Research On The Compacting Effects And Settlement Analysis Of Y-shaped Tube-sinking Cast-in-situ Pile

The Y-shaped tube-sinking cast-in-situ pile can exert the potential capacity both of pile and soil more than the traditional tube-sinking cast-in-situ pile of round cross-section. Therefore, it's a new foundation treatment worth to extend.As the Y-shaped pile is a new technique, the research in this area is just at the starting phase. This paper aims at the research of its construction technics, technical characteristics, the mechanism to reinforce the foundation, compacting effects and settlement calculation by theoretical analysis and field test. The primary contents are as follows:1. The construction technics and some other characteristics of Y-shaped pile are introduced, such as technical properties, the quality inspection and control, the economic comparison with other piles. The field test where Y-shaped pile is used to treat the soft soil foundation of a highway is also introduced.2. The field test of the compacting effects of Y-shaped pile is operated. In the test the soil displacement, stress change and pore water pressure are observed and also analyzed.3. Based on the theory of Sagaseta the displacement by pile sinking can be obtained. The soil surface heave caused by sinking of group-piles with Y-shaped cross-section, round cross-section and square cross-section is compared. Considering the horizontal limit equilibrium state of soil when pile sinking and the cavity expansion theory, the soil stress change and the pore water pressure can also be obtained.4. The soil subsidiary stress caused by load of Y-shaped pile is discussed. And the settlement calculation method of Y-shaped pile composite foundation is improved.