The failure of buried pipelines can lead to serious consequences such as explosions, environmental pollution, settlement, as well as economic loss. To prevent these outcomes, it is crucial to identify the causes of failure and monitor their signs. One of the main causes of failure is unexpected third-party interference (TPI), which is particularly challenging to detect. Regarding to this issue, this study proposes a new algorithm for monitoring impact damage, which can be used for prompt response and damage prevention. The algorithm is integrated into the system using two approaches. The first approach focuses on detecting the location of the damage (referred to as source location). A kurtosis-based transfer function was newly proposed to selecting the optimal frequency band for time-difference-of-arrival based source location, resulting in accurate pinpointing of damage, even in a noisy environment. The second approach is used to determine whether impact damage has actually occurred by observing newly suggested features in both the time and frequency domains (referred to as anomaly detection). These features evaluate the presence of damage and the similarity between signals. As a result, it was evaluated that the field applicability was higher than that of conventional methods, and the superiority of the proposed method was also verified through field experiments. The method proposed in this study is expected to enable immediate response when the integrity of the buried pipelines is on the line of failure due to TPI.

Big impacts from pressure transients are known to be major contributors to pipeline failures, and even small impacts have the potential to result in pipeline deterioration. The effects of these impacts on a pipeline are not disclosed in detail and are hard to evaluate completely by theoretical modeling or numerical simulation. The impacts excite cylindrical structures containing liquid, which results in the development of wave propagation along pipelines. In particular, quasi-longitudinal waves are known to be developed by fluid-structure interaction during propagation. However, impact signal detection needs great care because extreme noise may corrupt the signal. An enhanced wavelet-based approach is proposed to detect and localize the impact source. The method makes use of continuous wavelet transform and band summation within a band of interest along scales to enhance time-difference detectability. In addition, a noise reduction algorithm intended to remove burst noises, in practice, frequently contaminates the impact signals of interest. Experimental results from a water supply network under operation demonstrate that the proposed approach is able to suppress noise and successfully reveal the impact location. The proposed approach provides a more precise and robust way to localize impacts missed by the conventional cross-correlation algorithm.

Buried pipelines, such as waterworks pipelines, are critical for transmitting essential resources and energy in modern cities, but the risk of pipeline failure, especially due to third-party interference, is a major concern. While various studies have focused on leak detection in waterworks pipelines, research on preventing impact damage is limited. To address this issue, this study proposes a novel algorithm that utilizes energy and similarity measurements for impact detection and compares it theoretically to existing leak-detection methods. The proposed algorithm utilizes frequency-domain kurtosis to determine the frequency band on which the energy of the impact signals is concentrated, along with a time-shift coherence function to measure the similarity of the signals. The application of the source location using the filtered signals enables accurate detection of the location of third-party interference. The proposed algorithm aims to ensure the safety and to prevent failures of buried pipelines. To verify the feasibility of the proposed algorithm, an excavation experiment using a backhoe was conducted on an in-service waterworks pipeline with a diameter of 2200 mm and a burial depth of 3 m. This experiment confirmed the effectiveness of the proposed algorithm in preventing failures of buried pipelines and demonstrated its practical applicability in the field. The experiment also validated the algorithm’s ability to detect third-party interference damage at various points.

대구경 용수공급 배관에서 발생하는 충격 손상은 파손으로 연결되어 누수를 유발할 수 있다. 특히, 매설된 배관에서의 누수는 경제적 손실과 함께 땅 꺼짐 현상으로 인한 안전문제를 야기할 수 있다. 이러한 배관의 안전한 관리를 위해 이상 징후가 나타난 위치를 아는 것은 사고의 예방과 조기 대응을 위해 중요하다. 진동 신호를 이용한 배관의 상태감시는 오랫동안 많은 연구가 진행되어 왔으며, 특히 관내 유체와 연성되어 전파하는 파동은 장거리 전파가 가능하여 이상지점을 탐지하는데 효과적인 것으로 주목받고 있다. 정확한 이상지점 탐지를 위해서는 배관을 따라 전파하는 파동의 전파속도를 정확하게 아는 것이 필수적이다. 본 연구에서는 실제로 운용 중인 대구경 용수 배관에서 유체 연성 파동의 전파속도를 추정하고자 한다. 대상 배관의 관경은 1,200 mm 이며, 길이 136 m 구간의 실제 배관에서 진동 가속도계를 설치하여 충격신호를 측정하였다. 배관의 주파수응답 분석을 통하여 충격으로 발생된 유체 연성 파동의 속도 추정에 적합한 최적의 주파수 대역을 선정하였다. 이를 통해 실험적으로 전파 속도를 구하였으며, 이론적으로 구한 전파속도의 결과와 잘 일치함을 확인하였다.