An innovative determination approach for the support strength of stope roof: a case study.

In this study, a novel method to determine the support strength for stope roof in room and expandable prop mining is developed. The process consists of three main steps: determining the stope roof characteristic curve, and then carrying out regional division of the stope roof characteristic curve, and finally determining the support strength of the stope roof. For the gold mine in Dandong, China, the Universal Distinct Element Code (UDEC) numerical simulation method is utilized, and parameters related to the numerical simulation are precisely determined to define the characteristic curve of the stopsse roof. The point where the roof characteristic curve transitions from elastic to plastic deformation represents a support force of 5.2 MPa. The rock mass failure index is reintroduced, and the stope roof characteristic curve is categorized based on the stope roof’s failure degree. Meanwhile, the required support strength for the stope roof is ascertained. The region with a stress release coefficient of 0.5 < β < 1.0 is identified as the elastic zone, whereas the region with 0.05 < β < 0.5 is defined as the plastic zone. The region with 0.02 < β < 0.05 is regarded as the fracture zone. Finally, the region with 0 < β ≤ 0.02 represents the potential damage zone. Meanwhile, the required stope roof support strength for the gold mine in Dandong, China, is determined to be 0.35 MPa. Based on the determined stope roof support strength, an on-site industrial test is carried out. Nine expandable props are designed, and their load-bearing performances, as well as stope stability, are monitored. After mining the stope, visual observations show that apart from minor cracks in the stope roof, both the roof and expandable props remain largely stable. This indicates that the calculation method for determining stope roof support strength is more practical and secure.