Research on combined support technology of three fork roadway in soft and hard interbedded rock mass

Abstract

In order to solve the problem of complex stress and instability in the intersection area of roadway under the condition of soft and hard interbed roof, taking 1113 three-fork roadway of Qiuji Coal Mine as the engineering background, the stress distribution law at the intersection is studied by theoretical analysis method, and the deformation and failure mechanism of surrounding rock is revealed; based on the strength strengthening theory of surrounding rock, thick anchor plate theory, integrated support theory and suspension theory, a combined support system of “anchor （cable）+anchor cable beam+steel mesh” is formed, and various key support parameters are calculated. The research results show that the acute angle triangle area of three-fork belongs to a high stress concentration area, and the surrounding rock of the roadway is easy to be damaged. The maximum damage depth is 2.77 m according to the theoretical calculation; under the control of combined support system, through numerical simulation verification, the maximum concentrated stress in the triangle area is 10.74 MPa, the maximum roof subsidence is 16.82 mm, and the maximum damage depth is 2.24 m, which can effectively improve the mechanical state of surrounding rock; after the site implementation, there is no obvious separation of the roof, meeting the safety needs.

Keywords

• inter-bedded rock mass
• three fork roadway
• joint support
• numerical simulation
• field test