Abstract: The failure to characterize subtle difference would occur when the existing available methods were used to identify the structural domain boundaries of rock masses at underground mine. Here, research on the three-dimensional refined demarcation of homogeneous structural domains of jointed rock masses at underground mine was carried out, and geological survey data of the No. 3 block of the Zn polymetallic orebody in Tongkeng Mine (China) was used to demonstrate the validity of the method. In view of the spatial structure of jointed rock masses, a three-dimensional structural network model of the jointed rock mass at the underground mine was built based on the coupling of deterministic-stochastic discontinuities, and the model was subsequently discretized with orthogonal meshes. The values of the blockiness levels of the meshes were adopted to determine the homogeneous structural domain boundaries. The K-means clustering algorithm was used to test the similarities of data sources (i.e., meshes), and the sum of squared error (SSE) was employed to measure the quality of clustering. Finally, the rock mass structural domains were reconstructed from the perspective of three dimensions, and the method to three-dimensionally demarcate the homogeneous structural domains of rock masses was consequently formulated. The result shows that the method could accurately divide the structural domains of rock masses in three dimensions and provide a beneficial reference to the subsequent research works (e.g., rock mass quality evaluation and DEM simulation).

Key words: underground mine, rock mass homogeneous structural domains, three-dimensional demarcation, blockiness index