Development Mechanism Research On Vertical Compressive Bearing Capacity Of Pile-tip Post-grouting Plie

With the rapid development of high-rise building and huge structures, filling pile has been applied widely for its advantages such as none vibration, none soil-squeezing, applicable pile length and diameter, high bearing capacity and so on. However, the defects of filling pile, collapse of the hole wall and mud layer by the side of pile, will affect the quality and reduce loading capacity. Post-grouting technology on filling pile tip by applying high pressure slurry, penetrating, compacting, splitting soil and mud surface, enhance the strength of the pile and the pile side of the bottom soil, makes up for pile defects and improve ultimate bearing capacity of the pile and reduce the pile settlement. Currently, there is still lack of in-depth theoretical and practical understanding of post Grouting mechanism of carrying capacity, and theoretical research is behind the study of engineering practice. This paper model illustrates in-depth and systematic research and comet to valuable conclusions by model tests and numerical simulation for grouting pile vertical bearing behavior. The main contents are as follows:Designed model test and build the responding models. From single pile models of ordinary piles and pile after pile grouting, studied pile bearing capacity mechanism under vertical loads pile, summarized trends of pile top settlement, pile lateral friction, axial force, pile tip variation of resistance, researched of vertical bearing capacity mechanism of the post-grouting pile. The test results show that:post-grouting pile can effectively control pile top settlement, the ultimate bearing capacity almost doubled; post-grouting can improve lateral friction, to certain extent eliminate negative friction resistance; ordinary pile prone to have piercing destruction in sand foundation more than grouting pile; two kinds of pile lateral friction and end resistance happens in different order.Used the finite element calculation software ABAQUS, established a pile-soil axisymmetric model, and numerical simulation analysis were carried out from the model tests. The results show that:the calculation results are consistent with the experimental results on the pile settlement and axial force variation, indicating that the software in the appropriate choice of parameters and constitutive relation, the finite element method can be effectively used for pile bearing capacity characterization. This study analyzed two pile styles after pile of soil under different load shear and displacement field changes, and proved post-grouting pile could effectively improve soil failure modes and the bearing capacity.