Application Research Of New Bored Micro Pile Foundation For Transmission Line

With the accelerating development of tower foundation in China's power industry,there is an urgent need to develop a new type of foundation that is more suitable for transmission lines.At present,cast-in-place pile foundation is often used in overhead transmission lines in weak foundation or high groundwater level areas.The construction method of this foundation is traditional,and the construction process is not conducive to environmental protection,the cost is high.For traffic inconvenience,it is difficult for cast-in-place pile pore-forming machinery to enter the construction site and the construction is difficult.A new type of bored micro-pile tower foundation is a new type of environmental protection foundation which can be used in transmission line engineering on soft soil foundation under this background.In this paper,the finite element numerical simulation method is used to carry out the research on the new type of bored micro-pile.By establishing a three-dimensional pile-soil model and changing the values of pile and soil parameters,the bearing capacity of the new type of bored micro-pile is obtained.On the basis of the finite element method,by comparing the simulation results with the theoretical analysis,the mechanical mechanism,failure mode and influencing factors are studied.The specific work is as follows:(1)The single pile and group pile models are established by using the ABAQUS finite element software,the constitutive relationship of soil mass,the selection of friction coefficient between pile and soil,boundary conditions,and how to balance the ground stress are comprehensively analyzed,and the working mechanism of pile foundation is obtained by applying incremental load or calculating the reaction force by applying displacement.(2)Through the simulation analysis of single pile and group pile,the reasonable length-to-thin ratio of single pile,the inclination Angle of pile body,and the appropriate pile spacing between piles in the group pile are obtained.At the same time,it is concluded that the new bored miniature pile group foundation with inclined piles has better uplift bearing capacity.(3)Through the analysis of soil layer parameters,it can be found that the friction coefficient between pile and soil,pile elastic modulus,soil elastic modulus have great influence on the uplift bearing capacity of foundation.(4)The construction methods and modes of traditional micro-pile and cast-in-place pile foundations in China are compared and analyzed,and the construction technology suitable for new-type bored micro-pile is summarized.The economic comparison between the new-type bored micro-pile foundation and the cast-in-place pile foundation currently used in transmission lines shows that the new-type bored micro-pile has obvious economic advantages.