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| DOI：10.13522/j.cnki.ggps.2026027 |
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| Identification of subsurface defects in irrigation canal linings using 3D ground-penetrating radar |
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Zhu Jie, Guo Wei, Zou Yuanyuan, Lu Liguo, Li Taiyun, Shi Suqi
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Identification of subsurface defects in irrigation canal linings using 3D ground-penetrating radar
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| Abstract: |
| 【Objective】In seasonally frozen regions, canal lining cracking is an important factor responsible for structural deterioration and reduced water-conveyance efficiency. Since subsurface damage may be more extensive than indicated by surface observations, accurate diagnosis of the distribution and extent of subsurface defects requires efficient and nondestructive imaging techniques. This paper investigated the capability of three-dimensional ground- penetrating radar (3D GPR) for detecting subsurface defects in a concrete-lined canal in Ningxia, China.【Method】Full-coverage, high-density GPR data were collected from a cracked section in the canal. In combination with A-scan and B-scan spectral analysis, core-drilling observations and geotechnical tests, the structural layering, spatial morphology of cracks and associated subsurface defects were quantitatively interpreted and validated.【Result】①GPR profiles identified the complete structural stratification, which consisted of a 30-40 cm concrete lining and a 30 cm backfill-soil layer; the interface reflections were consistent with the design specifications. ②The canal lining showed a composite defect pattern, comprising cracks, loosened zones and voids. The maximum crack depth was 25 cm. The cracks did not penetrate the entire lining layer but extended in a dendritic pattern. Local debonding and poorly compacted soil zones were identified at the bottom of the cracks and along the concrete–backfill-soil interface. ③Soil testing and mechanical analysis indicated that a localized weak layer with a compression modulus as low as 4.32 MPa occurred at a depth of 40-60 cm in the middle portion of the canal slope. Under seasonal freeze-thaw cycles, the maximum tensile stress in the lining slab ranged from 1.85 to 3.22 MPa, exceeding the specified tensile strength of C25 concrete (1.78 MPa). This provided a mechanism underlying the initiation and propagation of cracks. ④The features and spatial distribution of defects detected by GPR were consistent with the mechanical response of the canal lining under seasonal frost-heave and thaw-settlement cycles observed in the region.【Conclusion】Our findings demonstrate the potential of 3D GPR for identifying and three-dimensionally characterizing subsurface defects in concrete canal linings. Multidimensional data-fusion analysis indicated that heterogeneous soil compaction, seasonal freeze-thaw cycles and the self-weight of the concrete lining slab jointly contributed to lining cracking. |
| Key words: irrigation district lined canal 3D ground penetrating radar hidden defect quantitative identification radar spectral characteristics |
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