Preliminary Feasibility Studies And Analysis On Method Of Virtual Pile Of Soil

Method of virtual pile of soil is a new method to solve the interaction between pile and the soil under the pile. In this method, the soil between pile tip and bedrock is taken as a virtual pile to study the dynamic soil-pile interaction problem. Then the interaction between soil and pile, non-homogeneity or stratification of the soil, depth of the bedrock and settlement of pile over time can be taken into consideration in analysis of pile dynamic or static characteristics. Therefore, method of virtual pile of soil has broad prospects for application.This thesis which is based on the method of virtual pile of soil has done the main original work as follows:1. The static equilibrium equations of soil and virtual pile are solved according to the boundary condition and the stress and displacement fields of elastic soil under a rigid circular plate are investigated. The vertical stress and displacement along the center line of the virtual pile and at various depths is investigated and the stiffness at the top of virtual pile is studied. Some main influencing factors, such as the length of virtual pile, Poisson's ratio, modulus of soil are analyzed to illustrate the distribution of vertical stress and displacement. Meanwhile, the results are compared with other existing researches to illustrate the applicability of the virtual pile of soil method.2. According to the dynamic equilibrium equations of soil and virtual pile, dynamic characteristics of hysteretic damping soil under a rigid circular plate at the harmonic load are investigated. The influence on the resistance factor and vibration modes of soil, curves of settlement-frequency, complex stiffness-frequency and mobility wave-frequency of virtual pile caused by length of virtual pile, Poisson's ratio and hysteretic damping ratio is discussed. And the relationship of complex stiffness and frequency is compared with other existing researches. 3. Firstly, according to the static equilibrium equations of pile and virtual pile and the consistency conditions at the interface, the analytic solution of single pile settlement based on the load transfer method is yielded. Secondly, using the elastic theory method based on Mindlin's displacement solution, the analytic solution of single pile settlement is obtained when the interaction of the shear stress along the pile and the virtual pile is considered. Thirdly, combining the static equilibrium of soil, pile and virtual pile with the boundary and consistency conditions, the analytic solution of the settlement at the pile top is obtained. Finally, influencing factors, such as length of pile and virtual pile, modulus of pile and soil are analyzed and the load-settlement curves of the three methods above are compared. Meanwhile, the results are compared with other existing researches to illustrate the feasibility of virtual pile of soil method.The preliminary feasibility studies and analysis in this thesis will promote the development of researches in the static and dynamic characteristics of piles using virtual pile of soil method.