Abstract
To address the problems of low work efficiency, high safety risk, and survey blind spots in the investigation of high-steep dangerous rock masses, this study takes the No. 1 high-elevation dangerous rock mass at a hydropower project as an example and establishes an investigation system for such rock masses using technologies including close-range photogrammetry and ground-penetrating radar. Technical methods are employed to construct a three-dimensional oblique photogrammetry model of the dangerous rock mass, accurately determining its boundary conditions and engineering geological characteristics. Based on the obtained data, the instability mechanism and failure mode of the dangerous rock mass are analyzed, and stability evaluation is performed. The results indicate that the No. 1 dangerous rock mass has a thickness of approximately 14.1 m, a length of about 27.1 m, a maximum concave rock cavity depth of 4.6 m, and a volume of 2210 m³, classifying it as a large-scale dangerous rock mass. The development depth of rear tensile fractures ranges from 7.6–9.0 m, and the failure mode is of the falling type. Under natural, seismic, and rainstorm conditions, the stability coefficients of the dangerous rock mass are 1.16, 1.08, and 1.04, respectively, corresponding to stable, basically stable, and marginally stable states. The non-contact measurement technology of oblique photogrammetry and the tensile fracture detection technology of ground-penetrating radar compensate for the limitations of single technologies in information acquisition, solving the problems of low efficiency, high safety risk, and survey blind spots associated with traditional investigation methods. This provides new ideas and methods for the identification and detection of high-steep dangerous rock masses and offers reference value for the investigation and evaluation of similar high-steep dangerous rock masses.
Full Text
Construction of Three-dimensional Model and Stability Analysis of Unstable Rock Mass Based on Nap-of-the-object Photogrammetry and Ground Penetrating Radar Technology
OU Anfeng¹, WU Shuyu¹, YANG Jinjun¹, YU Jiasong¹, HOU Shuai²
¹Power China Guiyang Engineering Corporation Limited, Guiyang 550081, China
²Power China Electric Power Investment Group Co., Ltd., Lanzhou 730030, China
Abstract
To address the challenges of low efficiency, high safety risks, and survey blind spots inherent in traditional investigations of high and steep unstable rock masses, this study develops a comprehensive investigation system integrating nap-of-the-object photogrammetry and ground penetrating radar (GPR) technologies. Using the No. 1 high-level unstable rock mass at a hydropower project as a case study, we constructed a three-dimensional oblique photogrammetry model to accurately delineate the rock mass boundaries and characterize its engineering geological features. Based on the acquired data, we analyzed the failure mechanism and mode, and performed a stability assessment.
The results indicate that the No. 1 unstable rock mass has a thickness of approximately 14.1 m, a length of about 27.1 m, a maximum cavity depth of 4.6 m, and a total volume of 2210 m³, classifying it as a large-scale unstable rock mass. The tensile fractures at the rear edge developed to depths of 7.6–9.0 m, and the failure mode is determined to be of the falling type. Under natural, seismic, and rainstorm conditions, the stability coefficients of the rock mass are 1.16, 1.08, and 1.04, respectively, corresponding to stable, basically stable, and less stable states.
The integration of non-contact oblique photogrammetry and GPR for tensile fracture detection overcomes the limitations of single-technology approaches in information acquisition, resolving the problems of low efficiency, high safety risks, and survey blind spots associated with conventional investigation methods. This provides new ideas and methods for the identification and detection of high and steep unstable rock masses and offers valuable reference for similar investigation and evaluation efforts.
Keywords: nap-of-the-object photogrammetry; ground penetrating radar; unstable rock mass; fracture development depth; stability