饱和土层中桩的扭转振动响应分析

基于饱和多孔介质理论研究了在三维轴对称条件下端承桩在饱和土中的扭转耦合振动问题,提出了桩与土在谐和振动情况下的定解问题，先对土层动力平衡方程进行求解并得到土体扭转振动位移形式解，依据平衡条件将该形式解耦合进桩身动力平衡方程，并通过对桩动力平衡方程的求解，得到桩顶转角和切向速度频域响应解析解和半正弦脉冲激励作用下桩顶时域响应的半解析解.数值分析结果表明，桩的长径比和波速比对桩顶动力响应有较大的影响，孔隙率和渗透力影响较小.将扭转振动结果与纵向振动分析结果进行了对比，二者在图形形状上有很多相似之处.

Study on torsional vibration of pile embedded in saturated soil

Biot's linear theory for porous,fluid-saturated media was used to theoretically investigate dynamic response of an end bearing pile embedded in a saturated soil layer.The equilibrium equations of a linear elastic isotropic soil undergoing axisymmetric torsional deformations in cylindrical coordinates were solved at first.Then,the vibration displacement solution with an undetermined constant of the soil layer was obtained.Coupling of the solution into a one-dimensional governing equation of a pile yielded an analytical solution.The harmonic complex stiffness and admittance at the pile top in frequency domain were defined.And the velocity response in time domain was obtained by using Fourier inverse transform.Numerical results were obtained for analyzing the influences of corresponding parameters on the response.It was observed that the influences of the slenderness ratio of a pile and wave velocity ratio were remarkable but that the influences of the porosity and seepage force were minor.Comparison of the numerical results of the longitudinal vibration with those of the torsional vibration showed that they have much in common in the shape of the figures.