Technical analysis of dam construction of hydropower station?

What does the technical analysis of dam construction of hydropower station specifically include? The following Zhong Da consults the bidding teacher to answer your questions for your reference.

China has a vast territory and many rivers, especially in recent years, droughts and floods have occurred frequently, and some cities are seriously short of water. The distribution of water resources in China is uneven. In this case, the construction of hydropower dams in the western region where water resources are scarce may realize the effective regulation and rational utilization of water resources, which will play a positive role in the occurrence of droughts and floods in the downstream areas, not only providing renewable resources for China's social and economic development, but also playing an extremely important role in improving the power quality of hydropower stations.

1 characteristics of dam engineering of hydropower station

In recent years, the characteristics of hydropower dam projects in China have also been highlighted, and the specific characteristics in construction are roughly as follows:

First of all, the dam project of hydropower station has a large amount of work and a long construction period, and it will inevitably go through two main flood seasons during the construction process, so it is necessary to make good preparations for the flood season during the construction process.

Secondly, due to the long construction period, winter construction may be encountered during the construction process, and preparations for winter construction need to be made.

Thirdly, many materials need to be used in the construction process, among which fine stone concrete masonry, impervious panel, overflow concrete, sand, stone, cement, steel bar and other components are more.

Finally, in the construction process, because the dam is tall, wide and the water discharge tower is high, various safety protection measures need to be taken in the construction process.

2 hydropower station dam construction technology

2. 1 Diversion construction method

One is to adapt to the flood, topographic and geological conditions in the dam site area, the main project design scheme, the construction period and the construction conditions of the cofferdam itself. The second is to meet the requirements of resettlement at different stages, such as dam closure, flood control and water storage, yard review and preparation of building materials, and complete temporary construction of wind, water, electricity, roads and houses. The third is to adapt to the approach of construction team, construction machinery, feeding and rolling test, grading test of sand and gravel mining, and mining scheme of quarry. The fourth is to adapt to many external conditions such as blasting test. Reasonable diversion schemes must be carefully compared and analyzed.

2.2 Earthwork excavation construction

2.2. 1 excavation construction technology. Construction technology of earthwork excavation: measures such as top-down excavation layer by layer are adopted to control the total amount and thickness of earthwork excavation, and mechanical operations such as excavators and loaders are adopted to ensure that the excavation construction meets the requirements of specifications. In addition, the elevation of subgrade top surface for earthwork excavation should be strictly controlled to meet the requirements of design elevation.

2.2.2 Excavation quality and safety measures. First, establish and improve the construction quality management system and the quality self-inspection system of "horizontal to edge, vertical to bottom and effective control", and strictly implement the systems of self-inspection, mutual inspection and handover inspection. Second, in strict accordance with the construction technical regulations, strictly implement the construction technical specifications, technical standards and related operating specifications. Third, control the elevation of the top surface of subgrade and the straightness of slope during earthwork excavation, keep the top surface of subgrade flat and accurate, and ensure the straight and beautiful slope of subgrade.

2.3 concrete engineering construction

2.3. 1 template installation

(1) template installation. Template installation should pay attention to: first, whether the bar is straight and whether the support is firm; The second is whether the rigidity, strength and stability of the bar meet the design requirements and whether there is deformation. In order to facilitate formwork removal, the release agent should be evenly coated on the surface of the formwork in contact with concrete. When removing the formwork, ensure that the non-bearing formwork and its surface edges and corners are not damaged, while the relatively bearing formwork can only be removed when the concrete has enough strength to bear its own weight and other loads. Dismantling sequence: first dismantle and then brace, first dismantle and then brace; Dismantle the non-bearing part first, and then dismantle the bearing part.

