![]() As a result, interpreting field-obtained signals is currently performed manually by experienced experts only. In particular, interpreting the signals for detecting pile defects to determine defect types and locations requires experienced personnel with good knowledge of wave propagation theory, soil mechanics, and piling construction techniques, in addition to a good understanding of LSPIT itself. ![]() That is because many factors affect the wave propagation and thus the reflection signals. While field testing is relatively simple and can be performed fairly quickly by qualified personnel, assessing the pile integrity by interpreting the test signals is still quite challenging and involving. These reflections are later analyzed based on one dimensional stress wave analysis.Īn entire LSPIT involves two parts: (1) field testing-signal acquisition and (2) signal interpretation-qualitatively and quantitatively assessing pile integrity by interpreting the signals (velocity reflectograms) collected from the field test. Theses reflections are measured with the acceleration transducer installed on pile top. A stress wave introduced by the blow of a hand-held hammer on the pile top propagates axially along the pile, and reflections are generated whenever the stress wave encounters impedance changes (discontinuities). LSPIT works by following one-dimensional wave propagation theory. The popularity of LSPIT comes from the fact that it is effective in detecting major discontinuities or defects, such as cavities, cracks, necking, bulging, and soil inclusions, and relatively simple to perform in the field. Among these different integrity testing methods, LSPIT, also called the sonic echo test, is probably the most popular one widely used in various parts of the world. Over the years, many nondestructive evaluation (NDE) methods have been developed for reliably assessing the integrity of piles, for example, low strain pile integrity testing (LSPIT), high strain pile integrity testing (HSPIT), cross-hole sonic logging (CSL), single hole sonic logging (SSL), and gamma-gamma density logging (GDL). The proposed methodology can potentially enhance LSPIT and make it even more efficient and effective in quality control of deep foundation construction.Īssessing the structural integrity of deep foundation elements such as drilled or driven piles has always been a critical quality control task in the construction industry. We demonstrate the methodology’s effectiveness using the LSPIT signals collected from a number of real-world pile construction sites. Specifically, the methodology can ease experts’ interpretation burden by screening all test piles quickly and identifying a small number of suspected piles for experts to perform manual, in-depth interpretation. The methodology, built on advanced signal processing and machine learning technologies, can be used to assist the experts in performing both qualitative and quantitative interpretation of LSPIT signals. Motivated by this need, in this paper, we develop a computer-aided reflectogram interpretation (CARI) methodology that can interpret a large number of LSPIT signals quickly and consistently. Techniques that can automate test signal interpretation, thus shortening the LSPIT’s turnaround time, are of great business value and are in great need. ![]() For foundation construction sites where the number of piles to be tested is large, it may take days before the expert can complete interpreting all of the piles and delivering the integrity assessment report. While performing LSPIT in the field is generally quite simple and quick, determining the integrity of the test piles by analyzing and interpreting the test signals (reflectograms) is still a manual process performed by experienced experts only. ![]() Low strain pile integrity testing (LSPIT), due to its simplicity and low cost, is one of the most popular NDE methods used in pile foundation construction. ![]()
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