Research Of Bored Pile Vertical Carrying Capacity In Permafrost Region

The distribution of permafrost in China is the third largest in the world and about 22 percent of the country are occupied by the permafrost. The environment in permafrost region is inconvenience for bridge engineering, the soil swell seriously for sake of long term low temperature in the permafrost area and subside greatly in case of the temperature rise beyond zero. Accordingly, bridge substructure in the permafrost area are usually destroyed by the abominable environment. Traffic transport in permafrost area is seriously influenced by the deformed bridge engineering. Bored pile, as a main form of bridge substructure, is also widely used in the permafrost area. Therefore, it is imperative to research the bored pile vertical bearing capacity in permafrost area. This thesis presents the research status in quo and development direction of the interaction of pile foundation in permafrost and single pile load transfer. The permafrost engineering characteristic and the theoretical analysis method of single pile load transfer are systemic introduced and the compute method of single pile vertical bearing capacity is summarized in this thesis. On the basis of the research method and results of the interaction of pile and soil currently, combined with the special characteristics of permafrost, a finite element model is created by means of ANSYS. On the basis of the finite element model, this thesis mainly consummate three aspects of works. In the first place, the result of finite element model created by ANSYS is verified by the single pile experiment in KunLunShan permafrost zone. The stress and strain status in pile and soil is analyzed through the finite element model, the finite element method used in the interaction of pile and soil is testified accurate and credible. In the second place, this thesis researches the influence of single pile load and displacement curve brought by the change of contact element parameter and soil parameter simulated by D-P material in ANSYS. The research can be contributed to select the appropriate value of parameter in finite element model. At last, it is well known that single pile load and displacement curve manifest the mechanical character of pile. In order to reasonably design the pile foundation in permafrost area, the influence of load and displacement curve, brought by the change of pile's length and radius, is researched in this thesis. The research result will be very useful to permafrost area pile foundation design.