关键词: 扩孔灌浆管桩, 承载力, 灌浆, 桩-土共同作用机制

Abstract: Through the statistical analysis of the pipe piles’ vertical bearing capacity tests in the soft soil area, according to the pipe pile foundation which mainly bears vertical load, we can find that more than 70% of the pipe piles’ actually vertical bearing capacity were less than 50% of the ultimate strength; and it failed to get full use of the high material strength of the pipe pile. The purpose of this study is to improve the work process of the pipe pile, in order to improve its bearing capacity. By the method of prototype test, this paper presents a kind of enlarged grouting pipe pile patent which is suitable for soft soil area.We can set the endplate’s diameter greater than the pile’s diameter, which can form a space surrounding the pile larger than the pile’s diameter while the pile was sinking, and we can use cementitious materials, such as the surplus grout, to jet grout into that space; then reaming grouting pipe pile is formed. Through thirteen test piles’ vertical compression tests, tension tests, and horizontal force full scale tests, it is shown that this process significantly increased the resistance of the piles’ tips and the soil surrounding the piles; and in this way the pipe piles’ vertical bearing capacity and lateral stiffness can be improved. And this type of pile has been applied to a practical project, and good social and economic benefits are achieved.

Key words: pipe pile with enlarged diameter, bearing capacity, grouting, pile-soil interaction mechanism