem
Steel dam gate is a kind of gate with special structure. It has no bottom door slot and side door slot, and the door leaves are placed around the bottom shaft. The upstream water stop is pressed on the round shaft, and when the door is erected or dropped, the water stop does not leave the surface of the round shaft, and it always maintains a sealed water stop state; Based on the same principle of side water stop, the water stop surface never leaves the side breast wall (stainless steel embedded parts), so the silt (mud) will not affect the opening and closing of the steel dam gate.
For areas with serious siltation, sand (mud) retaining sill and bell mouth are generally set in front of the sluice. One is to effectively block large stones, and the other is to increase the velocity at the gate when the dam breaks the flood, which can effectively make the mixture of sediment and water directly rush downstream with the flood.
Generally speaking, the main function of sluice is to erect a dam to store water in the northern region. It is easy to deposit when the dam is erected for a long time, but the steel dam gate is dumped downstream around the bottom axis, so the deposited sediment is washed downstream by the water flow when the dam breaks, and it is impossible to form a blockage. In addition, after the flood discharge, we will analyze how much sediment (mud) there is according to the local sediment content, and calculate the opening and closing force needed when opening the gate through the sediment (mud) amount, and fully consider the force to overcome the sediment (mud) when opening the gate.
Eight. Energy consumption comparison
100m The power load of rubber dam needs at least 100kw/ hour, and the secondary dam lifting time is about 2-3 hours.
The gate of 100m steel dam only needs four hydraulic hoists, and the rated maximum power of each hydraulic hoist is 15kw. In this way, the power load of 100m steel dam gate only needs about 60kw/ hour. The dam lifting time is about 2-3 minutes each time.
Compared with rubber dams, steel dams save considerable power consumption every year.