@article{samu_guddati_2021, title={Field Validation of Effective Dispersion Analysis of Reflections, a New Method for Nondestructive Estimation of Pile Depth}, ISSN={["2169-4052"]}, DOI={10.1177/03611981211008186}, abstractNote={ Several methods have been developed for nondestructive pile depth estimation over the past few decades, with impact-based methods remaining popular because of their ease of application. Sonic-echo techniques rely on generating nondispersive longitudinal waves by impacting the pile top and subsequently picking peaks that correspond to initial and reflected wave arrivals. Unfortunately, pile tops are often inaccessible for in-service foundations and alternate impacting techniques result in signals for which time domain peak picking can be difficult. Pile sides are often easily accessible, but side impact generates highly dispersive flexural waves resulting in complicated waveforms for which analysis is not straightforward. Existing methods to process dispersive flexural waves rely on signal processing based methods and do not explicitly incorporate the physical dispersion properties of the system, resulting in large errors. To address the current limitations, a new method called effective dispersion analysis of reflections (EDAR) was recently developed for pile length estimation. EDAR provides a simple and robust technique to analyze dispersive flexural waves generated from side impact for which time domain processing is not applicable. In this paper, length estimation through EDAR is explained for longitudinal and flexural waves using synthetic bar and Timoshenko beam models. Field validation for two types of pile, concrete filled steel tubes and prestressed concrete, with varying cross sections and embedment are presented. EDAR resulted in pile length estimates within 10% error. }, journal={TRANSPORTATION RESEARCH RECORD}, author={Samu, Vivek and Guddati, Murthy}, year={2021}, month={Apr} }
 @article{samu_guddati_2020, title={Nondestructive length estimation of an embedded pile through combined analysis of transverse and longitudinal waves}, volume={110}, ISSN={["1879-1174"]}, DOI={10.1016/j.ndteint.2019.102203}, abstractNote={This paper presents an important modification of the recently developed nondestructive testing method for estimating embedded depth of pile foundations – EDAR – effective dispersion analysis of reflections. The original EDAR method is based on processing dispersive bending wave signals in the frequency-effective wavenumber domain, thus eliminating the need to perform time-domain peak picking that is difficult due to over-distortion of reflected signals. While EDAR was successful in laboratory settings, preliminary field validation resulted in significant errors. After careful examination of the wave physics, it is discovered that both longitudinal and transverse waves need to be carefully included in EDAR analysis. Specifically, it is shown that the initial arrival is dominated by transverse waves, while the reflections are dominated by longitudinal waves, owing to significant attenuation of transverse waves due to compacted soil around the pile. This observation led to a refined EDAR methodology and accurate estimation of embedded pile depth in field settings.}, journal={NDT & E INTERNATIONAL}, author={Samu, Vivek and Guddati, Murthy}, year={2020}, month={Mar} }
 @article{samu_guddati_2019, title={Nondestructive Method for Length Estimation of Pile Foundations Through Effective Dispersion Analysis of Reflections}, volume={38}, ISSN={["1573-4862"]}, DOI={10.1007/s10921-019-0583-8}, number={2}, journal={JOURNAL OF NONDESTRUCTIVE EVALUATION}, author={Samu, Vivek and Guddati, Murthy}, year={2019}, month={Jun} }