Stability analysis of rock blocks around a cross-harbor tunnel using the improved morphological visualization method

• Separating axes algorithm was employed to improve the efficiency of EBAA.
• Weighted quick-union method was applied to improve the efficiency of CBCA.
• Improved morphological visualization method was incorporated into the BLKLAB code.
• The application of the modified BLKLAB code was demonstrated through a case study.

The morphological visualization method is improved by introducing the separating axes method to the element-block aggregation algorithm and the weighted quick-union method to the complex-block construction algorithm to enhance the computational efficiency of BLKLAB (Zhang and Lei, 2013a). The usage and effectiveness of the modified BLKLAB code are demonstrated through a case study of Xiang'an tunnel in Xiamen City of China. In this case study, the DifFUZZY method was employed to cluster the orientation data and probabilistic analysis was then performed to get a combination of geological and mechanical properties of discontinuities that is most detrimental to the stability of rock blocks and associated ground-supports. Based on these previous analyses, the fracture network was constructed. The stability of rock blocks around the tunnel was then evaluated, using the improved morphological visualization method in conjunction with the stereo-analytical method. A combination of shot concrete and bolts was proposed as the optimal support system, which agrees with the real situation.