Driven by economic development, there are higher requirements for water conservancy and hydropower construction. Considering its particularity, we must proceed from the specific situation and do a good job in construction. As an important infrastructure, water conservancy project involves flood control, irrigation, water transportation and starting point. In order to ensure the building quality, it must be carried out according to the corresponding building grade in terms of function and function, so as to ensure the building quality and enhance the architectural advantage.
1 project overview
This study is based on a project in Hunan. The water conservancy project is located near the upper reaches of the river and undertakes the tasks of flood control, moisture prevention and irrigation. In the process of planning and designing the project, it is necessary to define the grade according to the specific situation. The grade of sluice project and foundation building is 1, and the grade of temporary building is 4.
The project site belongs to soft soil foundation. In order to ensure the construction quality and improve the stability and safety of water conservancy projects, it is necessary to adopt steel sheet pile cofferdam construction technology and carry out structural construction reasonably.
2 Application of steel sheet pile cofferdam construction technology in water conservancy projects
There are many factors that affect the construction technology of steel sheet pile cofferdam. According to its particularity, it is necessary to do a good job of technical analysis in clinical research and carry out it according to the application requirements. Let's analyze the application of steel sheet pile cofferdam construction technology in water conservancy projects.
2. 1 Determine the construction process
The construction process of steel sheet pile cofferdam is special, which is divided into foundation leveling, steel sheet pile sinking and cofferdam closure. , according to the requirements of the application process. In addition, in the management stage, do a good job in management to reduce potential safety hazards, and then improve the construction quality.
2.2 steel sheet pile construction
In the whole construction process, the construction of steel sheet pile is the key and difficult point. In the actual operation stage, it is necessary to transport the prepared steel formwork to the corresponding construction platform, and use professional hoisting equipment to splice them piece by piece. After the last lap of splicing is completed, the pile will be controlled according to the specific situation, and the pile will sink by its own weight. When it sinks to the bottom of the water, start the small vibrating hammer to make it sink gradually. In this process, water is pumped into the cofferdam to ensure the smooth construction. In order to improve the construction stability, the steel sheet pile stopped sinking after sinking into the soil layer, and the pile body was adjusted and improved.
After the sinking operation technology, the outside is surrounded by clay woven bags, and stones with a thickness of about 50cm are placed inside. After the construction, pump water, analyze and check the leakage of cofferdam in time. If there is leakage or other phenomena, it should be treated as soon as possible to avoid serious deposition. In addition, the underwater geological conditions need to be investigated and analyzed in detail. In the process of construction, auxiliary high-pressure flushing or vibration can be used to avoid the hard driving and loss of steel sheet piles.
2.3 Cofferdam Closure Construction
At the stage of cofferdam closure construction, there are certain requirements for the specifications of steel sheet piles, and the closure degree directly affects the sealing performance of cofferdam. In the subsequent construction stage, taking splicing construction as an example, it is necessary to measure the actual width of steel sheet piles in advance. Usually, if the side ports at both ends are difficult to match, corresponding measures need to be taken to adjust. In the initial splicing stage, the corresponding model should be set in time to predict the final situation. The width of steel sheet piles can be determined by measuring the closing length, and steel sheet piles can be manufactured and assembled according to this standard.
If it is found that it is difficult to completely close the steel sheet pile, it is necessary to hang the steel sheet pile, arrange professionals to set it up, and make appropriate adjustments when necessary. In addition, due to the influence of other factors, the pile body and the interface will not be parallel, so it needs to be adjusted by external force to ensure that the steel sheet pile is consistent with the closure. The construction stage is affected by internal and external factors. If the steel sheet pile is exposed, in order to avoid being hammered, the pulley block should be properly adjusted and the corresponding composite pulley should be installed to ensure that the other end also falls.
The position of steel sheet pile cofferdam will be uneven, and the construction personnel have to measure the position of long-distance steel sheet pile, but there are corresponding risks in this way. Because of the large gap, the pressure on the steel sheet pile will also increase, so another treatment method can be adopted according to the specific situation. In the stage of measuring the last group of steel plates, it is necessary to correct the steel sheet piles to improve the sealing performance and avoid serious leakage.
2.4 Demolition of steel sheet piles
Before the steel sheet pile is pulled out, the supporting equipment in the cofferdam should be removed and measured according to the irrigation density. Select Group B or steel sheet piles that are relatively easy to be dismantled downstream, and measure them in combination with the elevation of steel sheet piles. Usually the height is about 1~2m. After loosening, it is pulled out from downstream to both sides, and the deformed pile tip is used to construct the pile foundation, which can increase the capacity of the pile pulling equipment and pull out the corresponding piles together.
In the pull-out stage, it is necessary to cut off the welded steel sheet piles and planks, and set the water level around 1~ 1.5 in the cofferdam area, as shown in figure 1.
In the process of handling, we should be kind, handle with care, and avoid too many collisions directly affecting the cofferdam template. The splicing needs to be well connected, the sealing piece needs to be plugged, the welding must be firm and reliable, the bolt connection should be checked in advance, and the specific soil conditions should be observed after sinking into a specific position. If it is found that the lower part of the cofferdam is not in conformity with the design, it should be reported in time and effective measures should be taken.
3 How to improve the construction quality
3. 1 Grasp the construction requirements
In view of the special requirements of water conservancy project construction, it is necessary to analyze the cofferdam construction technology in practical stage. Considering the specific changes of construction technology and properties, it can be carried out according to the technological requirements to avoid adverse effects. In the operation stage, the staff should pay attention to ensure the safety of electricity consumption and observe the specific situation around the cofferdam. If deformation or other conditions are found, they should immediately communicate with the project department and deal with them in time to avoid improper construction.
3.2 Conduct on-site guidance
During the cofferdam construction, the leaders should give on-site guidance. In order to avoid illegal operation or other unexpected situations, standardized construction can be carried out according to specific conditions to meet the requirements of subsequent construction. It is necessary to set a water level marker on the cofferdam to observe the water level change in time. If under the overall conditions, construction can be carried out. If there is any abnormal phenomenon, the construction should be stopped immediately to nip in the bud. Do a good job of cofferdam reinforcement and heightening in rainy season to ensure technical implementation.
4 conclusion
In view of the specific situation of water conservancy construction, we should proceed from the specific situation in practice, do a good job in basic guidance and carry out it according to the construction requirements. Because of the special construction process, the staff should pay attention if there are unexpected situations or other phenomena. Starting from the present situation, innovative construction methods are adopted to improve the stability and safety of construction and ensure the safety of cofferdam construction.
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