Mechanism and effect analysis of prestressed anchoring support mechanism of long-span crushed rock mass roof.

The roof of a large-span broken rock mass is supported by prestressed anchorage, which can maintain the stability of the roadway roof to the greatest extent. Therefore, it is of great significance to study the supporting mechanism and supporting effect of prestressed anchorage on the roof of large-span broken rock mass for ensuring the long-term stability of large-span underground engineering and open-pit large-section tunnel engineering under broken rock mass. The strength change of anchorage body after anchorage is analyzed and the pre-stressed anchorage support mechanism of the roof of large-span broken rock mass is analyzed. Taking the support problem of large-span roadway in grade IV broken rock mass of Jinchanghe Polymetallic Mine as the engineering background, a numerical model is established for its support mode. The layout of structural unit Cable in FLAC^3D software, the key part of numerical model establishment's analyzed. A new three-stage layout method is designed. The bolt and anchor cable are divided into pre-tightening section, free section, and anchorage section at FLAC^3D software level, and their specified parameters are given for numerical calculation. Three groups of numerical simulation schemes with different support methods are established to prove the effect of prestressed anchorage support. The results show that the tensile stress of the roof in the support area is less than the tensile strength of the broken rock mass roof. Compared with the ordinary non-prestressed support design scheme, the plastic zone volume decreases by 61. 95%, and the vertical settlement of the roof in the Z direction decreases by 83. 90 %. The surrounding rock in the prestressed anchorage range is effectively controlled, and the safety of the stope roof is guaranteed. [ABSTRACT FROM AUTHOR]