Stability assessment of surrounding rock in downward mining route supported by slab-wall backfill structure.

Characteristic of ground pressure in surrounding rock is generally considered as the theoretical basis of parameter optimization for stope structure and technology. To explore the feasibility of efficient method for the second-step downward route backfill stopes in Shanjin gold mine, various numerical simulation methods were used to investigate the effect of slab-wall backfill structure on stability of surrounding rock in downward route mining system. The maximum principal stress, artificial false roof stress, and displacement were analyzed to evaluate the level of ground pressure in different mining areas. These results indicate the optimized structural parameters for backfill stopes, which may also provide a low-cost way to achieve a high safety for downward route mining system.

A method of blasted rock image segmentation based on improved watershed algorithm.

It is of great theoretical significance and practical value to establish a fast and accurate detection method for particle size of rock fragmentation. This study introduces the Phansalkar binarization method, proposes the watershed seed point marking method based on the solidity of rock block contour, and forms an adaptive watershed segmentation algorithm for blasted rock piles images based on rock block shape, which is to better solve the problem of incorrect segmentation caused by adhesion, stacking and blurred edges in blasted rock images. The algorithm first obtains the binary image after image pre-processing and performs distance transformation; then by selecting the appropriate gray threshold, the adherent part of the distance transformation image, i.e., the adherent rock blocks in the blasted rock image, is segmented and the seed points are marked based on the solidity of the contour calculated by contour detection; finally, the watershed algorithm is used to segment. The area cumulative distribution curve of the segmentation result is highly consistent with the manual segmentation, and the segmentation accuracy was above 95.65% for both limestone and granite for rock blocks with area over 100 cm2, indicating that the algorithm can accurately perform seed point marking and watershed segmentation for blasted rock image, and effectively reduce the possibility of incorrect segmentation. The method provides a new idea for particle segmentation in other fields, which has good application and promotion value.