横向惯性效应对基桩动测的影响分析

Analysis on the Influence of Lateral Inertia to Dynamic Test for Pile Foundation

在桩的振动理论中,对大直径桩,不能把桩简单看成一维杆件,必须考虑其横向尺寸产生的横向惯性效应。通过横向惯性效应的运动方程进行拉氏变换,推导出桩顶在正弦激振力作用下的位移和速度的响应传递函数以及速度导纳表达式,并分析了横线惯性效应对基桩动测时域曲线的影响以及其影响因素。在不考虑材料阻尼、桩周土条件下,发现横向惯性效应会降低应力波速度,并产生衰减作用,同时脉冲宽度和桩径大小直接影响着横向惯性效应的强弱。

In the theory of pile vibration, one-dimensional assumption is not suitable for the large diameter pile, The influence of lateral inertial effect must be taken into account. This paper presents the solution of the motion equation of lateral inertial effect with Laplace transforms and develops the velocity response function under semi - sine wave exciting force at the level of pile tip. The paper also presents the analysis on the influence of lateral inertial effect of the dynamic response curves in the time - domain and its factors. Taking no account of the influence of pile material damping and the surrounding soil, it is found that both the velocity decreasing and attenuation of the stress wave are due to the lateral inertial effect. Meanwhile, different pulses and diameters also have an important influence on the lateral inertial effect.