Steel pipe piles are commonly used components in bridge pile foundation construction. They have the advantages of high bearing capacity, flexible piling, and fast construction speed. Especially under complex terrain conditions, steel pipe piles show more significant advantages. The types and sizes of steel pipe piles are very rich and can be customized according to customer needs. The steel pipe piles produced in the market have various specifications. During construction, the most suitable application can be selected from a variety of specifications based on the actual stress conditions, so that the strength of the steel pipe piles can be fully utilized to meet the project's requirements for safety and economy.
Steel pipe piles are composed of steel pipes (such as seamless steel pipes, SSAW steel pipe, and LSAW steel pipes can all be used as steel pile pipes), tongue and groove, and tongue and groove pins. The left end of the steel pipe diameter is vertically connected to the tongue and groove wall. The cross section of the tongue and groove is a square frame with one side open. Reinforcement ribs are provided on the side of the tongue and groove. The right end of the steel pipe diameter is vertically connected to the tongue and groove pin at the radial position. The groove section of the tongue and groove pin is I-shaped.
For the convenience of transportation and limited by the height of the pile frame, steel pipe piles are usually composed of a soil section pile, a lower section pile and several middle section piles. The segment length of each section pile is generally not more than 2-15 meters, usually 13 meters or 15 meters. The end form of the steel pipe pile should be determined based on the comprehensive consideration of factors such as the soil layer to be traversed, the nature of the bearing layer at the pile end, the size of the pile and the soil squeezing effect. The lower end of the steel pipe pile can be divided into open and closed ends: the open pile end can be divided into two types: with reinforcement hoop and without reinforcement hoop; the closed pile end can be divided into flat bottom and cone bottom. In general, the upper, middle and lower sections of the steel pipe pile often use the same wall thickness, but sometimes in order to make the pile top withstand greater hammer stress and prevent radial instability, the wall thickness of the upper section pile can be appropriately increased, or a flat steel reinforcement hoop with a width of 200-300 mm and a thickness of 6-12 mm can be welded on the outer ring of the pile pipe. At the same time, in order to reduce the friction resistance of the pile pipe when it sinks and prevent the end from being damaged due to deformation when penetrating into the hard soil layer, a reinforced short section will be set at the lower end of the steel pipe pile.
What kind of steel pipe is generally used for the manufacture of steel pipe piles?
The pipe material of steel pipe piles is generally ordinary carbon steel, with a pile tensile strength of 402MPa and a yield strength of 235.2MPa, or selected according to design requirements. All materials must meet the design requirements and have a factory certificate and test report. On-site production of steel piles should have a flat site and wind and rain protection measures. Steel pile pipes generally use seamless steel pipes, welded spiral steel pipes and flat rolled steel pipes.
Steel pipe piles can be divided into seamless steel pipe piles and welded steel pipe piles according to the production method. Seamless steel pipe piles are rarely used due to their high cost; welded steel pipe piles are made by rolling steel plates into cylindrical shapes and welding. The production process is relatively simple, and the diameter and wall thickness can be selected at will. Compared with seamless steel pipes, the cost is lower, so it is the most commonly used type of steel pipe piles. Welded steel pipe piles are mostly welded by electric welding. According to the processing technology, there are two types of spiral seam welded steel pipes and straight seam steel pipes. Since spiral seam steel pipes have greater rigidity, they are more commonly used in engineering.
The length of the pile pipe is not limited by spiral welded steel pipes, and steel pipe piles of any length can be obtained. Steel strips of the same width can also be made into steel pipe piles of any outer diameter by adjusting the angle of the spiral roll. Since the strip steel is preformed at both ends, its dimensional accuracy, straightness and roundness can be high. This method can produce large-diameter pipes with an outer diameter of up to 2500 mm and a plate thickness of up to 25 mm.
Flat rolled steel pipes are slightly inferior to spiral welded pipes in production accuracy and production volume. When the number of steel pipe piles in the project is small and the production requirements are not high, this method can be used to make them on the construction site or in a simple house. The production process is: steel plate trimming, leveling, rolling pipe sections, pipe section welding, pipe end beveling, pipe section splicing and forming, welding quality inspection, appearance finishing, and delivery. By adjusting the position of the rollers, the pile pipe diameter and plate thickness can be unrestricted.
The quality of steel pipe piles is directly related to the safety and service life of the project. Therefore, each link needs to be strictly controlled during the manufacturing and installation of steel pipe piles. The material selection must meet the design requirements, and each process in the manufacturing process must be strictly inspected for quality. In particular, the inspection of welding quality, including the appearance inspection of the weld, non-destructive testing (such as ultrasonic testing and radiographic testing), etc., to ensure that the welding quality meets the design requirements.
Steel pipe piles play an important role in the construction of bridge pile foundations. Their high bearing capacity, flexible construction methods and fast construction speed make them an ideal choice for complex terrain conditions. By reasonably selecting the type and size of steel pipe piles and designing and constructing them in combination with actual stress conditions, the strength of steel pipe piles can be fully utilized to meet the requirements of safety and economy of the project. In the future, with the continuous development of science and technology and construction technology, steel pipe piles will show their unique advantages in more fields.