Research on Bearing Capacity of Post-grouting Super-long Bored Pile

Abstract

The bearing capacity of the post-grouting super-long bored pile, calculated by the standard enhancement coefficient, is 66% larger than that of the measured. The FEM analysis shows that when the grouting radius at the pile end is 1.5 d and the permeating height of the cement slurry is 4.05 m from the pile end, the end resistance enhancement coefficient is 1.17, and the pile side average friction resistance enhancement coefficient is 1.31 within 12 m above the pile end. The calculated bearing capacity is close to the measured bearing capacity of the post-grouting pile by those enhancement coefficients. The calculation shows that: a) in the case of no grouting, the pile end reaction force is about 5.78% of the pile top load; b) in the case of grouting, when the grouting diffusion radius at the pile end is 1.5 d and the permeating height from the pile end is 4.05 m, the post-grouting pile end reaction force is about 6.78% of the pile top load; and c) after grouting, the load transmitted to the pile end cannot be significantly increased; d) using the reinforcement coefficient suggested by the Standard, the calculated bearing capacity is larger than the measured.