Study On Torsional Vibration Of Pipe Piles In Single-phase And Saturated Transversely Isotropic Soil

Based on the continuous medium model considering the interaction between pile and soil,the torsional vibration of transversely isotropic soil is studied in the frequency domain,and the effect of partial soil the torsional vibration of some exposed concrete piles in the single-phase transversely isotropic soil is studied.Finally,the influence of the main geometrical parameters and physical parameters on the complex stiffness of the pile top is analyzed.The main work is as follows:Firstly,the pile soil and pile core soil are regarded as single-phase transversely isotropic soils.Considering the torsional vibration of pile-soil coupling,the general equation of soil and the equation of torsional vibration of pile are established.Combining boundary conditions,the analytical solution of the torsional vibration displacement of the soil and the response of the torsional frequency response of the pile is obtained by the separation variable method,and the expression of the reciprocating stiffness of the pile top is obtained.The influence of the main pile-soil parameters on the torsion complex stiffness of the pile top is analyzed by numerical examples.The results show that the anisotropy parameters of the pile soil have a significant effect on the dynamic stiffness of the pile top.The amplitude of the stiffness and damping is significantly reduced with the increase of the anisotropy parameter,but the impact is smaller than the pile soil.Secondly,considering the partial soil effect and the transversely isotropic nature of the soil,the torsional vibration of some exposed pipe piles is studied.Ignoring the other displacement of the single-phase soil layer and the radial displacement of the single-phase soil layer of the pile core,and finally obtained the torsional complex stiffness of the pile foundation.The numerical examples show that the anisotropic parameters of the pile soil have a significant effect on the reciprocating stiffness of the pile top.The influence law of the anisotropy parameters of the pile core soil is similar to that of the pile soil,but the influence degree is smaller than that of the pile the magnitude of the shock and stiffness increases with the shear modulus of the pile.As the inner and outer diameter of the increasing stiffness and damping the amplitude of the shock increases,high frequency stiffness and damping amplitude of the shock are larger.It canbe seen that the inner wall of the pipe pile should not be too thin,the pile core buried in the soil part to ensure a certain length,especially in the high frequency range,in order to ensure the safety of the actual project.Finally,based on the theory of Biot saturated soil,considering the transversely isotropic characteristics and axial symmetry of pile surrounding soil and pile core soil,the dynamic equilibrium equation of transversely isotropic saturated soil and the basis of fluid balance equation In this paper,the analytic solution of the torsional vibration of the pile at the end of the pile is obtained by considering the radial displacement of the piles and the pile.Combined with numerical examples,the influence of them on the torsional vibration of transversal isotropic saturated soils is observed by changing the main pile parameters.The results show that the torsional vibration of the pipe pile in the saturated transversely isotropic soil also has resonance phenomenon.The larger the anisotropy degrees of the saturated soil in the pile,the greater the stiffness of the pile top.When the frequency is large,the influence of the mechanical factors such as the anisotropy degree and the shear modulus of the saturated soil on the torsional vibration of the piles in the transversely isotropic saturated soils are bigger.