The analysis of the influence of defect length of foundation Piles to the precision of quantitative analysis in low strain non-destructive testing

摘要

In the low strain integrity testing of foundation piles by reflected wave metho 1 d, engineering and technical personnel usually carry out quantitative analysis of defects to piles on the basis of ratio of the defect reflected wave amplitude to incident wave amplitude, the defect reflected wave amplitude affects significantly the quantization of defects to piles.When the defect length of the pile is small, due to oppositional superimposition of reflected wave of the upper and lower defect interface, defect reflected wave amplitude becomes smaller, which make quantitative analysis have great error. To the quantitative analysis of low strain non-destructive testing of foundation pile, it is a significant issue how defect length affects defect reflected wave amplitude.In this paper, based on full-scale model test of piles and physical interpretation,the influence of defect length to defect reflected wave amplitude is studied,and some valuable results is obtained, which is important to quantitative analysis of low strain non-destructive testing of foundation piles. The results indicate:if the defect length of piles is less than the critical defect length defined in this paper, the reflected wave amplitude becomes smaller; if the defect length is longer than or equal to the critical defect length, the defect length does not have the influence to the defect reflected wave amplitude.