Early strength characteristics and applicability analysis of plain shotcrete support of a mine

Aiming at the problem that the plain shotcrete support of a mine is easy to crack and fall off under the condition of mining disturbance, the uniaxial compressive strength test of the existing support is carried out, the strength characteristics of the existing support and its relationship with the amount of accelerator and water consumption are analyzed. On this basis, through on-site stress monitoring, the characteristics of radial secondary compressive stress of roadway roof and side are studied, and the applicability of plain shotcrete support is analyzed. The results show that the radial secondary compressive stress of roadway roof induced by stope mining is greater than that of roadway side. The uniaxial compressive strength of the existing plain shotcrete support is less than the radial secondary compressive stress of the roadway, which is the main reason for the failure of the existing plain shotcrete support. The strength of the existing plain shotcrete support increases first and then decreases with the increase of water consumption, and decreases with the increase of the amount of accelerator. Compared with the support without accelerator, the strength loss of the existing support is about 73.6%. Reducing the amount of accelerator to 40% of the current amount or increasing the water consumption to 1.30 times the current amount, the uniaxial compressive strength of the plain shotcrete support will be greater than the radial secondary compressive stress of the roadway, which is conducive to improving the ability of the plain shotcrete support to resist the secondary stress induced by the mining of the stope.