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| Research on 3D reconstruction method of rock fracture surface based on CGAL |
| PENG Shoujian1，WU Bin1，XU Jiang1，SHI Ruoran2，YAN Fazhi1，WU Shankang1 |
| (1. State Key Laboratory of Coal Mine Disaster Dynamics and Control，Chongqing University，Chongqing 400044，China；
2. Department of Computer Science，Columbia University，New York 10027，USA) |
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Abstract The geometric characteristics of the fracture after hydraulic fracturing determine the strength，deformation behavior and seepage characteristics of the fractured rock mass. In order to further quantitatively analyze the surface roughness，fracture aperture，occurrence and fractal characteristics of sandstone fracture surfaces under the coupling of shear stress and water injection pressure，a method for 3D reconstruction of fracture surface based on the computational geometry algorithms library(CGAL) was proposed. Combined with the grayscale distribution of CT images of fractured specimens，preprocessing method was optimized to ensure the accuracy of the 3D reconstruction. The Delaunay refinement algorithm was used to reconstruct surfaces of fractured specimens. Surface planes of specimens were detected employing random sampling consistent algorithm，which helped to realize automatic tilt correction and coordinate setting. Finally，the fracture surface could be extracted by cropping. It is quantitatively characterized by calculating the fracture communication volume，fracture communication area and fractal dimension. The results show that based on the 3D model of fractures，the development of fracture systems in sandstone specimens under the coupling of shear stress and water injection pressure can be reproduced，which provides a foundation for the geometric quantitative characterization of fracture surface and numerical simulation of fracture surface seepage behavior.
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2020, Vol. 39 
