Problems with floating piles caused by pressure application of prestressed pipe piles?

The problem of "floating pile" you mentioned is still relatively common in the construction of hydrostatic pipe piles, and we generally call it pile lifting, and the pile lifting is mainly static pile.

Generally speaking, the pile pressed after the pressure will squeeze the pile that has been pressed, especially the long pile for the short pile; This kind of raised pile is doing a static load test.

, the settlement begins to be larger, the curve is steeper, but when the pile tip reaches the bearing layer.

, the bearing capacity increases significantly, and the settlement curve tends to be flat, which is a typical curve of pile lifting. In addition to causing the static load settlement to be large, the pile welding joint may be broken, and once the pile body is lifted, the horizontal extrusion force of the pile will also increase accordingly, so that it is likely to cause the pile to tilt and deviate.

For the treatment of the problem of pile lifting, the first is to avoid, reasonable arrangement of pile pressing sequence before construction, the same single building generally requires the first pile of the site, and then the surrounding pile, the first deep pile, and then the shallow pile. For the pile that has been lifted, the method of recompression is generally adopted, but the foundation bearing the horizontal load should be cautious. Another method is the pilot hole, but I personally do not advocate using this method, because the pilot hole will lead to longer construction time and higher costs.

Hammered piles also have a squeezing effect, and the problem of lifting the pile body will also occur.

Hope it helps.

The one on the first floor was very detailed and studied.

1) The squeezing effect makes the pile top float. The soil body is compacted in the process of pile sinking, the porosity of the soil is reduced, the soil body is compacted in the horizontal direction, and then the soil body passively compacts or creeps upward, and the soil body is relatively reduced due to the vertical stress, causing the soil body to move upwards and the ground is uplifted, and the pile body is subjected to the upward friction force to make the pile body float. In addition, in saturated cohesive soil, the ultra-static pore water pressure generated by pile sinking and soil squeezing is also a reason for the pile body to float.

2) hammering method pile sinking pile top float than static pressure method obvious, when the hammer acts on the pile top, the pile top moves down, according to the stress wave theory, the pile body good socks produce a vertical stress wave, at this time the stress wave propagates to the pile around the pile through the soil around the pile, and at the same time, the soil around the pile also produces an upward stress wave, so that other adjacent piles are subjected to upward force and move. When the pile spacing is small, the buoyancy force generated by hammering the sinking pile on other piles is larger.

3) The rebound of the soil makes the pile top float. According to the design requirements, some pile top elevation is below the natural ground, for example: when the frame bridge base is reinforced with pipe piles, the pile top elevation is below the natural ground, the pipe pile needs to be sent to the ground below 5 6 meters deep by using the pile feeder, and after the foundation pit is excavated, the soil body rebounds due to the unloading of the base, causing the pile top to float.

Yes. The floating of high-strength prestressed pipe piles is easy to occur in construction, which not only affects the construction progress, but also affects the quality of the pile. As long as appropriate control measures are taken, it is possible to ensure the progress and quality of pile foundation works.

Due to the characteristics of high bearing capacity, low cost, strong adaptability and industrial production of pipe piles, high-strength prestressed concrete pipe tremor piles have been widely used in coastal soft soil areas. However, in the construction process of prestressed pipe pile, it is easy to float and affect the progress and quality of pile foundation engineering. In this paper, the cause of the floating is analyzed through the example of high-strength prestressed concrete pipe pile engineering, and the treatment measures and preventive measures are proposed.