基于解析解的混凝土桩体应力波特性分析

Analysis of stress wave characteristics of concrete pile based on analytic equation

把混凝土桩体简化为一维粘弹性体,应用牛顿定律构造本构方程,在不同边界条件和初始条件下,利用分离变量法求出对应的响应波动方程.在此基础上,研究了混凝土桩体不同截面处应力波幅值的衰减规律.结果表明:桩体中应力波在时间和空间上呈指数衰减,衰减程度与衰减系数有关;不同边界条件下,应力波的位移幅值和速度的衰减以及瞬态波形都有很大差异;受土体阻尼和桩体内部粘滞力的影响,截面距桩顶越远位移幅值发生衰减越快,且每个截面达到最大幅值的时间点越滞后;波动图像出现不同程度的跃起,主要是对波动方程的依赖性造成的.

In this study, the concrete pile was simplified to one-dimensional viscoelastic body; Newton＇s law was applied to construct the constitutive equation; and the method of separation of variables was used to solve the corresponding response wave equation under different boundary conditions and initial conditions. On this basis, the concrete pile was studied in different interface stress amplitude attenuation. The results indicate that the pile stress wave decays exponentially in time and space, and the attenuation degree is related to attenuation coefficient. There are great differences for the displacement amplitude of stress wave and velocity attenuation as well as transient waveform under different boundary conditions. With the influence of damping of soil and pile body internal viscous force, the farther the interface away from the top of the pile, the faster the interface displacement amplitude attenuation, and the later the maximum amplitude of arrival. Moreover, different leaping degrees of wave images are mainly due to the dependence on wave equation.