Integrated orthophoto-GPR-GOCAD modeling for shallow cavity detection: a case study in Qinglong County, China

Abstract

Three-dimensional (3D) geological modeling is an essential tool for assessing digital mine safety and detecting underground cavities. This study systematically reviews the capabilities, advantages, and limitations of mainstream 3D geological modeling software, integrating orthophoto imagery and ground-penetrating radar (GPR) data with the GOCAD platform to construct a three-dimensional model of shallow cavity-related anomalies in Qinglong Manchu Autonomous County, Hebei Province. The GPR survey included 20 reconnaissance profiles and eight detailed profiles in the priority exploration area. Two principal target zones were identified from the measured GPR data: Target Zone 1 near C0071 on Line C at an interpreted depth of approximately 5–25 m, and Target Zone 2 near D0090 on Line D at approximately 3–12 m depth. A laterally continuous reflective interface was also identified at approximately 10 m depth and interpreted as the boundary between Quaternary unconsolidated sediments and the underlying bedrock. Orthophoto imagery provides surface constraints, while GPR data provides subsurface structural information. Their integration in GOCAD provides a common three-dimensional spatial framework for relating surface features, measured GPR anomalies, and field-verification results, rather than a quantitatively demonstrated improvement in detection accuracy. Field investigation and excavation at Target Zone 2 revealed a dolomite-hosted cave-fissure space filled with calcareous clay, angular dolostone breccia, and mammalian fossils, supporting the geological interpretation of the GPR anomaly. The detailed inter-profile geometry remains dependent on survey-line distribution and interpolation.