基于正交试验方法的速度波衰减规律研究

Study on Attenuation Rule of Velocity Wave Based on Orthogonal Experimental Method

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 order to analyze pile defects quantitatively,it is very important to describe the propagation and attenuation process of velocity wave accurately in pile detection.To consider the influence of pile-soil interaction to the propagation of velocity wave,the action of the soil beside the pile to the pile is simplified to a viscous damper.The pile longitudinal vibration problem of fixed solution under transient impact is established.With the analytic solution of the problem,the attenuation process of velocity wave amplitude ratio along the pile is analyzed.Due to the analytic solution of pile longitudinal vibration is a function of the damping coefficient,the impulse duration and the amplitude of transient impact force,and the elastic modulus,density,length,sectional area of pile,the orthogonal experimental method is used to analyze the effect of different parameters to the process of velocity wave attenuation along the pile.The results show that the only significant factor which influences the attenuation of velocity wave is damping coefficient,and the other factors are insignificant parameters.With the conclusion,the relational expression of the attenuation of velocity wave amplitude ratio,which is a function of time and damping coefficient,is established.