Abstract: Based on the engineering background of a tall building at the center of Xi’an, the project uses the technology of post grouting bored pile foundation treatment. In construction, the vertical compressive static load with and without bored grouting pile; and pile body internal force are tested. This paper calculated the post-grouting pile's ultimate bearing capacity of pile foundation based on five methods, including the building pile foundation technical specification, lateral resistance and end resistance coefficient method, the ultimate bearing capacity enhancement coefficient method and improvement of the bearing capacity of pile. The results show that the ultimate bearing capacity of pile foundation increased by 24% with the methods of post-grouting pile; lateral resistance and end resistance coefficient method, and the ultimate bearing capacity enhancement coefficient method is closed to field measurement. Building pile foundation technical specification and the method of only considering the improvement of pile’s bearing capacity are largely different from the measured results, and the calculated value is conservative.

Key words: super highrise, foundation treatment, post grouting, bored pile, bearing characteristics