1 basic form
Typical engineering piles are pre drilled ground anchor piles, with a length of 1.6m. The upper section of the pile body is a steel pipe with an outer diameter of about 76mm, with a length of 700~800mm and a thickness of 3~4mm. It is hollow, and the top of the pile body is provided with a fixed hole and a pair of holes connected with the support; The lower section of the pile body is welded with steel bars and steel pipes; The average thickness of galvanized layer of metal components shall be greater than 55um.
2 features
1) Project cost. The steel structure of the pre formed hole anchor pile is prefabricated in the factory to ensure the quality. Cancel the on-site reinforcement cage manufacturing process, save costs, and the economic benefits figure 8-9 pre formed hole ground anchor pile foundation structure is obvious.
2) Shorten the construction period. Compared with the traditional independent foundation and strip foundation, the construction of pre formed hole ground anchor pile foundation is convenient and fast, and can shorten the construction period.
3) Protect the environment. Bored cast-in-place steel pipe pile foundation can minimize earth excavation and backfilling, and minimize damage to the environment.
4) The drilling diameter is small. Compared with the bored hole with a diameter of not less than 250mm for the cast-in-place pile, the bored hole diameter of 150~180mm for the pre drilled anchor pile can be used in the bedrock area.
5) The requirement for slump is very high. The collapse is too small, affecting the pumping efficiency and even blocking the pipe; If the slump is too large, it is easy to separate and bleed.
8.5.1.3 scope of application
The pre formed hole ground anchor pile is applicable to gravel soil, weathered rock strata, and rock strata with complex geological conditions, many interlayer, uneven weathering, and large changes in soft and hard. It is applicable to the pile foundation construction of photovoltaic power station in mountainous geological conditions.
3 construction method
Figure 1-1 shows the construction process of steel pipe pile foundation.
Due to the limitation of geological conditions, there will be gaps around the foundation hole due to bit vibration and other reasons after drilling. In order to ensure full grouting, the first grouting and the second grouting need to be separated for a period of time, that is, the second grouting can be carried out after the surrounding gap is filled with mortar. Avoid the situation that there is vacuum in the concrete in the hole and the concrete pouring is not solid after the secondary grouting.
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