单缺陷桩反射波法动测曲线峰-峰点反演的精度研究

STUDY OF PEAK-PEAK PRECISION INVERSION FOR REFLECTED WAVE TESTING CURVES OF SINGLE DEFECT PILES

从理论计算、物理解释和实际资料验证3个方面,研究了由反射波法动测曲线峰-峰点反演桩身缺陷位置的精度问题。结果表明,当桩身波速准确时,峰-峰点反演精度主要由缺陷实际长度与定义的缺陷临界长度的比值决定。若该比值大于或等于1,缺陷反演位置与缺陷实际位置接近;若该比值小于1,缺陷上界面反演深度较浅,下界面反演深度较深。对这种短缺陷的缺陷反演长度变大现象,通过该缺陷上界面反射的上行拉力波与下界面反射的上行压力波的叠加来解释,并由实测资料予以证实。

Based on theoretical calculation,physical interpretation and practical testing data,the precision of inversion of shaft defect locations by peak-peak reflected wave testing curves for single piles is studied. The results indicate that the precision mainly depends on the ratio of the defect length to the critical defect length defined in this paper when the wave velocity in the piles is accurate. If the ratio is more than or equal to 1,the inversion defect locations are close to the true ones. If the ratio is less than 1,the inversion depth of the upper defect surface is shallower,while that of the lower defect surface is deeper. The inversion defect length for piles with short defect becomes larger than real one because of the superimposition of upward tensile wave reflected by the upper surface and upward compressive wave reflected by the lower surface,and this is verified by practical testing data.