Field validation of water‐pipe leakage detection through spatial and time‐lapse analysis of GPR wave velocity

Abstract

Detection of leakage in a buried water pipe is a crucial issue, as underground pipes become aged and these pipes are often used as pathways for aggressive chemical agents. Non‐destructive geophysical methods for identifying such underground leakages are of vital importance. Leakage detection in buried water pipes is sometimes carried out through specific acoustic methods. In this research, we have used ground‐penetrating radar as an alternative to such acoustic methods, because of the high sensitivity of electromagnetic waves to the presence of water in soil. This paper presents a methodology, illustrated by field‐scale ground‐penetrating radar experiments. Four water leakage points in a buried, ductile, iron, main‐water pipe were pre‐designed within a full‐scale (20 m long × 10 m wide) experimental set up. This facility was paved half by reinforced concrete and half by other pavement blocks. Four ground‐penetrating radar antennae with five nominal frequencies 200, 250, 400, 600 and 900 MHz were tested. Using a modified algorithm for common offset ground‐penetrating radar antennae, in this work, we measure the changes in electromagnetic wave velocity and wave reverberation, which sense upward and downward leakages, respectively. Leakages could be identified most clearly in the 600 MHz ground‐penetrating radar data. Our result suggests two potential applications in terms of detecting and defining the extent of multiple leakages in old water pipes, and testing and commissioning new pipes before and after pressurized tests.

A framework for GPR‐based water leakage detection by integrating hydromechanical modelling into electromagnetic modelling

“…In addition, a horizontal reflection was observed at the bottom zone of the radargrams after 3 h, which was associated with the fully saturated rack bottom. Similarly, lab experiments done by Cheung and Lai (2019) indicated comparable GPR radargram variations that were dominated by the water spread directions including the upward and downward leakage.…”

Analysis of GPR Data Characteristics of Drainage Pipe and Cavity Coexisting

“…In this study, numerical simulation experiment is carried out using gprMax and combined with field experiment to clarify the GPR reflection characteristics when the drainage pipe and the cavity coexist. The following two points are recognized: (1) The diffraction formed by the two upper endpoints of the cavity is superimposed on each other in the GPR profile with V-shaped characteristics; (2) The cavity sidewalls and drainage pipe are prone to form multiple waves, but cause little interference with data interpretation. Further studies can set up multiple models for numerical simulation experiments to clarify the response characteristics of the cavities triggered by drainage pipe leakage in GPR data under multiple conditions.…”

“…The identification and diagnosis of defects of drainage pipe is one of the important contents of urban safety operation. Pipeline closed circuit television (CCTV) is currently the most mature, effective and safe technical means for pipeline condition inspection at home and abroad [1,2]. However, CCTV inspection has a high pre-workload and requires cleaning of the pipe and lowering the water level inside the pipe.…”

Enhancing stratigraphic, structural and dissolution features in GPR images of carbonate karst through data processing

“…Velocity analysis is then too limited and often reduced to estimating the mean velocities based on hyperbola fitting (e.g. Lanzarone and Bigman ; Cheung and Lai ). For example, fitting some of the diffraction hyperbolas appearing in the rectangle E (Fig.…”