缺陷桩的旁孔透射波法检测分析原理

Analysis of Defects of Pile Shaft for Parallel Seismic Test

以均质弹性地基中具有低速缺陷段的基桩为研究对象,利用基于Snell定律的射线理论,对旁孔中首至透射P波的时深关系推导了一套简化理论计算公式,并由此提出了采用旁孔透射波法检测分析桩身缺陷的方法.对饱和地基中具有低速缺陷段的基桩,采用轴对称有限元法模拟计算了旁孔透射波法测试信号,对其按上述方法分析推算桩身低速缺陷段的位置、长度和波速以及桩长,以检验本文方法的可靠性.结果表明,本文方法具有良好的实用潜力,值得开展进一步的验证和试用工作.

Based on Snell＇s law for simplified pile-soil models, a series of formulae of time-versus-depth relations of the first-arrival of P wave in the parallel seismic test （PST） were derived and a reasonable method for determination of pile defects was proposed in this paper. An axisymmetric finite element model of a single defected pile in saturated soil was used to simulate the PST. The location, length and P-wave veloci- ty of the defect in the pile shaft as well as the pile length were analyzed with the method presented. The results proved the application potential of the method proposed this paper, which is worth of further verifi- cation by field tests.