Abstract
Abstract Low strain integrity tests in piles are relatively cheap, of quick execution and nondestructive. Despite all these advantages, several variables are involved and the influence of external factors can complicate the interpretation of the results. Between them, the influence of the pile reinforcement can be high lighted. In piles partially reinforced, the difference in density and elastic modulus of the concrete in different parts of the pile and the influence of the process of introducing the reinforcement bars can induce some reflections in the test that can be confused with damage in the pile and, therefore, should be taken into account to analyze the tests results. In this research, the influence of the reinforcement embedded in the piles is analyzed using numerical (FEM) simulations and comparing them with tests made in the field. A new classification of possible damages is proposed based on the analysis of the reflections observed at the end of the reinforcement cage embedded in a pile partially reinforced.
Highlights
The risks associated with integrity problems in deep foundations led Brazilian and international standards to include the theme in their texts
In one-dimensional simulations of low strain integrity tests, the load is considered applied at the top of the pile and the effects resulting from the location of the impact at the top of the pile are not taken into account, nor the effects resulting from the relation between the contact area of the hammer and the area of the top of the pile neither the effects arising from the radiation of the waves near the top of the pile
It is possible to demonstrate that, with this, the analysis by the Beta method, that is based on the relation between amplitudes of the peaks observed in the reflectogram, proposed by Rausche and Goble [25], with graphical data collection, was impaired, especially when the transition from the reinforced to the unreinforced part of the pile is located at relevant depths at the pile, when the steel/concrete rate is high and when the damping effects generated by the soil are high.In the cases studied, the Beta values calculated graphically directly from the reflectograms indicated in Figures 1 to 5 are 0.45% to 18.60% greater than the Beta values obtained analytically
Summary
The risks associated with integrity problems in deep foundations led Brazilian and international standards to include the theme in their texts. Not required by the Brazilian standard, some companies have demanded from their suppliers the execution of low strain integrity tests in up to 100% of the piles [1]. Interpretation of the results of these tests is often difficult especially when there are changes in the cross section of the piles or when there is influence of the surrounding soil [2]. One option to evaluate the results obtained in low strain integrity tests and the influence of these factors on the results is to simulate the test numerically or analytically and compare the theoretical result obtained with the result obtained in the field. Finite elements numerical models developed by the author are used to evaluate the influence of the embedded reinforcement on partially reinforced piles in the low strain integrity test results. A new classification system of possible damages in the transition between reinforced and unreinforced parts of the piles is proposed different from those currently used as published by Liang and Rausche [13], Webster, Rausche and Webster [14] and Cunha, Camapum de Carvalho and Silva [15]
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