Research on the Enlargement of Stope Span Based on the Pre-stressed Expandable Pillar Support Technology

• Published in: Rock mechanics and rock engineering 2021-09, Vol.54 (9), p.4663-4675
• Main Authors: Li, Kunmeng, Li, Yuanhui, Wang, Zhechao, Xu, Shuai, Xiong, Zhipeng
• Format: Article
• Language: English
• Subjects: Civil Engineering; Deformation; Deformation effects; Earth and Environmental Science; Earth Sciences; Economic benefits; Enlargement; Geophysics/Geodesy; Mathematical models; Mining; Onsite; Original Paper; Production capacity; Roofs; Technology; Vertical orientation
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-021-02514-y

In order to improve the production capacity and efficiency of orebodies, the stope span enlargement with the overhand drift-and-fill mining method based on the pre-stressed expandable pillar support technology is developed by numerical simulation and on-site industrial test. The results demonstrate that compared with the natural pillar support, the vertical deformation of stope roof increases approximately 10 mm, and the stress release and plastic failure of stope roof slightly increase under the pre-stressed expandable pillar support. However, relative to no support, the expandable pillar support can effectively limit the vertical deformation (about 13 mm), stress release and plastic failure of stope roof. The farther the monitoring point is from the stope center or support position, the smaller the vertical deformation and stress release of stope roof will be. In general, the expandable pillar support technology can realize the “yielding support” to stope roof. With the stope span enlarging, the load on the bar-shaped natural pillar is immediately transferred to the adjacent expandable pillars, and the closer the distance is between the expandable pillar and the mining area or the stope center, the greater the bearing stress increment on the expandable pillar will be. The maximum bearing load on pre-stressed expandable pillars does not exceed 700 kN. Deriving from the industrial test, the support design of pre-stressed expandable pillars by the traditional pressure arch theory is conservative. The actual load on the support body is 1/6 times or less than the rock mass weight of stope roof within a semicircular area, and the load bearing area is equivalent to a parabolic shape with large opening. After the on-site industrial test is completed, the stope and expandable pillars are visually safe and stable. From the perspective of technical benefits, the stope span enlarges from 3 to 9 m, the ore production capacity increases from 30 t/day to 90 t/day, and the ore recovery rate improves by 30%. In terms of economic benefits, the profit of test stope is 77026 US$.