【作者】 李鹏明； 高前进； 李浩； 郝晓辉； 毕华军；

【Author】 LI Pengming;GAO Qianjin;LI Hao;HAO Xiaohui;BI Huajun;Water Resources Research Institute of Shandong Province;

【机构】 山东省水利科学研究院；

【摘要】 为了分析瞬态激励下基桩的动力响应及应力波的传播特性,通过理论分析和有限元数值模拟相结合的方法研究了应力波在理想状态下沿基桩传播的特性和在自由端、固定端、阻抗变化处的性状,结果表明有限元分析结果与理论分析的结果一致,可见采用的三维桩基础有限元模型具有一定的可靠性;然后基于现场实测的桩顶力信号,反向运用到有限元分析软件中进行实际模拟,并与现场实测曲线进行对比,同时对试验实测信号进行了时域和频域分析,试验结果表明两种分析方法对桩长的判定上误差均在5%范围内,因此两种方法在估算桩长和缺陷位置时,可相互辅助验证;最后本文采用时频域和小波分解的方法对典型曲线进行了分析,对锤击过程中的能量分布及频域成分进行直观的展示,试验分析结果表明锤击信号主要集中在低频范围以内且能量在低频段集中,因此检测过程中若出现背景噪音和环境振动等偶然因素导致的高频成分,可设置低通滤波器对低频和高频进行分离,并对测试信号进行聚焦处理来降低外界因素对信号的影响。更多还原

【Abstract】 This article aims to analyze the dynamic response of foundation pile under transient excitation and the propagation characteristics of stress waves. A combination of theoretical analysis and finite element numerical simulation is used to investigate the characteristics of stress wave propagation along the foundation pile in ideal conditions and at free, fixed, and impedance varying terminals. The results show that the finite element analysis results are consistent with the theoretical analysis results, indicating that the 3D pile foundation finite element model used in this article has a certain reliability. Subsequently, based on the field measured pile top force signal, the method is reversed and applied to the finite element analysis software for actual simulation, and coMPared with the field measured curve. At the same time,time domain and frequency domain analyses are conducted on the test measured signal. The test results show that the error of the two analysis methods in estimating pile length and defect location is within 5%, indicating that these two methods can complement and validate each other when estimating pile length and defect location. Finally, this article use time-frequency domain and wavelet decomposition methods to analyze typical curves, visually demonstrating the energy distribution and frequency domain components during the hammering process. The test analysis results show that the hammering signal is mainly concentrated in the low frequency range and energy is concentrated in the low frequency band. Therefore, in the detection process, if high frequency components caused by background noise and environmental vibration or other accidental factors are detected, low-pass filter can be used to separate low frequency and high frequency, and focused processing can be performed on the test signal to reduce the influence of external factors on the signal.更多还原