On the issue of pile position deviation in pile foundation construction

Code for Acceptance of Construction Quality of Building Foundation Engineering GB 50202—2002 5.1.3 Driving (pressing) in piles (precast concrete square piles, prestressed pipe piles made by pretensioning). The pile position deviation of steel piles must comply with the requirements specified in Table 5.1.3. The deviation in the inclination of the inclined pile shall not exceed 15% of the tangent value of the inclination angle (the inclination angle is the angle between the longitudinal center line of the pile and the vertical line). Allowable deviation of precast pile (steel pile) positions (mm) Table 5.1.3 Item Permissible deviation (mm) 1 Piles with foundation beams: (1) Perpendicular to the center line of the foundation beam: 100 + 0.01H (2) Along the center line of the foundation beam: 150 + 0.01H 2 Piles in a pile foundation with 1–3 piles: 100 3 Piles in a pile foundation with 4–16 piles: 1/2 of the pile diameter or side length 4 Piles in a pile foundation with more than 16 piles: (1) Outermost piles: 1/3 of the pile diameter or side length (2) Intermediate piles: 1/2 of the pile diameter or side length Note: H is the distance between the ground level at the construction site and the designed top elevation of the pile. Given the situation described by the poster, a fill sand foundation constitutes a weak foundation (especially silt), which can very easily lead to horizontal displacement of the foundation piles. 1. Piling construction should be carried out after primary consolidation is completed as a result of preloading (it’s difficult to determine the extent of secondary consolidation); otherwise, the positions of the piles determined will be meaningless, as they keep changing. 2. Even after preloading is completed, pile driving will generate excess pore water pressure, and there is a process of dissipation (it is recommended that this take 7 days to 14 days for sandy soils, and 14 days to 21 days for clayey soils). This process can also cause ground settlement or displacement of the piles; this is a qualitative understanding. Quantitative analysis is less reliable; it relies heavily on experience. It’s best to first conduct experiments with a small number of piles in a limited area to determine whether the chosen site and time intervals are suitable, before proceeding with larger-scale implementation. Last edited by tpjj on 2009-2-13 11:15.]