高承台桩基无偏心竖向激励低应变测试方法研究

Research on low-strain test method of high-cap pile foundation without eccentric vertical excitation

为了弥补传统低应变检测方法在识别带高承台的桩基完整性及桩长信息等方面的缺陷,提出了一种新型无偏心竖向激励方式以及一种桩身轴向多点速度响应行波分解法。进一步地,通过二维及三维有限元模型验证了该方法在识别带高承台的桩基完整性及桩长信息等方面的可行性。最后,对所提出的方法开展了如桩身尺寸、承台尺寸、传感器设置等一系列影响因素的参数分析研究。结果表明,通过本方法对原始的复杂速度响应进行数据处理后可以得到一桩底反射区清晰可辨的响应曲线,消除了上部结构复杂振动特性及环境高频噪声的影响,从而有效地预测了未知的桩长。该研究解决了现有无损检测方法局限性,对实际工程中带高承台桩基的完整性判断及桩长预测有一定的参考意义。

In order to make up for the shortcomings of traditional low-strain detection methods in identifying the integrity of high-cap pile foundation and the pile length information,a novel vertical uneccentric excitation method and an axial multi-point traveling wave decomposition of a series of velocity responses along the shaft pile are proposed in this study.Furthermore,two-dimensional and three-dimensional finite element models are used in this study to verify the feasibility of the method in identifying the integrity of high-cap pile foundation and pile length information.Finally,a series of influencing factors such as pile size,capsize,sensor setting locations,spacing,and other parameters are analyzed.The research results show that this method can eliminate the influence of the superstructure complex vibration characteristics and high-frequency noise after processing the initial complex speed response.Hence,a clear and identifiable response curve of the bottom reflection of the pile and effectively predicting the unknown pile length can be obtained.It can be concluded that this study can break through the limitations of the existing non-destructive testing methods and has reference significance for the integrity judgment of the existing high-cap pile foundation and the pile length prediction in actual engineering.