ABSTRACT:

In this paper a new conception is presented to determine of the integrity of the pile by the reflection wave method and the classification of the integrity of the pile.

1.
THE QUALITY AND THE INTEGRITY OF THE PILE

Sometimes we confuse the pile quality with the pile integrity, but in fact they are different. The concept of quality commonly used internationally is defined as the sum total of characters which reflect tile capacity of the object to satisfy the explicit and the implicit needs. The explicit need of pile quality is divided into three kinds:

  1. homogeneity of the material of the pile;

  2. strength grade of the concrete;

axial compression and tension bearing capacity of the single pile, and the resistance to bend and shear. For implicit needs, there are two kinds:

  1. insufficience of support force of neihbhouring piles in the group pile bearer, and the support of the instability of neihbhouring piles;

  2. endurance and disaster resistance (for example the earthquake as a disaster) of the pile material. The explicit needs of tile integrity of the pile mainly are homogeneity of the pile; velocity of plastic longitudinal wave, defects of the pile (the position, the form and tile extent of the defects). The implicit need is to assess according to wave velocity concrete strength grade and the influence of defects of the pile on tile bearing capacity of the single pile.

2.
INTEGRITY OF THE PILE TESTED BY THE REFLECTION WAVE METHOD

In the integrity test technology, the reflection wave method is used very widely, besides to the embedment supersonic test. The test technique of the reflection wave method is comparatively mature, and the test results are repeatedly confirmed by the core boring method. At present the majority of testers take the theory of wave of the one dimensional bar as the only basis of tile method. However, the author is of the following opinion. The vibration is produced mainly by the hammering on the pile head, and the vibration signal first received by the vibration pickup installed on tile pile head is the vibration signal of the particle on the pile head. Therefore, vibration theory should be one of the theoretical bases. In analysis of the form and the extent of defects of the pile, Huang Lixing et al. have put forward a theory of wavelet effect i.e. a new conception: principal wave + wavelet = waveform measured. This theory has provided a new theoretical basis for quantitative judgement of the defect extent of the pile. For analysis of serious defects in the shallow part, especially the stratified defects, e. g. broken piles and fracture piles, the repeated reflection is the best theoretical basis. From what are mentioned above, we can come to the conclution that in the reflection wave test of the integrity. different theories should be taken as the bases for different problems. The reflection wave test is characterized by the transient vibration.

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