Quantitative Analysis of Low-strain Characteristics on Defective Piles with Constriction or Segregation

As one of the most commonly used dynamic pile test technologies, low-strain reflected wave method is increasingly used in pile integrity testing. Currently, field test is only operated in the simple discriminant of defect, but is lack of the comprehension of stress reflection law of different degree defects, especially of the quantitative analysis of defect. To solve the problem, differences between reflected wave of different defective piles are compared, situations with different segregation degrees are simulated with finite element method. The degree of pile concrete segregation was quantificational analyzed in accordance with the theory that velocity-time curve is consistent, which combines the defect characteristics of the ratio between reflected wave peak and incident wave peak ,and the concrete modulus between segregation section and the normal. The construction of finite element method will be significant guidance for practical engineering.