Study On Dynamic Response Of Poroelastic Soil Medium Subjecting To A Moving Load Based On Nonlocal Biot Theory

In recent years,with the rapid development of high-speed railway,the impacts of underground foundation on the power of the entire system and environment have become increasingly prominent.Many scholars use the classic Biot theory to study the dynamic response of the foundation caused by train operation,but the classical Biot theory only uses porosity as a factor affecting the mechanical properties of saturated porous media.Therefore,based on the nonlocal Biot theory which considering the influence of pore size and pore dynamic stress,the following researches are carried out on the propagation characteristic of surface wave generated by moving load and the dynamic responses of saturated poroelastic medium under moving load.The propagation characteristic of surface wave generated by moving load in saturated poroelastic medium has been studied.The effects of nonlocal parameter on the propagation characteristic and attenuation characteristic of Rayleigh wave in saturated poroelastic medium have been analyzed in detail.The results showed that the influence of non-local parameter on the Rayleigh wave velocity and displacement field becomes stronger with the frequency increases.The nonlocal parameter does not have significant influence on the energy distribution and most of the Rayleigh wave energy is contributed by the shear wave.The dynamic response of poroelastic soil medium subjecting to a moving point load based on nonlocal Biot theory has been solved by the Fourier transform and inverse Fourier transform.The influences of nonlocal parameter and load moving speed on the displacement field both in wave number domain and space domain have been analyzed in detail.The effects of nonlocal parameter on the pore pressure as well as the permeability have been presented.The results showed that the influence of nonlocal parameter on thedisplacement field became stronger with the wave number and the load moving speed increased.The nonlocal parameter has a significant influence on the pore water pressure while the load moving speed is high.Using Fourier transform and inverse Fourier transform,the dynamic response of a cylindrical structure embedded in saturated poroelastic medium subjected to a moving ring load has been investigated theoretically based on nonlocal Biot theory.The influences of nonlocal parameter,load moving speed and load self-vibration frequency on the displacement field have been analyzed in detail.The results showed that the influence range of the nonlocal parameter is concentrated within the vicinity of the point that the load applied.The influence of nonlocal parameter on thedisplacement field became stronger with the load moving speed and the load self-vibration frequency increased.Based on Fourier series expansion and Fourier transform method,the dynamic response of poroelastic soil medium subjecting to a moving rectangular load has been studied.The variation of displacement response versus load moving speed and load selfvibration frequency for different modes indicated that the influence of nonlocal parameter on the displacement field can be ignored in low mode,and the displacement response mainly depends on the low mode.