###### Abstract  
As civil engineering projects grow increasingly complex, ensuring pile integrity is essential for pile bearing capacity and structural safety. Pile integrity testing (PIT) has long been a focal point for researchers and engineers. With the rapid development of industrial-level advancements and artificial intelligence technology, PIT methods have undergone significant technological advancements. This paper reviews traditional PIT techniques, including low-strain integrity testing and thermal integrity profiling. The review covers the principles, advantages, limitations, and recent developments of various testing techniques. Additionally, recent advances in artificial intelligence (AI) techniques, particularly in signal processing and data-driven recognition methods, are discussed. Finally, the advantages, limitations, and potential future research directions of existing methods are summarized. This paper aims to offer a systematic reference for researchers and engineers in PIT, synthesizing technical details of traditional methods and their AI-enabled advancements. Furthermore, it explores potential directions for integrating AI with PIT, with a focus on key challenges such as noisy signal interpretation and regulatory barriers in applications. pile integrity testing; pile; pile defect; non-destructive testing; artificial intelligence 2020  
12 June 202527 July 202527 July 2025  
unlike above-ground structures. Structural defects in piles compromise both the bearing capacity and overall structural safety of foundations. Failure to detect defects promptly or meet testing standards may result in significant economic losses and pose direct threats to public safety. Consequently, the adoption of appropriate testing techniques is essential for conducting comprehensive and accurate quality assessments of pile foundations. Non-destructive testing (NDT) has emerged as a critical tool for pile integrity evaluation [10; 11; 12]. Conventional PIT methods comprise low-strain integrity testing, acoustic transmission methods, radiation-based \(\gamma\)-\(\gamma\) logging, and thermal integrity profiling (TIP) methods, among others. Table 1 provides a comparative overview of PIT methodologies. To standardize PIT methods, several countries have issued corresponding specifications such as ASTM D5882-16 [13] and JGJ 106-2014 [14]. These specifications establish a basic framework for equipment requirements, signal acquisition procedures, and data interpretation. Low-strain integrity testing, a non-destructive evaluation method based on stress wave propagation theory, is widely employed for pile length assessment and major defect detection. Low-strain integrity testing comprises two primary categories: surface reflection methods (including acoustic echo, impulse response, and shock echo techniques) and borehole methods (such as acoustic logging and parallel seismic testing) [15]. Surface reflection methods demonstrate significantly greater cost-effectiveness compared to borehole testing approaches [16]. TIP has emerged as a promising technological advancement. This technique enables early-stage detection of structural defects in cast-in-place piles through thermal monitoring during concrete curing. This addresses a key limitation of conventional methods, which require approximately one-month waiting periods post-construction and  
Figure 1: Typical defects for cast-in-situ concrete piles [7]. often provide incomplete parameter assessments [17; 18]. Notably, in addition to concrete piles, wooden piles remain prevalent in coastal, water conservancy, and historical structures owing to their sustainability and cost-effectiveness [19; 20].