均匀黏弹性地基中X形桩纵向振动响应简化解析方法

Simplified analytical solution for vertical vibration of X-section pile in homogeneous viscoelastic soil

现浇X形混凝土桩(简称X形桩)是一种新型异形截面桩。考虑X形桩异形截面凹弧段和凸弧段的动摩阻力分布和桩-土耦合振动,假设桩周土为均匀黏弹性体,运用Laplace变换和坐标变换法推导得到X形桩纵向振动响应简化解析方法。将所得解退化到实心圆桩的解,验证了简化解件解的合理性。分析了桩长、开弧间距、开弧角度等对桩顶复刚度和速度导纳的影响,得到桩体尺寸参数对X形桩纵向振动特性影响的规律。分析表明:在有效桩长范围内桩长越长,刚度和阻尼越大,速度导纳曲线的震荡幅值和共振频率越小;在低频段X形桩顶速度导纳受开弧间距和开弧角度的影响较小,在高频段速度导纳随开弧间距的增大而减小,随开弧角度的增大而显著增大,速度导纳曲线的震荡幅值随开弧间距的增大而增大,随开弧角度的增大而减小。

X-section cast-in-place concrete pile(X-section pile) is a kind of new special-shaped pile. Considering the distribution of dynamic friction resistance on concave arc section, convex arc section and soil-pile coupled vibration, treating the soil as axisymmetric homogeneous viscoelastic medium, the analytical solution in frequency domain is obtained by using Laplace transformation technique and coordinate transformation. The solution is compared with that of solid circular pile to verify the rationality. Moreover, by analyzing the effect of pile length, open arc spacing and open arc angle on complex dynamic stiffness and velocity admittance, the influence of dimension parameters on the vertical vibration characteristics of X-section pile is investigated. It shows that the complex dynamic stiffness at the top of pile increases, the oscillation amplitudes and resonant frequencies of the velocity admittance curves significantly decrease with the increase of pile length. The open arc spacing and open arc angle have little influence on the velocity admittance at low frequencies. At high frequencies, the velocity admittance decreases with the increase of open arc spacing and increases with the increase of open arc angle. However, oscillation amplitudes of the velocity admittance curves increase with the increase of open arc spacing and decrease with the increase of open arc angle.