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基桩检测中,为了进行基桩缺陷的定量分析,精确地描述速度波传播和衰减的过程是非常重要的。为了考虑桩土相互作用对速度波传播的影响,将桩侧土对桩的作用简化为粘滞阻尼器,建立了瞬态锤击作用下桩纵向振动的定解问题,进而依据定解问题的解析解分析速度波波幅比沿桩身的衰减过程。由于桩纵向振动的解析解是桩土相互作用阻尼系数、半正弦波的脉冲宽度、瞬态激振力幅值、桩弹性模量、桩密度、桩长以及桩身截面积等参数的函数,所以利用正交试验方法分析了不同参数对速度波沿桩身衰减过程的影响。分析结果表明,桩土相互作用阻尼系数是影响速度波衰减的显著因素,而其他因素对速度波衰减的影响不显著,进而依据这一结论建立了速度波波幅比随时间和阻尼系数衰减的关系式。
In the test of pile foundation, in order to quantitatively analyze the defect of pile foundation, it is very important to accurately describe the process of velocity wave propagation and attenuation. In order to consider the effect of pile-soil interaction on velocity wave propagation, the effect of pile-side soil on piles is simplified as a viscous damper, and the solution to the problem of longitudinal vibration of piles under transient hammering is established. Then, Analyze and analyze the decay process of wave velocity ratio along the pile body. The analytical solution of pile longitudinal vibration is a function of parameters such as damping coefficient of pile-soil interaction, pulse width of half sine wave, amplitude of transient exciting force, elastic modulus of pile, pile density, pile length and pile cross- Therefore, orthogonal test method is used to analyze the influence of different parameters on the attenuation process of speed wave along pile body. The analysis results show that the damping coefficient of pile-soil interaction is a significant factor affecting the attenuation of velocity wave, while other factors have no significant effect on the attenuation of velocity wave. Based on this conclusion, the relationship between velocity amplitude and attenuation of damping coefficient is established formula.