(2) steel formwork for corridor top arch. The steel formwork of the top arch of the corridor is composed of steel arch and variable arc steel plate, which are connected by U-shaped clips, and the panel and arch are connected and fixed by special semicircular hooks. The steel formwork of the top arch of the corridor is supported and fixed by the supporting piles on the upper wall of the side wall of the corridor, and no additional top bracing is needed. The technical points of the steel formwork for the top arch of the corridor are as follows: first, the steel arch erection of the formwork is designed as a semicircle, which can be directly supported by the supporting piles on the side wall of the corridor; Second, the radian of the steel formwork panel can be adjusted to meet the needs of the top arch vertical formwork in corridors with different sections; Third, it can pass freely in the corridor during construction, with less wood consumption and convenient construction.

2.3.2 Reinforcement connection technology

At present, in the process of dam concrete construction of hydropower station, the mechanical connection technology of steel bars is usually used, and some of them are used in construction. The mechanical connection technology of steel bars is mainly connected by sleeve joints such as extrusion, taper thread, straight thread and molten metal filling, and various joints such as plane joints of compressed steel bars, which plays an extremely important role in improving construction efficiency. At present, in order to effectively improve the working efficiency on site, some individual projects adopt mechanical connection technologies such as cold extrusion, hot upsetting and equal strength flow rolling straight threads, which not only effectively reduces the labor intensity, but also plays an extremely important role in improving the working environment and improving the quality of steel bar connection.

2.3.3 Concrete pouring construction technology

In the concrete construction of dam project, concrete mixing must be carried out according to the actual needs of the project and the specific requirements of the construction, and the uniform mixing must be ensured within the specified mixing time. Concrete is transported by car or vertically, and the slump of concrete is controlled during transportation. In the process of pouring, concrete should be poured in layers and blocks, from low to high. During pouring, the concrete entering the warehouse shall be closed with pouring to avoid accumulation, and no water shall be sprayed in the warehouse.

2.3.4 concrete construction of overflow plate

In the concrete construction of overflow dam face slab, there are high requirements for its surface, not only to ensure the smoothness of the surface, but also to have high requirements for its wear resistance. Before construction, the construction scheme and template design must be done well. In order to facilitate formwork installation, it is necessary to open holes on both sides of channel steel corresponding to steel formwork holes, so as to carry out formwork construction at the same time. At the same time, after the template hole is aligned with the opening of channel steel guide rail, it is necessary to effectively reinforce the template. The formwork needs to be removed before the initial setting of concrete, and the concrete surface needs to be polished with a steel knife after formwork removal, which not only effectively ensures the smoothness of the concrete surface, but also ensures the smoothness of the concrete surface.

2.4 Dam masonry construction

First, try to set the stone before laying, so that its size matches, the bedding face is flat, the exposed surface is flush, the oblique mouth is inward, the mortar joint is filled with mortar, and the large stone joint is filled with mortar before gravel, and the width is controlled at about 2 cm ~ 3 cm. Second, when laying, the upper and lower stones are staggered, and the inside and outside are staggered to prevent heavy joints, dry joints and empty joints. 3. The spacing between layers is about 1m, and the upper and lower layers are staggered by pulling stones. Fourthly, expansion joints and buried drainage pipes are needed in masonry construction. Fifth, after the masonry is completed, cover it with sacks and spray water for maintenance to ensure the surface moisture.

2.5 joint surface prevention

During the concrete pouring construction of the dam, there is a lot of concrete bleeding, and the bleeding and laitance will flow to the bottom of the pit along the inclined plane of the concrete, and then be discharged to the outside of the foundation pit through the collecting well. In the process of concrete pouring, when it reaches a certain elevation, cement mortar will accumulate on the surface of concrete due to massive pumping of concrete. In order to effectively prevent cracks, wooden crabs need to be used for leveling. In order to effectively prevent the concrete surface from cracking, it is necessary to calender the concrete surface with iron plate before the initial setting of concrete, so as to enhance the waterproof and crack resistance of the concrete surface.

3 Conclusion

In recent years, there are more and more dam construction projects of hydropower stations, and each project has its own characteristics. Therefore, we must do a good job of diversion according to the actual situation of the dam project, ensure the feasibility of the construction technical scheme, and constantly improve various technologies and construction links in the construction to achieve effective control of the dam construction quality.

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